Chapter 1: Systems, Quantities, and Units MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A plot of the ratio of the output of a circuit to the input is called a A) gain transfer B) block diagram C) transfer curve D) conductance ratio 2) The electrical symbol for voltage is A) R B) C
1)
_.
2) C) V
3) Express 7.5 × 10-4 in milli, basic units, and micro. A) 75 milli, 0.0075, 750 micro C) 75 milli, 0.075, 7500 micro
D) I 3)
B) 7.5 milli, 0.075, 75000 micro D) 0.75 milli, 0.00075, 750 micro
4) The difference between electrical and electronic systems is A) one is analog and the other is digital B) the voltage levels C) there is no major difference other than terminology D) electrical deals with power while electronic deals with signals
4)
5) Determine the correct calculation. A) 5.6 ÷ 17 m = 32.9 m C) 5600 × (9.6 × 10-7) = 5.376 milli
5) B) 89.4 k × 1.2 m = 1.072 km D) 4.7 m ÷ 1.24 = .379 m
6) The combining of skills from mechanical and electronic disciplines is called A) mechatronics B) integrated learning C) horizontal integration D) vertical integration
6)
7) A model of a complex electronic system is often simplified and represented as a A) timning diagram B) flow chart C) block diagram D) logic ladder
7)
8) If your calculator displays 3.45607 × 106, the equivalent metric value with 4 significant digits is . A) 3.456 micro B) 34.56 Mega C) 3.456 Mega D) 3.456 kilo
8)
9) The metric value 16 mA can be expressed as A) 16 × 10-3 A B) 16 × 10-6 A
9)
10) The value 1.2 × 10-6 can be expressed as A) 1.2 M or Meg B) 1.2 m or milli 11) The symbol for electrical charge is A) C B) I
. C) 16 × 100 A
D) 16 × 103 A
C) 0.00012
D) 1.2 µ or micro
C) V
D) Q
.
10)
.
11)
1
12) Multiply 3 mA by 1000 × 10-6 and express the result in microamperes. A) 300 µA B) 3 µA C) 30 µA
D) 3000 µA
13) Convert 0.00047 microfarads (µF) to the equivalent picofarads (pF). A) 0.47 pF B) 4.7 pF C) 470 pF
D) 47 pF
14) Express 5.6 × 10-2 in milli, basic units, and micro. A) 5600 milli, 56, 560 C) 560 milli, 5.600, 5600 micro
12)
13)
14) B) 5.6 milli, 0.056, 56000 micro D) 56 milli, 0.056, 56000 micro
15) Express these two calculator displays in correct metric units: 5.6 - 07 2.2 05 A) 0.56 micro, 220 kilo B) 56 micro, 220 kilo C) 56 micro, 22 kilo D) 0.56 micro, 0.022 Meg 16) 500 mA is equal to A) 0.5 Amps
15)
.
16) B) 0.0005 kA
C) 500,000 µA
D) all of the above
17) The correct metric expression for 8.54 × 10-5 is _ A) 854 pico B) 85.4 micro
. C) 85.4 milli
D) 85.4 kilo
18) Signals that vary continuously are called A) oscillators B) digital signals
C) analog signals
D) active circuits
17)
18)
19) If you are trying to enter the number 16,000 into your calculator, a correct entry is . A) 1.6 04 B) 1.6 05 C) 1.6 02 D) 1.6 03
19)
20) Add 21 mA and 8000 µA and express the result in milliamperes. A) 21.8 mA B) 290 mA C) 218 mA
20) D) 29 mA
21) Pico is what relation to micro? A) 1/10th B) 1/100th
D) 1/1,000,000th
21) C) 1/1,000th
22) The metric prefix µ (micro) is normally associated with measurements. A) large B) extremely small C) small D) extremely large
22)
23) 0.6 kV is equal to A) 6 V
23)
_. B) 600 V
C) 0.6 V
24) To enter 0.00000056 into your calculator, use the entry . A) 5.6 -08 B) 00056 -05 C) 56 -06 25) If your calculator displays 3.5 - 06, the equivalent metric value is . A) 35 milli B) 3.5 pico C) 35 micro D) 3.5 micro 26) 86,000 expressed in scientific notation equals A) 860 × 102 B) 8.6 × 10-4
D) 60 V
D) 56 -08
25) E) 3.5 Meg
_. C) 8.6 × 103
2
24)
26) D) 8.6 × 104
27) Any component that requires a source of power to function is called A) a load B) a source C) an amplifier D) an active component
27)
28) The difference between scientific and engineering notation is A) groupings of multiple of three digits B) single vs multiple digits before decimal point C) powers of ten representation D) all of these
28)
29) Mega is what relation to kilo? A) 10 times B) 100 times 30) The electrical symbol for inductance is _ A) I B) C
.
29) C) 1000 times
D) 1,000,000 times
C) V
D) L
.
30)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 31) 0.0047 amps can be expressed in engineering notation as 47 µA.
31)
32) Vertical organization is more specialized than horizontal organization
32)
33) 0.00015 can be expressed in powers of ten as 1.5 × 10-4.
33)
34) The first step in designing a circuit is to build it using design software.
34)
35) AC is often converted to DC with a power supply
35)
36) In engineering notation, 82,500 is expressed as 8.25 × 103.
36)
37) A boundary defines the dividing line between a system and everything else.
37)
38) The symbol µ is an abbreviation for 10-6 or micro.
38)
39) Scientific notation is the most widely used form of technical notation in electronics.
39)
40) Engineering notation is typically used in the expression of extremely large and small quantities in the electronics field.
40)
41) In engineering notation 0.0047 is expressed as 4.7 × 10-3.
3
41)
Answer Key Testname: CH 1
1) C 2) C 3) D 4) D 5) C 6) A 7) C 8) C 9) A 10) D 11) D 12) B 13) C 14) D 15) A 16) D 17) B 18) C 19) A 20) D 21) D 22) B 23) B 24) D 25) D 26) D 27) D 28) D 29) C 30) D 31) FALSE 32) FALSE 33) TRUE 34) TRUE 35) TRUE 36) FALSE 37) TRUE 38) TRUE 39) FALSE 40) TRUE 41) TRUE
4
Chapter 2: Voltage, Current, and Resistance MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Figure 2- 1 1) Identify the DPST switch in Figure 2-1. A) graph (a) B) graph (b)
1) C) graph (c)
D) graph (d)
E) graph (e)
2)
Figure 2- 2 2) In Figure 2-2, if you place a voltmeter's red lead on point E and its black lead on point H, you will be measuring . A) VR5 B) VR6 C) VR4 D) VR7
1
Figure 2- 1 3) Which switch in Figure 2-1 is usually used to control a doorbell? A) graph (a) B) graph (b) C) graph (c) D) graph (d) 4) A resistor with yellow, violet, orange and silver bands equals . A) 4.7 k▲ ± 10% B) 47 k▲ ± 10% C) 47 M▲ ± 10%
3) E) graph (e)
D) 47 k▲ ± 5%
4)
5) In the American Wire Gauge sizes, as the numerical value of AWG goes higher, the cross sectional area of the wire: A) halves. B) decreases. C) increases. D) doubles.
5)
6) On a resistor with numbers and letters, the position of the letter in the sequence represents: A) the tolerance. B) the numerical total. C) the decimal point. D) the resistance value.
6)
Figure 2- 1 7) Which switch in Figure 2-1 could be used to open a circuit momentarily? A) graph (a) B) graph (b) C) graph (c) D) graph (d)
7) E) graph (e)
8) On a resistor with five bands of color code, the fifth band may represent that: A) the tolerance in percentage of value. B) the resistor is a precision resistor. C) the reliability in percentage of failure. D) all of these.
8)
9) An analog meter has . A) a digital readout C) a needle and a scale to indicate the value
9) B) no moving parts D) a high degree of accuracy
2
10) If a resistor equals 1.2 ▲ ±5%, its color code is _ A) brown, red, gold, gold C) brown, red, silver, gold
. B) brown, black, red, gold D) brown, black, gold, silver
10)
Figure 2- 1 11) Identify the Normally Closed Push Button switch in Figure 2-1. A) graph (a) B) graph (b) C) graph (c)
11) D) graph (d)
E) graph (e)
12) Electrolysis A) is a chemical reaction B) can produce a high-resistance connection C) can result from splicing two wires of different materials D) all of the above 13) Which unit of charge contains 6.25 × 1018 electrons? A) a coulomb B) an ampere
12)
13) C) a volt
14) In order to measure the current in a circuit, an ammeter must A) be placed so the current must pass through the meter B) be placed across the load C) be placed across the source D) all of these
D) a joule .
14)
Figure 2- 1 15) Identify the Rotary switch in Figure 2-1. A) graph (a) B) graph (b)
15) C) graph (c)
3
D) graph (d)
E) graph (e)
16) The voltage measured directly across an open switch in a circuit will be: A) half of applied voltage. B) 0 V. C) full applied voltage. D) unpredictable.
16)
Figure 2- 3 17) What does the schematic symbol (b) represent in Figure 2-3? A) rheostat B) potentiometer C) photoconductive cell D) thermistor
17)
18) Every electrical circuit must contain A) a battery, a resistor and a capacitor C) a source, a load and a path
18)
_. B) a battery, a path and a switch D) a source, a load and a resistor
19) A(n) is a material that has many free electrons. A) insulator B) poor conductor C) conductor
19) D) semiconductor
20) Which of the following is not a type of variable resistor? A) potentiometer B) thermistor C) photoconductive cell D) All are types of variable resistors.
4
20)
Figure 2- 1 21) The Rotary switch in Figure 2-1 is most likely to be used as _ A) an old manual TV channel selector. B) a range selector switch in an analog voltmeter. C) a selector for different voltages in a power supply. D) all of the above
.
21)
22) Voltage is . A) the opposition to the flow of current B) the force that exists between charged particles C) the force that causes water to flow D) the movement of free electrons
22)
Figure 2- 2 23) In Figure 2-2, a voltmeter placed across points C and D will measure A) VR3 B) VR1 C) VR4 24) In Figure 2-2, the voltage VCE is the same as _ A) VR5 B) VR6
_. C) VR3 + VR4
25) A source, a path, and a load _ . A) do not make up a complete circuit B) will allow current to flow if the switch is open C) can only be an open circuit D) make up a basic circuit
5
.
23) D) VR2 24) D) VR4 + VR5 25)
26) Interpret the following mixed numbers and letters 4R7 on a resistor to the correct resistance of: A) 4.7 Kilohms. B) 4.7 Megohms. C) 4.7 ohms. D) 47 ohms.
26)
Figure 2- 1 27) Which switch in Figure 2-1 would probably be used to control a light and a fan at the same time? A) graph (a) B) graph (b) C) graph (c) D) graph (d) E) graph (e)
27)
28) Interpret the following mixed numbers and letters 3M3 on a resistor to the correct resistance of: A) 3.3 Kilohms. B) 330 Kilohms. C) 33 Kilohms. D) 3300 Kilohms.
28)
29) Most DMMs will measure A) voltage, current, capacitance C) frequency, voltage, current
29)
and
. B) voltage, current, resistance D) voltage, frequency, resistance
30) A common type of resistors are: A) carbon-composition. C) metal film. 31) An insulator is a material with A) some free electrons C) all free electrons
30) B) wirewound. D) carbon film. .
31) B) very few free electrons D) very many free electrons
32) A downside of using deep-cycle batteries is A) they are inefficient C) they are expensive
32) B) they require regular maintenance D) all of the above
33) A resistor with yellow, violet, orange, and gold bands equals . A) 47 M▲ ± 10% B) 4.7 k▲ ± 10% C) 47 k▲ ± 10%
6
D) 47 k▲ ± 5%
33)
Figure 2- 2 34) To measure the current that flows through R6 in Figure 2-2, the circuit must be opened and the ammeter placed at point . A) H B) F C) G D) E
34)
35) What do you call a diagram that shows the electrical connections of a circuit's components? A) an electrical diagram B) a pictorial diagram C) a schematic diagram D) a block diagram
35)
Figure 2- 2 36) In Figure 2-2, the voltage VFG is the same as _ A) VR9 B) VR8
_. C) VR7
D) VR6
37) In Figure 2-2, the voltage VGH is the same as _ A) VR7 B) VR9
_. C) VR5
D) VR6
7
36)
37)
Figure 2- 1 38) Which switch in Figure 2-1 could be used to simultaneously open or simultaneously close two circuits? A) graph (a) B) graph (b) C) graph (c) D) graph (d) E) graph (e)
38)
39) An ohmmeter should . A) be placed across the resistor after the resistor has been disconnected from the circuit B) be inserted into the circuit so the current flows through it C) have the polarity carefully checked before its use D) be connected across a circuit with the power on
39)
Figure 2- 1 40) Identify the Normally Open Push Button switch in Figure 2-1. A) graph (a) B) graph (b) C) graph (c)
40) D) graph (d)
E) graph (e)
41) Potentiometers and rheostats differ in that: A) potentiometers utilize three terminals, while rheostats usually use only two terminals. B) potentiometers utilize linear and nonlinear tapers, while rheostats usually utilize only linear tapers. C) potentiometers are used to vary voltages, while rheostats vary currents. D) all of these.
41)
42) The opposition to the flow of current is called A) current B) voltage
42)
. C) resistance
8
D) capacitance
43)
43) If a resistor is color coded with orange, orange, orange and silver bands, the resistance equals , the lower tolerance limit equals and the upper tolerance limit equals A) 33 k▲, 26,400 ▲, 39,600 ▲ B) 33 k▲, 31,350 ▲, 34,650 ▲ C) 33 k▲, 29,700 ▲, 36,300 ▲ D) 33 k▲, 32,670 ▲, 33,330 ▲ 44) If a resistor is color coded with red, red, orange and silver bands, the resistance equals the lower tolerance limit equals , and the upper tolerance limit equals _ A) 22 k▲, 19.8 k▲, 24.2 k▲ B) 22 k▲, 21.5 k▲, 22.4 k▲ C) 22 k▲, 17.6 k▲, 26.4 k▲ D) 22 k▲, 20.9 k▲, 23.1 k▲
.
,
44)
.
45) On a resistor with four bands of color code, the fourth band represents: A) the tolerance percentage. B) the multiplier value. C) the voltage rating. D) the wattage rating.
45)
46) Which type of resistor is used for high power applications? A) film B) surface mount C) wire wound D) carbon composition
46)
47) A 100 k▲ ±10% resistor is color coded _ A) brown, black, yellow, gold C) black, brown, yellow, silver
47)
. B) brown, black, yellow, silver D) brown, green, black, gold
Figure 2- 1 48) Which switch in Figure 2-1 could be used to switch two inputs to different output positions? A) graph (a) B) graph (b) C) graph (c) D) graph (d) E) graph (e)
48)
49) If the measured circuit current is zero, it is likely that the . A) circuit voltage is very high B) voltage is turned off C) circuit has a short D) resistance is very low
49)
50) The basic difference between a fuse and a circuit breaker is that: A) a circuit breaker is more reliable. B) a circuit breaker is reusable. C) a fuse is reusable. D) a fuse is faster.
50)
9
Figure 2- 1 51) Identify the DPDT switch in Figure 2-1. A) graph (a) B) graph (b)
51) C) graph (c)
52) To measure a circuit's source voltage, the voltmeter must A) have the black lead towards the positive side of the source B) have the red lead towards the negative side of the source C) be placed across the source D) be placed in series in the circuit
D) graph (d)
E) graph (e)
.
52)
53) A resistor with orange, orange, red and gold bands has a value and tolerance of . 53) A) 33 k▲ ±5% B) 3.3 k▲ ±10% C) 3.3 k▲ ±5% D) 33 k▲ ±10% 54) If the current in a circuit equals 0 A, it is likely that the _ . A) circuit has a short B) voltage is too high C) resistance is too low D) circuit is open
54)
55) A conductor is a material that has . A) few free electrons C) a structure similar to semiconductors
55) B) a positive charge D) many free electrons
56) What is the key difference when taking voltage measurements with an analog meter versus a digital meter? A) adjustment of the scale B) where the negative lead is placed C) proper choice of the scale on the display D) safety procedure in taking the measurement
56)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 57) To measure the current through a resistor, place the ammeter so the current must pass through the meter.
57)
58) The movement of free electrons through a conductor is called current.
58)
59) Resistance is the opposition to the flow of current.
59)
60) A Normally Open Push Button switch can carry current when not pushed.
60)
10
61) A resistor color-coded with brown, black and orange bands has a value of 10,000 ▲.
61)
62) For electrical current to flow in a circuit, voltage must be applied to that circuit.
62)
63) The Nickel-Metal Hydride battery is an example of a secondary battery.
63)
64) Electrons have a positive charge.
64)
65) Electrons attract each other.
65)
66) The ohm is the basic unit of resistance.
66)
67) Electromotive force is measured in volts.
67)
68) An element with a relatively large amount of electrons in the valence ring is considered to be a good conductor.
68)
69) A SPST switch is used to control one circuit.
69)
70) A generator converts electrical energy into mechanical energy.
70)
71) A resistor color coded with yellow, violet and orange bands has a value of 4.7 k▲.
71)
11
Answer Key Testname: CH 2
1) A 2) D 3) C 4) B 5) B 6) C 7) D 8) A 9) C 10) A 11) D 12) D 13) A 14) A 15) E 16) C 17) A 18) C 19) C 20) D 21) D 22) B 23) A 24) C 25) D 26) C 27) A 28) D 29) B 30) A 31) B 32) D 33) D 34) B 35) C 36) D 37) B 38) A 39) A 40) C 41) D 42) C 43) C 44) A 45) A 46) C 47) B 48) B 49) B 50) B 12
Answer Key Testname: CH 2
51) B 52) C 53) C 54) D 55) D 56) C 57) TRUE 58) TRUE 59) TRUE 60) FALSE 61) TRUE 62) TRUE 63) TRUE 64) FALSE 65) FALSE 66) TRUE 67) TRUE 68) FALSE 69) TRUE 70) FALSE 71) FALSE
13
Chapter 3: Ohm's Law, Energy, and Power MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) If a resistor that is color-coded red-red-brown-silver is connected to a 15 V source, what is the maximum current that can flow? A) 62 mA B) 71.9 mA C) 75.8 mA D) 68.2 mA
1)
2) Which of the following terms is not a resistor rating? A) power rating B) resistor value in ohms C) current D) resistor tolerance
2)
Figure 3- 1 3) If voltage is 12 V and the resistance is color-coded brown-black-orange in Figure 3-1, what are the minimum and maximum possible currents? A) IMINIMUM = 0.8 mA, IMAXIMUM = 1.2 mA
3)
B) IMINIMUM = 1 mA, IMAXIMUM = 1.6 mA C) IMINIMUM = 1 mA, IMAXIMUM = 1.5 mA D) IMINIMUM = 1.2 mA, IMAXIMUM = 1.4 mA 4) According to Ohm's Law, if voltage were to decrease while resistance remained the same, current would A) increase B) remain the same C) decrease D) no way to determine
4)
5) The voltage of a power supply drops to 0 V when connected to a lamp circuit. What is a possible problem? A) the lamp is open B) the lamp requires more current than the power supply can deliver C) the lamp is shorted D) both B and C
5)
6) A 220 ▲ 1/2 W resistor has burned open, so you look in your parts box to find a replacement. Which one of the following resistors could you use to repair the circuit? A) 220 ▲ 1/8 W B) 2200 ▲ 1/2 W C) 220 ▲ 1/4 W D) 220 ▲ 1 W
6)
7) In the operation of electrical circuits, which, in most cases, is an unwanted by-product? A) mechanical motion B) heat C) light D) both B and C
7)
1
Figure 3- 1 8) If V = 12 V and a 12 k▲ resistor shorts in Figure 3-1, the current is A) 10 mA B) 1 mA C) 0 A 9) If the resistor opens in Figure 3-1, the A) resistance decreases C) circuit current drops to 0 A
.
8) D) extremely high
.
9) B) power dissipation increases D) source voltage decreases to 0 V
10) If a resistor is rated at 1/2 W, it . A) always dissipates 1/2 W B) always provides 1/2 W of power C) can only dissipate more than 1/2 W of power D) can safely dissipate 1/2 W of power
10)
Figure 3- 1 11) If the resistor opens in Figure 3-1, the following circuit conditions would exist. A) resistor would read infinite resistance B) no power dissipation C) no current flow D) all of the above
11)
12) Typically, which is the first type of measurement taken in a known defective circuit? A) power B) current C) resistance D) voltage
12)
13) Using Watt's law and substituting power can be calculated as A) P = VI B) P = I2R C) P = V2/R
13)
2
. D) all of these
Figure 3- 1 14) If V = 50 V and R = 25 k▲ in Figure 3-1, the current equals A) 0.5 mA B) 2 mA C) 50 mA
_.
14) D) 5 mA
15) The ampere-hour rating of a battery is defined as the: A) number of amperes supplied over the number of hours at a given current. B) number of hours per amperes supplied. C) number of amperes supplied in 1 hour. D) all of these.
15)
Figure 3- 1 16) If I = 32 mA and R = 469 ▲ in Figure 3-1, the voltage equals _ A) 22 V B) 15 V C) 19 V
_.
16) D) 12 V
17) If the current flow for a given circuit has doubled, then the has been halved. A) power B) current C) resistance D) voltage
17)
18) If a resistor that is color-coded yellow-violet-brown-gold is connected to a 12 V source, then what is the current flow? A) 25.5 mA B) 26.9 mA C) 255 mA D) 24.3 mA
18)
19) The symbol for a certain amount of energy used over time is A) P B) W C) V
19)
. D) I
20) If a resistor that is color coded yellow-violet-red is placed across a 25 V source voltage, what value resistor and wattage rating could be used? A) 47000 ▲, 1/4 W B) 470 ▲, 1/2 W C) 4700 ▲, 1/8 W D) 4700 ▲, 1/4 W
3
20)
Figure 3- 1 21) If V = 100 V and I = 1 mA in Figure 3-1, the power dissipated by the resistor equals . A) 100 mW B) 1 W C) 10 W D) 10 mW
21)
22) According to Ohm's Law, if resistance were to decrease while voltage remained the same, current would A) increase B) remain the same C) decrease D) no way to determine
22)
23) If a resistance of 2.2 M▲ is connected across a 1 kV source, current equals about _. A) 2.2 mA B) 0.455 mA C) 0.455 A D) 45.5 µA
23)
24) If the voltage across a circuit increases, A) the current increases C) the resistance increases
24)
. B) the resistance decreases D) the current decreases
25) What is the resistance of a 100 W bulb when it is operating in a circuit with a supply of 120 V? A) 144 ▲ B) 56 ▲ C) 2.14 ▲ D) 560 ▲
25)
Figure 3- 1 26) If V = 25 V and R = 50 k▲ in Figure 3-1, the current equals A) 50 mA B) 5 mA C) 2 mA
_.
27) If I = 27 mA and R = 4.7 ▲ in Figure 3-1, the voltage equals _ A) 174 mV B) 127 mV C) 5.74 V
_.
28) Resistance and current are A) not related C) inversely proportional
26) D) 0.5 mA 27) D) 7.8 V
_.
28) B) directly proportional D) similar to voltage
29) A 250 µA current flowing through a 4.7 k▲ resistor produces a _ A) 53.2 V B) 1.18 V C) 18.8 V
4
voltage drop. D) 1.18 mV
29)
30) Braking resistors are A) used exclusively in the automotive field C) extremely high-tolerance components
30) B) very high-power resistors D) designed to fail as an open circuit
Figure 3- 1 31) If the voltage were suddenly switched on in Figure 3-1, A) the current would gradually decrease B) the current would flow C) the current would be zero D) the current would gradually decrease and then increase
.
31)
32) If a 1/2 W resistor is used in the circuit in Figure 3-1, the current value A) depends upon the circuit's voltage and resistance B) depends upon the voltage applied C) is over 12 mA D) is less than 12 mA 33) If I = 64 mA and R = 47 ▲ in Figure 3-1, the voltage equals _ A) 73.4 V B) 30.1 V C) 7.34 V 34) If V = 85 V and I = 15 mA in Figure 3-1, the resistance equals A) 567 ▲ B) 5.67 k▲ C) 1.28 ▲ 35) Which is the correct formula for Ohm's Law? A) V = I ÷ R B) P = V × I
.
32)
_.
33) D) 3.01 V .
34) D) 52.3 ▲ 35)
C) I = V ÷ R
D) R = V × I
Figure 3- 1 36) If the voltage is suddenly switched off in Figure 3-1, A) the current will suddenly drop to 0 A B) the current will first increase and then decrease to 0 A C) the current will gradually decrease to 0 A D) there is no way to predict the current
5
.
36)
37) If I = 45 mA and R = 40 k▲ in Figure 3-1, the voltage equals _ A) 1800 V B) 1.125 V C) 18 V
_.
37) D) 1.8 V
38) According to Ohm's Law, if voltage were to increase while resistance remained the same, current would A) decrease B) remain the same C) increase D) no way to determine
38)
Figure 3- 1 39) If V = 60 V and R = 47 k▲ in Figure 3-1, the current equals _. A) 12.8 mA B) 0.128 mA C) 128 mA
D) 1.28 mA
40) If V=12V and a 12k▲ resistor were to open in Figure 3-1, the current is A) 1 mA B) 0 A C) 10 mA
. D) extremely high
41) If V = 50 V and I = 37 mA in Figure 3-1, A) 135 m W B) 1.85 W
D) 1.35 W
42) Voltage and current are _ A) unrelated C) inversely proportional
is dissipated by the resistor. C) 0.185 m W
39)
40)
41)
.
42) B) quantities that add D) directly proportional
43) Current-sensing resistors are used in A) motor controllers C) computers
43) B) battery chargers D) all of the above
44) What is the resistance of a 150 W bulb when it is operating in a circuit with a supply of 125 V? A) 104 ▲ B) 75 ▲ C) 2.14 ▲ D) 9375 ▲
44)
45) Which is the most unlikely resistor failure? A) resistance change C) opening
45) B) shorting D) All are common failures.
46) Power as it is used in electric circuits can be best defined as: A) the rate energy is used over time. B) the rate current flows over time. C) the rate voltage is applied over time. D) the rate motion is exerted over time.
46)
47) If a resistor that is color-coded yellow-violet-orange-gold is placed across a 15 V source, the resistance and wattage rating could be . A) 0.47 M ▲ 1/4 W B) 47 k▲ 1/4 W C) 4700 ▲ 1/4 W D) 4.7 k▲ 1/8 W
47)
6
Figure 3- 1 48) If V = 72 V and I = 12 mA in Figure 3-1, the resistance equals A) 864 ▲ B) 47 k▲ C) 0.166 ▲
.
48) D) 6 k▲
49) The power rating of a resistor that must dissipate up to 1.1 W should be A) 5 W B) 1 W C) 2 W
. D) 0.25 W
49)
50) If a 10 k▲ resistor dissipates 0.5 W in Figure 3-1, then the supply voltage equals _. A) 50 V B) 7.07 mV C) 70.7 V D) 5000 V
50)
51) If I = 64 mA and R = 470 ▲ in Figure 3-1, the voltage equals _ A) 3.01 V B) 73.4 V C) 30.1 V
51)
Figure 3- 1
52) Which is the correct formula for finding power? A) P = V2 ÷ R B) P = I2 × R
_. D) 7.34 V
52) C) P = V × I
D) all of these
Figure 3- 1 53) If the voltage is 15 V and resistance is color coded red-red-brown-silver in Figure 3-1, what are the maximum and minimum possible current? A) IMINIMUM = 62.0 mA, IMAXIMUM = 75.8 mA B) IMINIMUM = 56.8 mA, IMAXIMUM = 85.2 mA C) IMINIMUM = 64.9 mA, IMAXIMUM = 71.8 mA D) none of these
7
53)
54) If a 330 ▲ resistor dissipates 2 W, its voltage drop equals A) 25.7 V B) 660 V C) 2.57 V 55) A kilowatt-hour is best defined as: A) a kilo divided by 1 watt-hour. C) 1,000 watts divided by 1 hour.
.
54) D) 6.6 V 55)
B) 1,000 watts multiplied by 1 hour. D) a kilo multiplied by 1 watt-hour.
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 56) When taking current measurements, it is extremely important not to accidentally place the meter across the voltage source.
56)
57) If the voltage applied to a circuit doubles, then power dissipation doubles.
57)
58) If a circuit's resistance increases, its current decreases.
58)
59) If a circuit's supply voltage is 15 V and its resistance is 4700 ▲, its current is 3.19 mA.
59)
60) If a circuit's resistance decreases, its current also decreases.
60)
61) If a 2.5 k▲ resistor carries 45 mA, it is dissipating 5.0625 W.
61)
62) Power rating for a resistor is mainly based on the physical size.
62)
63) If a 47 k▲ resistor carries 5 mA, it's safe to use a 1 W resistor.
63)
64) If a circuit's supply voltage is 20 V and its resistance is 3300 ▲, its current is 6.06 mA.
64)
65) If a 56 k▲ resistor carries 10 mA, it is safe to use a 10 W resistor.
65)
66) If a 12 k▲ resistor carries 12 mA, the resistor drops 1 V.
66)
67) An electronic power supply with a rated current capacity of 500 mA can adequately illuminate a 10 V @ 5 W lamp.
67)
68) If a 1 k▲ resistor has 32 mA flowing through it, it dissipates 1.024 W.
68)
69) If the current is constant, voltage and resistance are directly proportional.
69)
8
Answer Key Testname: CH 3
1) C 2) C 3) C 4) C 5) D 6) D 7) B 8) D 9) C 10) D 11) D 12) D 13) D 14) B 15) A 16) B 17) C 18) A 19) B 20) D 21) A 22) A 23) B 24) A 25) A 26) D 27) B 28) C 29) B 30) B 31) B 32) A 33) D 34) B 35) C 36) A 37) A 38) C 39) D 40) B 41) B 42) D 43) D 44) A 45) B 46) A 47) B 48) D 49) C 50) C 9
Answer Key Testname: CH 3
51) C 52) D 53) A 54) A 55) B 56) TRUE 57) FALSE 58) TRUE 59) TRUE 60) FALSE 61) TRUE 62) TRUE 63) FALSE 64) TRUE 65) TRUE 66) FALSE 67) TRUE 68) TRUE 69) TRUE
10
Chapter 4: Series Circuits MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Two 100 k▲ resistors are wired in series across a 20 V source. How much voltage does each resistor drop? A) 20 V B) 10 V C) 100 k▲ D) 100 mA
1)
2) What is the total supply voltage if 16 V and 12 V sources are wired in series opposing? A) 16 V B) 28 V C) 12 V D) 4 V
2)
3) A short in a series circuit results in: A) decreased power consumption. C) increased or maximum current flow.
3) B) increased circuit resistance. D) decreased or reduced current flow.
4) Four resistors are connected in series across an 18 V source. Three resistors drop 0 V and one resistor drops 18 V. What's the trouble? A) The three resistors are open. B) Two of the resistors are shorted. C) One resistor is open. D) There is no trouble; these voltages are normal.
4)
5) Four series resistors are connected across a 30 V source and carry 0.125 mA. If R1 = 10 k▲, R2 = 33 k▲ and R3 = 47 k▲, what is the value of R4? A) 15 k▲ B) 150 ▲ C) 150 k▲ D) 1.5 k▲
5)
Figure 4- 2 6) Refer to Figure 4-2a. The resistor between points E and D looks charred. What most likely would cause this? A) open A and the power supply B) short between A and B C) short between A and D D) Any of these could cause this problem.
6)
7) There is a type of analog-to-digital converter that uses a voltage divider string to perform the conversion. This type of ADC is called A) a sigma-delta converter B) a flash converter C) s series converter D) all of the above
7)
1
8) When 50 V is applied to four series resistors, 100 µA flows. If R1 = 12 k▲, R2 = 47 k▲ and R3 = 56 k ▲, what is the value of R4? A) 3.85 M▲ B) 3.85 k▲
C) 38.5 k▲
8)
D) 385 k▲
9) What is the easiest, most practical measurement performed during troubleshooting? A) resistance B) voltage C) current D) power
9)
10) If five equal resistors dissipate a total of 10 W in a series circuit, how much power does each resistor dissipate? A) 2 W B) 10 W C) 50 W D) 5 W
10)
Figure 4- 1 11) Calculate VR3 in Figure 4-1 if VT = 50 V, VR1 = 19.7 V and VR2 = 2.7 V. A) 22.4 V B) 30.3 V C) 27.6 V
11) D) 47.3 V
12) Calculate the current in Figure 4-1 if VR1 = 16 V, R1 = 10 k▲, R2 = 10 k▲ and R3 = 15 k▲. A) 12 mA B) 3.2 mA C) 1.6 mA D) 0 A
12)
13) If a 68 ▲, 33 ▲, 100 ▲ and 47 ▲ resistor are connected in series across a 9 V battery, the current equals _ . A) 327 mA B) 27.6 A C) 22.3 mA D) 36.3 mA
13)
Figure 4- 1 14) If R2 opens in Figure 4-1, the total power dissipated _ . A) will depend upon the source voltage B) remains the same C) increases to maximum D) decreases to zero 15) -1.2 V, +5 V and +6 V batteries are connected in series. The total voltage is A) 9.8 V B) 1.3 V C) 12.2 V
2
14)
. D) 1.2 V
15)
16) If a 4.7 k▲, 5.6 k▲ and 10 k▲ resistor are in series, which resistor drops the most voltage? A) the 10 k▲ resistor B) the 5.6 k▲ resistor C) the 4.7 k▲ resistor D) That can't be determined from the given information.
16)
17) What type of resistor could be used as variable voltage-divider? A) potentiometer B) rheostat C) thermistor D) any one of the above
17)
Figure 4- 1 18) Calculate IT in Figure 4-1 if R1 = 4.7 k▲, VR1 = 10 V, R2 = 4.7 k▲ and R3 = 4.7 k▲. A) 1 mA B) 6 mA C) 4.26 mA D) 2.13 mA
18)
19) An open in a series circuit results in: A) no power dissipation. C) source voltage appearing across the open.
19) B) no current flow. D) all of these.
20) If -12 V and -6 V are connected so they equal -18 V, these sources are A) connected dangerously B) in parallel C) series opposing D) series aiding
.
20)
Figure 4- 1 21) Calculate PT in Figure 4-1 if VT = 100 V and all three resistors are each 47 k▲. A) 709 mW B) 23.6 mW C) 70.9 mW 22) If 12 V and -19 V sources are connected so their total voltage is -7 V, they are A) in parallel B) connected dangerously C) series opposing D) series aiding
3
21) D) 22 W .
22)
Figure 4- 1 23) Calculate VR2 and VR3 in Figure 4-1 if VR1 = 16 V, R1 = 10 k▲, R2 = 10 k▲ and R3 = 15 k▲. A) VR2 = 16 V, VR3 = 24 V B) VR2 = 24 V, VR3 = 12 V C) VR2 = 16 V, VR3 = 16 V
23)
D) VR2 = 16 V, VR3 = 12 V
24) A 22 k▲ and 12 k▲ resistor are connected across a 68 V source. How is the voltage divided? A) 44 V and 24 V B) 34 V and 34 V C) 68 V and 68 V D) 22 V and 12 V
24)
25) If 5 V and 16 V power supplies are connected in series aiding, what is the total voltage? A) 16 V B) 21 V C) 80 V D) 24 V
25)
26) If 18 V and 6 V sources are connected in series opposing, what is the total voltage? A) 2 V B) 12 V C) 6 V D) 18 V
26)
Figure 4- 1 27) Calculate VT in Figure 4-1 if VR1 = 16 V, R1 = 10 k▲, R2 = 10 k▲ and R3 = 15 k▲. A) 56 V B) 24 V C) 16 V D) 112 V
27)
28) How much voltage is dropped across R2 and R3 in Figure 4-1 if R1 = 4.7 k▲, VR1 = 10 V, R2 = 4.7 k▲ and R3 = 4.7 k▲?
28)
A) VR2 = 10 V, VR3 = 10 V
B) VR2 = 10 V, VR3 = 4.7 V D) VR2 = 14.7 V, VR3 = 14.7 V
C) VR2 = 4.7 V, VR3 = 10 V
29) R1 = 4.7 k▲, R2 = 4.7 k▲ and R3 = 4.7 k▲ in Figure 4-1. What is RT if R2 shorts? A) 0 ▲ B) 9.4 k▲ C) 4.7 k▲ D) infinite ▲
29)
30) If a 100 ▲, 220 ▲, and 330 ▲ resistor are connected in series, total resistance equals A) the average of the three values B) 650 ▲ C) less than 100 ▲ D) 1650 ▲
30)
4
.
Figure 4- 1 31) Calculate PR2 in Figure 4-1 if VR1 =16 V, R1 = 10 k▲, R2 = 10 k▲ and R3 = 15 k▲. A) 0.0256 mW B) 25.6 mW C) 2.56 mW D) 0.256 mW
31)
32) A 50 k▲ potentiometer is connected across a 15 V source. If the voltage from the wiper to the lower end of the potentiometer is 3.2 V, what is the resistance of that lower part? A) 50 k▲ B) 39.3 k▲ C) 0 ▲ D) 10.7 k▲
32)
33) One of the most popular applications of a potentiometer is as an adjustable voltage divider also known as a: A) divider control. B) voltage control. C) current control. D) volume control.
33)
34) The voltage produced by a single solar cell is A) 0.7 V B) 18 V
34) C) 0.5 V
D) 24 V
35) Three resistors are connected in series across a 60 V source. If VR1 = 19 V and VR2 = 14.3 V, then what is the voltage drop across R3? A) 45.7 V B) 14.3 V C) 26.7 V D) 19 V
35)
36) If a 10 k▲ and 5 k▲ resistor are connected in series across a 12 V source, the voltage across the 10 k ▲ resistor is and the voltage across the 5 k▲ resistor is . A) 8 V, 8 V B) 8 V, 4 V C) 4 V, 4 V D) 4 V, 8 V
36)
37) A 500 k▲ potentiometer is connected across a 5 V source. If the voltage from the wiper to the lower end of the potentiometer is 1.2 V, what is the resistance of that lower part? A) 120 k▲ B) 500 k▲ C) 0 ▲ D) 380 k▲
37)
38) If each of the six resistors in a series circuit drops 5 V, the source voltage . A) equals 5 V B) equals 30 V C) depends on the current D) depends on the resistor values
38)
39) If three 2.2 k▲ resistors are connected in series across a 50 V source, PT equals A) 379 mW B) 402 mW C) 104.2 mW
39)
. D) 52.08 mW
40) The voltage drop across any resistor or combination of resistors in a series circuit equals: A) the product of the circuit current times the resistance value. B) the applied voltage across the resistor (A). C) the ratio of the resistance values to the total resistance times the source voltage. D) all of these.
5
40)
Figure 4- 1 41) If R2 shorts in Figure 4-1, the total circuit power A) increases C) depends upon the source voltage
. B) remains the same D) decreases
41)
Figure 4- 2 42) Refer to Figure 4-2a. Voltage from C to ground is 100 V. What is the probable cause of failure? A) short between A and B B) open between E and D C) open between A and B D) voltage reading is normal
42)
Figure 4- 1 43) VR1 = 16 V, Rn = 10 k▲, R2 = 10 k▲ and R3 = 15 k▲ in Figure 4-1. If R2 opens, then RT is _ A) 10 k▲ B) 0 ▲ C) 25 k▲ D) infinite ▲
.
43)
44) If 12 V and 17 V sources are wired in series aiding, what is the total supply voltage? A) 12 V B) 29 V C) 17 V D) 5 V
44)
45) Based upon electron current flow, the polarity on the side of the resistor where current enters is . The polarity on the side of the resistor where current exits is . A) negative, positive B) negative, negative C) positive, negative D) positive, positive
45)
6
Figure 4- 2 46) Refer to Figure 4-2a. Voltage B to ground is less than normal. What could be the cause of failure? A) open between B and C B) open between C and D C) short between A and B D) short between E and D
46)
47) Two resistors are in series across a 12 V source. If each resistor equals 470 k▲, what is the voltage across each resistor? A) 12 V B) 6 V C) 9 V D) 3 V
47)
48) Circuit ground or chassis ground can be thought of as a: A) neutral connection point. B) common point. C) reference point. D) all of these
48)
49) If R1 = 12 k▲ and R2 = 5 k▲ and they are wired in series across a 20 V source, what is VR1 and VR2?
49)
A) VR1 = 5.88 V, VR2 = 14.12 V
B) VR1 = 0 V, VR2 = 20 V
C) VR1 = 14.12 V, VR2 = 5.88 V
D) VR1 = 10 V, VR2 = 10 V
50) In a series circuit, total power PT is calculated as: A) P1 × P2 × P3 × etc.
50) B) P1 + P2 + P3 + etc. D) P1 ÷ P2 ÷ P3 ÷ etc.
C) 1/P1 + 1/P2 + 1/P3 + etc.
Figure 4- 1 51) What is the total resistance in Figure 4-1 if R1 = 10 k▲, R2 = 10 k▲ and R3 = 15 k▲? A) 0 k▲ B) 35 k▲ C) 25 k▲ D) infinite ▲
51)
52) Calculate VT in Figure 4-1 if R1 = 4.7 k▲, VR1 = 10 V, R2 = 4.7 k▲ and R3 = 4.7 k▲. A) 10 V B) 30 V C) 4.7 V D) 14.7 V
52)
7
53) In a series circuit, the largest amount of power is dissipated by: A) the smallest resistor. B) the largest resistor. C) the first resistor. D) any resistor, since the current is the same throughout the circuit.
53)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 54) Calculating current for a series resistor circuit can be accomplished with a measured voltage across one of the resistors divided by that resistor's value.
54)
55) Three 2 V cells in series with one in series-opposing would yield 2 V.
55)
56) If a 1/4 W resistor and a 1/2 W resistor are wired in series, they can safely dissipate 3/4 W.
56)
57) If a resistor is rated at 1/2 W, it can safely dissipate 0.325 W.
57)
58) A series circuit has multiple current paths.
58)
59) According to Kirchhoff's Voltage Law, the sum of the individual voltage drops in a series circuit equals the source voltage.
59)
60) Kirchhoff's Voltage Law states that the algebraic sum of all the voltages around a closed path is zero.
60)
61) If a resistor is dissipating 1/4 W, it can supply 1/4 W to the load.
61)
62) If 4.7 k▲, 2.2 k▲ and 1.2 k▲ resistors are wired in series, the total resistance is 8.7 k▲.
62)
63) Total power dissipated in a series circuit equals source voltage multiplied by current.
63)
64) In a series circuit, the current is the same at every point in the circuit.
64)
65) If 6.8 k▲, 1.2 k▲ and 5.6 k▲ resistors are wired in series, the total resistance is 13.6 k▲.
65)
66) The total power dissipated in a series circuit equals the sum of the individual powers.
66)
67) Voltage sources in series increase both voltage and current capacity.
67)
8
Answer Key Testname: CH 4
1) B 2) D 3) C 4) C 5) C 6) C 7) B 8) D 9) B 10) A 11) C 12) C 13) D 14) D 15) A 16) A 17) A 18) D 19) D 20) D 21) C 22) C 23) A 24) A 25) B 26) B 27) A 28) A 29) B 30) B 31) B 32) D 33) D 34) C 35) C 36) B 37) A 38) B 39) A 40) D 41) A 42) B 43) D 44) B 45) A 46) D 47) B 48) D 49) C 50) B 9
Answer Key Testname: CH 4
51) B 52) B 53) B 54) TRUE 55) TRUE 56) FALSE 57) TRUE 58) FALSE 59) TRUE 60) TRUE 61) FALSE 62) FALSE 63) TRUE 64) TRUE 65) TRUE 66) TRUE 67) FALSE
10
Chapter 5: Parallel Circuits MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) If the RT = 6.8 k▲ and R1 = 10 k▲ in a two-branch parallel circuit, what is the value of R2? A) 16.8 k▲ B) 3.2 k▲ C) 12 k▲ D) 21.3 k▲
1)
2) The maximum current that an analog meter movement can handle is called A) maximum scale current B) full-scale deflection current C) full-load scale current D) maximum surge current
2)
3) If four 100 W lamps are connected in parallel across a 120 V source, what is the total current? A) 8.33 A B) 3.33 A C) 833 mA D) 33.3 A
3)
4) If the power dissipation in each of four parallel branches is 1 W, PT equals A) 1 W B) 0.25 W C) 4 W
4)
. D) 0 W
5) If one resistor opens in a parallel circuit, the total circuit resistance _ and the total circuit current . A) decreases, increases B) increases, decreases C) decreases, decreases D) increases, increases
5)
Figure 5- 1 6) Refer to Figure 5-1. What is the power dissipation of R3? A) 11.4 mW B) 568 mW C) 25 mW
6) D) 284 mW
7) A three-branch parallel circuit carries a total current of 1.2 mA. If I1 = 0.2 mA and I2 = 0.7 mA, then what is the value of I3? A) 0.3 mA B) 8.7 mA C) 7.2 mA D) 2.4 mA
7)
8) IT equals 0.1 mA in a 3-branch parallel circuit. If I1 = 0.022 mA and I2 = 0.007 mA, I3 = ? A) 0.071 mA B) 0.213 mA C) 0.142 mA D) 0.029 mA
8)
9) If three 4.7 k▲ resistors are connected in parallel across a 12 V source, what is the value of PT? A) 14.1 mW B) 91.9 mW C) 1.41 W D) 141 mW
9)
1
10) If a 4.7 k▲ resistor, a 3.3 k▲ resistor and a 5.43 k▲ resistor are connected in parallel across a 50 V source, what is the current through the 5.43 k▲ resistor? A) 10.64 mA B) 4.72 mA C) 9.21 mA D) 15.15 mA
10)
11) If a 2.2 k▲ resistor, 10 k▲ resistor and 1.2 k▲ resistor are connected in parallel, the total resistance equals _ . A) 2.27 k▲ B) 13.4 k▲ C) 1.2 k▲ D) 721 ▲
11)
12) If a 500 ▲, 1200 ▲ and 10 k▲ resistor are connected in parallel across a 25 V source, how much current flows through the 1200 ▲ resistor? A) 2.5 mA B) 2.4 mA C) 20.8 mA D) 50 mA
12)
13) If you measure a lower than normal total current in a parallel circuit, . A) a resistor shorted B) all of the resistors are opened C) the power supply is off D) a resistor opened
13)
14) A short in one branch of a parallel circuit results in: A) decreased power consumption. B) increased circuit resistance. C) increased voltage drops in the remaining branches. D) increased current flow.
14)
15) A thermal image is also known as a(n) A) radiometric image C) infrared projection
15) B) hot shot D) all of the above
16) As resistors are disconnected from a parallel circuit, _ _. A) IT decreases and RT decreases B) IT decreases and RT increases C) IT increases and RT increases D) IT increases and RT decreases
16)
17) If there is 100 mA of current flowing into a three-branch parallel circuit and two of the branch currents are 40 mA and 20 mA, the third branch current is . A) 60 mA B) 40 mA C) 20 mA D) 160 mA
17)
18) If three 75 W lamps are connected in parallel across a 125 V source, IT equals A) 18 A B) 1.8 A C) 18 mA
18)
2
. D) 180 mA
Figure 5- 1 19) Refer to Figure 5-1. The voltage across R2 is 0 V. What is most likely the problem? A) R2 open B) fuse open C) R1 open D) none of the above
19)
20) If eight 47 k▲ resistors are connected in parallel across a 25 V source, RT equals . 20) A) 5.88 k▲ B) 376 k▲ C) 4.7 k▲ D) 6.71 k▲ 21) In a three-resistor parallel circuit, R1 = 0.22 M▲ and R2 = 1 M▲. If RT = 0.1166 M▲, then what is the value of R3? A) 13,400 ▲ B) 0.134 M ▲ C) 1.34 M ▲ D) 0.33 M ▲
21)
22) If a 4.7 k▲ resistor and 2.2 k▲ resistor are connected in parallel, the total resistance is A) 4700 ▲ B) 2200 ▲ C) greater than 2200 ▲ D) less than 2200 ▲
22)
.
23) In a parallel circuit, the largest amount of power is dissipated by: A) the first resistor. B) the largest resistor. C) the smallest resistor. D) any resistor, since the voltage is the same across each of the branch circuits.
23)
24) An open in one branch of a parallel circuit results in: A) decreased or reduced current flow. B) increased circuit resistance. C) decreased power consumption. D) all of these.
24)
25) A 5.2 M▲ resistor, 1.2 M▲ resistor and 1 M▲ resistor are connected in parallel across a 15 V source. What is the total current if the 1.2 M▲ resistor opens? A) 2.41 µA B) 12.5 µA C) 2.88 µA D) 17.9 µA
25)
26) If a 330 ▲ resistor, 270 ▲ resistor and 68 ▲ resistor are connected in parallel, what is the approximate value for RT? A) 668 ▲ B) 68 ▲ C) 47 ▲ D) 22 ▲
26)
27) If one resistor shorts in a parallel circuit, the total current A) decreases B) equals 0 A C) increases D) decreases momentarily, then returns to the original value
27)
3
_.
28) If one resistor opens in a parallel circuit, the total current . A) increases B) varies wildly C) decreases D) remains unchanged
28)
29) The power dissipated by any branch of a parallel circuit A) only depends on the total current B) only depends on the circuit voltage C) depends on the voltage and value of the resistor D) depends on the power rating of the resistor
29)
.
30) RT = 330 ▲ and R1 = 470 ▲ in a two-branch parallel circuit. What is the value of R2? A) 1108 ▲ B) 770 ▲ C) 194 ▲ D) 110 ▲
30)
31) If the total current equals 0 A in a four-branch parallel circuit, the trouble is that _. A) the power supply is off B) one resistor has opened C) one of the resistors has shorted D) three of the resistors have opened
31)
Figure 5- 1 32) Refer to Figure 5-1. The total current for this circuit is measured and the ammeter reads 57.8 mA. What is the problem, if any? A) R1 open B) R3 open C) R2 open D) This is normal.
32)
33) Refer to Figure 5-1. The fuse in this circuit is rated at 100 mA. Would the fuse blow if an additional 1 k▲ were placed in parallel with R5? A) no B) yes C) Fuse has nothing to do with this part of the circuit.
33)
34) The total resistance of a three-branch parallel circuit is 76.92 ▲. If R1 = 100 ▲ and R2 = 500 ▲, what is the value of R3? A) 1000 ▲ B) 140 ▲ C) 1850 ▲ D) More information is needed to calculate R3.
34)
35) If twelve 1.5 M▲ resistors are connected in parallel across 50 V, RT equals A) 1.5 M ▲ B) 1 M▲ C) 1.25 M▲
35)
. D) 0.125 M▲
36) In a three-branch parallel circuit, R1 = 1.2 M▲, R2 = 1 M▲ and RT = 0.5 M▲. Calculate R3. A) 7.7 M▲ B) 6 M▲ C) 1.7 M▲ D) 2 M▲
4
36)
37) To measure the current through one branch of a parallel circuit, the meter is connected A) in series with the branch resistor B) in parallel with the branch resistor C) across the source D) in series with the source 38) In a parallel circuit, total power PT is calculated as: A) 1/P1 + 1/P2 + 1/P3 + etc.
.
37)
38) B) P1 + P2 + P3 + etc.
C) P1 × P2 × P3 × etc.
D) P1 ÷ P2 ÷ P3 ÷ etc.
39) If you want to measure a load voltage with a DVM, connect the meter . A) across the source B) in parallel with the load C) in series with the load D) in series with the source
39)
40) If three 22 k▲ resistors are connected in parallel across a 10 V source, PT equals . A) 22.6 m W B) 18.1 m W C) 4.5 m W D) 13.6 m W
40)
41) The current through any branch of a parallel circuit A) is inversely proportional to the branch resistance B) is directly proportional to the branch resistance C) depends only on the circuit voltage D) depends on the power rating of the resistor
41)
.
42) As additional branch resistors are connected in a parallel circuit, . A) IT increases and RT decreases B) IT decreases and RT increases C) IT decreases and RT decreases D) IT increases and RT increases
42)
Figure 5- 1 43) Refer to Figure 5-1. To accurately measure the total current for this circuit, how must the ammeter be connected? A) between the positive terminal and the fuse B) between R1 and the fuse C) between the negative terminal and the supply and ground D) either A or C
43)
44) If a 1 M▲ resistor, 0.47 M▲ resistor and 0.5 M▲ resistor are connected in parallel across an 18 V source, what is the total current if the 1 M▲ resistor opens? A) 92.3 µA B) 92.3 mA C) 74.3 mA D) 74.3 µA
44)
5
45) If 5 A and 3 A enter a junction from two separate paths, how much current flows out of the junction? A) 8 A B) 2 A C) 3 A D) the larger of the two
45)
46) Each branch in a four-branch parallel circuit carries 10 mA. If one of the branches opens, then the current in each of the other three branches equals . A) 0 A B) 30 mA C) 10 mA D) 13.33 mA
46)
47) A formula that applies to a two-branch parallel circuit is . A) IT = IR1 + IR2 B) VT = VR1 + VR2
47)
C) RT = V1 ÷ R2
D) RT = R1 + R2
48) A two-branch parallel circuit contains these values: R1 = 1200 ▲, IT = 0.005 mA, I2 = 0.003 mA. What is the value of VR1? A) 2.4 m V B) 6 m V C) 18 m V D) 3.6 m V
48)
49) If a 470 ▲ resistor, 680 ▲ resistor and 830 ▲ resistor are connected in parallel, the total resistance equals _ . A) 1150 ▲ B) 1980 ▲ C) 1510 ▲ D) 208 ▲
49)
50) The most popular application for a parallel circuit in electronics is as a: A) current divider. B) resistance divider. C) power divider. D) voltage divider.
50)
51) If a 2.2 k▲ resistor and a 3.3 k▲ resistor are connected in parallel, RT equals A) 2.2 k▲ B) 3.3 k▲ C) greater than 2.2 k▲ D) less than 2.2 k▲ 52) If a 5.5 k▲, 22 k▲ and 500 ▲ resistor are connected in parallel, what is RT? A) 27.6 k▲ B) 449 ▲ C) 28.1 k▲
.
51)
52) D) 330 ▲
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 53) PR1 = 0.25 W and PR2 = 1.2 W in a parallel circuit. The total power dissipated is 1.25 W.
53)
54) If one branch of a parallel circuit opens, the total resistance decreases.
54)
55) If IR1 = 75 mA and IR2 = 12.7 mA in a two branch parallel circuit, IT = 85.7 mA.
55)
56) Kirchhoff's Current Law states that the sum of the currents into a junction must equal the sum of the currents out of that junction.
56)
57) The total resistance of four resistors in parallel is always less than the smallest resistance.
57)
58) Measurement of total current is accomplished with the ammeter in series with the source voltage.
58)
59) Accurate troubleshooting of a parallel circuit cannot be performed with a voltmeter.
59)
6
60) The total power dissipated by a parallel circuit can be found by adding the individual powers.
60)
61) If three equal resistors are connected in parallel across 12 V, each resistor drops 4 V.
61)
62) A parallel circuit can be easily identified because only one end of each component is connected to each other.
62)
63) If IR1 = 0.065 mA and IR2 = 0.098 mA in a two branch parallel circuit, IT = 0.163 mA.
63)
64) Total power for a parallel circuit can be determined by the same method as a series circuit.
64)
65) The total resistance of three parallel resistors equals the sum of the individual resistor values.
65)
66) If one branch of a parallel circuit shorts, the total resistance decreases.
66)
7
Answer Key Testname: CH 5
1) D 2) B 3) B 4) C 5) B 6) D 7) A 8) A 9) B 10) C 11) D 12) C 13) D 14) D 15) A 16) B 17) B 18) B 19) B 20) A 21) D 22) D 23) C 24) D 25) D 26) C 27) C 28) C 29) C 30) A 31) A 32) B 33) A 34) A 35) D 36) B 37) A 38) B 39) B 40) D 41) A 42) A 43) D 44) D 45) A 46) C 47) A 48) A 49) D 50) A 8
Answer Key Testname: CH 5
51) D 52) B 53) FALSE 54) FALSE 55) FALSE 56) TRUE 57) TRUE 58) TRUE 59) TRUE 60) TRUE 61) FALSE 62) FALSE 63) TRUE 64) TRUE 65) FALSE 66) TRUE
9
Chapter 6: Series-Parallel Circuits MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Figure 6- 5 1) Refer to Figure 6-5. If all of the resistors of this circuit are 5 k▲ and VS1 and VS2 are 10 V but opposing polarities, what would be the current flow through R2? A) 13.33 mA B) 0 A C) 1.33 mA D) 2.66 mA
1)
Figure 6- 3 2) If a fifth 10 k▲ resistor is connected in series in Figure 6-3, how does VR4 change? A) VR4 decreases. C) VR4 increases.
2)
B) VR4 remains the same. D) VR4 increases to 10 V.
Figure 6- 1 3) If R1 = 10 k▲, R2 = 15 k▲ and R3 = 50 k▲ in Figure 6-1, RT equals A) 10 k▲ B) 21.5 k▲ C) 9.5 k▲
.
3) D) 11.5 k▲
4) The parallel combination of a 330 ▲ resistor and a 470 ▲ resistor is connected in series with the parallel combination of four 1 k▲ resistors. If a 100 V source is connected across the circuit, then which resistor carries the most current? A) 470 ▲ B) 1 k▲ C) 330 ▲
1
4)
Figure 6- 3 5) If Vs = 40 V and R3 opens in Figure 6-3, what is the value of VR3? A) 30 V B) 0 V C) 40 V D) 20 V
5) E) 10 V
Figure 6- 1 6) In Figure 6-1, R1 is connected in
.
6)
A) series with R3 B) series with R2 C) parallel with R3 D) parallel with R2 E) none of the above 7) The Wheatstone bridge circuit is widely used to measure: A) precise resistances. B) exact voltages. C) accurate currents. D) all of these.
7)
Figure 6- 4 8) Refer to Figure 6-4. With circuit balanced there is: A) no current flow through the total circuit. B) maximum current flow through the load. C) Cannot be determined without detailed analysis. D) no current through the load.
2
8)
Figure 6- 1 9) If Vs = 20 V, R1 = 10 k▲, R2 = 50 k▲ and R3 = 15 k▲ in Figure 6-1, PR2 equals A) 2.30 mW B) 18.6 mW C) 8.63 mW
. D) 7.64 mW
9)
10) If four parallel 10 k▲ resistors are in series with a single 20 k▲ resistor and one of the parallel resistors shorts, the voltage across the other parallel resistors _. A) remains the same B) increases C) decreases
10)
Figure 6- 3 11) If a 10 k▲ resistor is placed in parallel with R4 in Figure 6-3, how will VR4 change? A) VR4 will increase. C) VR4 will remain the same.
11)
B) VR4 will change to 4 volts. D) VR4 will decrease.
Figure 6- 2 12) If all of the resistors in Figure 6-2 are 4.7 k▲, what is the value of RT? A) 12.5 k▲ B) 4.7 k▲ C) 18.8 k▲
12) D) 9.4 k▲
13) In a two-source circuit, one source alone produces 10 mA through a branch. If the other source alone produces 8 mA in the opposite direction through the same branch, what is the total current through the branch? A) 2 mA B) 8 mA C) 10 mA D) 18 mA
3
13)
Figure 6- 2 14) If R3 shorts in Figure 6-2, VR5 A) increases
. B) remains the same
14) C) decreases
Figure 6- 4 15) Refer to Figure 6-4. What approximate R1 resistor value would it take to balance this bridge circuit? A) 330 ▲ B) 560 ▲ C) 825 ▲ D) 680 ▲
15)
16) According to the maximum power transfer theorem, maximum power is delivered to any load when the load resistance is: A) exactly equal to the source resistance. B) larger than source resistance. C) at least twice or more than the source resistance. D) less than one-half of the source resistance.
16)
Figure 6- 3 17) If Vs = 12 V in Figure 6-3, what is the value of VEB if R3 shorts? A) 6 V
B) -3 V
C) -8 V
18) If Vs = 22 V in Figure 6-3, what is the is the value of VDB? A) 5.5 V B) 11 V C) -22 V
4
17) D) 8 V 18) D) -11 V
19) In solving series-parallel circuits using Ohm's law, first solve for: A) RT. B) IT. C) ET. D) any of these, it doesn't matter.
19)
Figure 6- 1 20) If R3 opens in Figure 6-1, VR1 A) remains the same C) decreases
.
20) B) decreases to zero D) increases
21) In the parallel portion of series-parallel circuits, the total resistance is: A) less than any one resistance. B) equal to the smallest resistance. C) greater than the largest resistance. D) less than the smallest resistance.
21)
Figure 6- 5 22) Refer to Figure 6-5. Determine the amount of current flow through R2 with the following component parameters. VS1 = 10 V, VS2 = 3 V, R1 = 2 k, R2 = 3 k, and R3 = 700 A) 1 mA B) 5.3 mA C) 1.37mA D) 0 A
22)
23) In the series portion of series-parallel circuits, the total resistance is: A) less than any one resistance. B) less than the largest resistance. C) equal to the largest resistance. D) greater than the largest resistance.
23)
Figure 6- 3 24) If VR1 = 15 V in Figure 6-3, what is the value of VBD? A) 60 V B) -60 V C) 30 V
5
24) D) -30 V
25) If VR4 = 10 V in Figure 6-3, what is the value of VAD? A) 30 V B) 40 V C) 10 V
25) D) 20 V
Figure 6- 2 26) If Vs = 15 V and every resistor equals 2.2 k▲ in Figure 6-2, what is the value of IR4? A) 0.85 mA B) 2.55 mA C) 5.11 mA D) 0.42 mA
26)
27) The difference between a balanced and an unbalanced Wheatstone bridge is measured by: A) a galvanometer. B) an ohmmeter. C) an ammeter. D) a voltmeter.
27)
Figure 6- 3 28) What is the resistance between points A and D in Figure 6-3? A) 20 k▲ B) 30 k▲ C) 10 k▲
28) D) 40 k▲
Figure 6- 1 29) If R1 = 4.7 k▲, R2 = 3.3 k▲, R3 = 1 k▲ and Vs = 50 V in Figure 6-1, IT equals A) 75.7 mA B) 9.15 mA C) 12.1 mA
. D) 8.8 mA
30) If R1 = 4.7 k▲, R2 = 3.3 k▲ and R3 = 1 k▲ in Figure 6-1, the total resistance equals _ _. A) 5467 ▲ B) 660 ▲ C) 4125 ▲ D) 5700 ▲
6
29)
30)
31) In solving series-parallel circuits, the last and easiest to solve for is: A) PT. B) RT. C) ET.
31) D) IT.
Figure 6- 3 32) If Vs = 50 V in Figure 6-3, what is the value of VCA? A) 25 V B) -25 V
32) C) 5 V
D) -5 V
33) The super position theorem provides a method for: A) analyzing complex series-parallel circuits. B) building complex series-parallel circuits. C) designing complex series-parallel circuits. D) all of these.
33)
Figure 6- 2 34) If all resistors equal 4.7 k▲ and Vs equals 20 V in Figure 6-2, what is the value of IR3? A) 0.53 mA B) 12.5 mA C) 1.06 mA D) 11.99 mA
34)
35) Two series 1 k▲ resistors are connected in parallel with a 2.2 k▲ resistor. If the voltage across one of the 1 k▲ resistors is 6 V, what is the voltage across the 2.2 k▲ resistor? A) 13.2 V B) 3 V C) 6 V D) 12 V
35)
7
Figure 6- 3 36) If the current is 12 mA in Figure 6-3, what is the value of VEB? A) 360 V B) 240 V C) -240 V
36) D) -360 V
Figure 6- 1 37) In Figure 6-1, R2 is connected in
.
37)
A) series with R1 C) series with R3
B) parallel with R3 D) parallel with R1
38) Power in a series-parallel resistor circuit is dissipated as: A) heat. B) current flow. C) voltage loss. D) resistance change.
38)
Figure 6- 2 39) If R1 = 50 k▲, R2 = 10 k▲, R3 = 10 k▲, R4 = 50 k▲ and R5 = 10 k▲ in Figure 6-2, what is the value of RT? A) 8.57 k▲ B) 85.7 k▲ C) 130 k▲ D) 68.6 k▲
39)
40) If every resistor in Figure 6-2 equals 2.2 k▲, what is the value of RT? A) 5.87 k▲ B) 2.2 k▲ C) 5.5 k▲
40)
8
D) 4.4 k▲
41) If a voltage divider consists of two 10 k▲ resistors, which one of these load resistors will change the output voltage the most? A) 10 k▲ B) 20 k▲ C) 100 k▲ D) 1 M▲
41)
Figure 6- 3 42) If the current is 1.2 mA in Figure 6-3, what is the value of PT? A) 0.576 mW B) 57.6 mW C) 5.76 mW
D) 576 mW
42)
43) What is the resistance between points B and E in Figure 6-3? A) 20 k▲ B) 30 k▲ C) 40 k▲
D) 10 k▲
43)
Figure 6- 2 44) If R4 shorts in Figure 6-2, VR5 A) increases C) decreases to zero
.
45) If R1 shorts in Figure 6-2, VR4 A) equals VR2 C) increases
.
44) B) remains the same D) decreases 45) B) decreases D) remains the same
Figure 6- 1 46) If Vs = 25 V, R1 = 10 k▲, R2 = 15 k▲ and R3 = 50 k▲ in Figure 6-1, IT equals A) 2.5 mA B) 1.16 mA C) 2.17 mA
9
. D) 1.58 mA
46)
Figure 6- 3 47) If VR3 = 17 V in Figure 6-3, what is the value of P1? A) 1.7 mW B) 17 mW
47) C) 2.89 W
D) 28.9 mW
Figure 6- 2 48) In Figure 6-2 if R1 = 10 k▲, R2 = 4.7 k▲, R3 = 4.7 k▲, R4 = 10 k▲ and R5 = 4.7 k▲, RT = ? A) 18.3 k▲ B) 6.1 k▲ C) 24.7 k▲ D) 0 ▲
48)
49) Thevenin's theorem provides a method for: A) simplifying complex series-parallel circuits. B) building complex series-parallel circuits. C) designing complex series-parallel circuits. D) all of these.
49)
Figure 6- 2 50) In Figure 6-2, R3 and R4 are connected in
.
A) series with each other and R5 C) series with each other and R1 and R2
50) B) parallel with R1 and R2 D) series with each other
51) One Ohm's law formula PT = P1 + P2 + etc. can be used to solve for total power in: A) parallel circuits. B) series-parallel circuits. C) series circuits. D) all of these.
10
51)
Figure 6- 2 52) If R2 opens in Figure 6-2, VR3 A) causes the fuse to blow C) remains the same
.
52) B) increases D) decreases
53) The parallel combination of a 330 ▲ resistor and a 470 ▲ resistor is connected in series with the parallel combination of four 1 k▲ resistors. If a 100 V source is connected across the circuit, then which resistor drops the most voltage? A) 330 ▲ B) 470 ▲ C) 1 k▲
53)
54) In solving series-parallel circuits using Ohm's law, first solve for: A) the parallel current. B) the series resistance. C) the parallel resistance. D) the series current.
54)
Figure 6- 4 55) Refer to Figure 6-4. If R1 is changed to 500 ▲, the Thevenin resistance and voltage would be: A) 1 k and 807 mV. B) 1 k and 3 V. C) 595 and 3 V. D) 595 and 807 mV.
11
55)
Figure 6- 2 56) In Figure 6-2, R3 and R4 are connected in
.
56)
A) series with R5 B) parallel with each other C) series with R2 D) series with each other and in parallel with R5 57) If four parallel 10 k▲ resistors are connected in series with a single 20 k▲ resistor and one of the parallel resistors opens, how does the voltage across the other parallel resistors change? A) It decreases. B) It remains the same. C) It increases.
57)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 58) Two or more resistors connected in series form a circuit known as a voltage divider.
58)
59) A loaded voltage divider is a series- parallel circuit.
59)
Figure 6- 1 60) R1 is in series with R3 in Figure 6-1.
60)
61) Thevinizing a circuit creates an equivalent series circuit.
61)
62) If two resistors are in parallel, they drop the same voltage.
62)
63) A bridge circuit's resistances must all be of the same value to be in a balanced condition.
63)
12
Figure 6- 1 64) R1 is in series with the series combination R2 and R3 in Figure 6-1.
64)
65) R1 is in series with the parallel combination R2 and R3 in Figure 6-1.
65)
66) A voltmeter, when connected across a component, can be viewed as being a resistor in series with that component.
66)
67) The voltage across any open in a series-parallel circuit will be the source voltage.
67)
68) A series- parallel circuit consists of resistors in both series and parallel.
68)
69) No problems could occur if a 10 V source and a 20 V source were connected in parallel.
69)
70) Maximum power is achieved when the load resistance is approximately two times the source resistance.
70)
71) If two resistors are in parallel, they carry the same current.
71)
72) The superposition theorem applies only to electronic or electrical circuits with two or more sources.
72)
Figure 6- 1 73) R2 is in parallel with R3 in Figure 6-1.
73)
13
Answer Key Testname: CH 6
1) B 2) A 3) B 4) C 5) C 6) E 7) A 8) D 9) A 10) C 11) D 12) A 13) A 14) C 15) C 16) A 17) C 18) D 19) A 20) C 21) D 22) C 23) D 24) C 25) A 26) A 27) A 28) B 29) B 30) A 31) A 32) B 33) A 34) A 35) D 36) D 37) B 38) A 39) D 40) A 41) A 42) B 43) B 44) D 45) C 46) B 47) D 48) A 49) A 50) D 14
Answer Key Testname: CH 6
51) D 52) D 53) C 54) C 55) C 56) D 57) C 58) TRUE 59) TRUE 60) FALSE 61) TRUE 62) TRUE 63) FALSE 64) FALSE 65) TRUE 66) FALSE 67) FALSE 68) TRUE 69) FALSE 70) FALSE 71) FALSE 72) FALSE 73) TRUE
15
Chapter 7: Magnetism and Electromagnetism MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) If a relay picks up and makes a contact but does not stay picked up, what's the trouble? A) The magnetic field is too weak. B) The relay coil is open. C) The magnetic field is too strong. D) There is no trouble. The relay is operating normally.
1)
2) A _ is a type of electromagnetic device that has a movable iron core called a plunger. A) relay B) solenoid C) speaker D) analog meter
2)
3) If a higher voltage is needed from a generator, what must be done? A) Turn the coil faster. B) Increase the distance between the coil and magnetic field. C) Decrease the number of coils. D) both B and C.
3)
4) Hysteresis is a characteristic of magnetic materials wherein a change in magnetization: A) occurs after the application of a magnetic force. B) varies according to the current flow. C) occurs exactly with the application of a magnetic force. D) occurs before the application of a magnetizing force.
4)
5) A weber is a unit of . A) magnetic flux C) magnetomotive force
5) B) permeability D) reluctance
6) A tesla is a unit of . A) magnetic flux density C) magnetomotive force
B) reluctance D) permeability
7) Proximity detectors usually use a A) reed C) solenoid
6)
switch in conjunction with a magnet. B) normally closed D) optical
7)
8) Induced voltage resulting from electromagnetic induction is proportional to: A) the number of turns of wire in the coil. B) the rate at which the conductor and magnetic fields move relative to each other. C) the angle at which the conductor cuts the magnetic field. D) all of these.
8)
9) The magnetic term that is equivalent to voltage is _ A) flux density C) current
9)
. B) magnetomotive force D) reluctance
1
10) Unlike magnetic poles A) repel, attract
and like poles B) attract, attract
. C) repel, repel
10) D) attract, repel
11) Electromagnetic induction is best defined as the process by which a voltage is produced in a conductor when there is: A) motion between the conductor and the magnetic field. B) motion around the magnetic fields. C) energy produced by the rotating coils. D) motion between the magnetic poles.
11)
12) The polarity of an induced voltage depends on the . A) amount of current flowing B) direction of motion of a conductor in a magnetic field C) time that the conductor remains stationary in a magnetic field D) length of a conductor in a magnetic field
12)
13) Applying an ac voltage to an electromagnet's coil will produce a . A) north magnetic field B) changing magnetic field C) south magnetic field D) steady magnet field
13)
14) Increasing the speed at which a magnet moves through a coil of wire causes the induced voltage to . A) decrease B) remain the same C) increase
14)
15) Faraday's law and Lenz's law are related in that they deal with: A) a resulting current flow. B) varying magnetic field. C) an induced voltage. D) all of these.
15)
16) An iron core electromagnet has a higher A) resistance B) reactance
16)
than an air core electromagnet. C) permeability D) current
17) If the contacts fail to open when a relay is de-energized, what is the trouble? A) The return spring tension is too large. B) Dirt is causing the relay armature to stick. C) There is too little current in the relay coil. D) There is no trouble. The relay is operating normally. 18) The amount of voltage that is induced in a conductor depends on the _ A) direction of motion of the conductor in the magnetic field B) direction of the current flowing C) length of time a conductor remains stationary in the magnetic field D) length of the conductor in the magnetic field
17)
.
18)
19) The term reluctance in magnetic circuits is like the term in electrical circuits. A) current B) resistance C) capacitance D) voltage
19)
20) Soft iron has a high A) reactance
20)
. B) resistance
C) permeability
2
D) mmf
21) The quantity of lines of force per unit of area is known as . A) flux density B) ampere-turns C) permeability
21) D) magnetic flux
22) A relay is a device that _. A) has a coil to actuate some contacts that control other circuits B) uses an electromagnet to open and close contacts C) isolates the actuating signal from the control signal D) all of these 23) The permeability of air is A) 22
. B) 19.2
22)
23) C) 1
D) 7
24) How does the magnetic field change around a conducting wire if the current increases? A) It is impossible to predict. B) There is no magnetic field around a conducting wire. C) The field grows stronger. D) The field grows weaker.
24)
25) The principal difference between a solenoid and a relay is that: A) relays relay electricity, solenoids do not. B) solenoids do mechanical work, relays do electrical work. C) relays use magnets, solenoids do not. D) solenoids do electrical work, relays do mechanical work.
25)
26) A solenoid consists of _ . A) a burglar alarm relay C) two plates separated by an insulator
26) B) a coil of wire wound around a core D) a permanent magnet
27) Like magnetic poles . A) have the same current through them C) have no effect on each other
B) repel each other D) attract each other
28) The movable part of the solenoid is the: A) the plunger. C) magnetic field.
B) electromagnetic coil. D) all of these.
27)
28)
29) If a basic one-loop, dc generator rotates at 60 revolutions each second, how many times each second does its dc output voltage reach a peak value? A) 60 B) 240 C) 0 D) 120
29)
30) The purpose of a commutator in a dc generator is to: A) keep current flowing in one direction. C) maximize the current generated.
30) B) provide filtration. D) concentrate flux density.
31) An ampere- turn is a unit of A) permeability C) reactance
B) resistance D) magnetomotive force (mmf)
.
31)
3
32) Permeability is . A) the opposition to being magnetized B) the shielding effect of a material C) the ease of a material to be magnetized D) the ability of a magnetic material to conduct a current
32)
33) According to the left- hand rule for the magnetic field around a conductor, what points in the direction of current flow? A) fingers B) index finger C) meter D) thumb
33)
34) Faraday's law states that the voltage induced across a coil of wire is proportional to these two factors. A) the diameter of the conductor and the rate of change of the magnetic flux B) the size of the magnets and the rate of change of the magnetic flux C) the number of turns in the coil and the rate of change of the magnetic flux D) the size of the coil and the rate of change of the magnetic flux
34)
35) The A) open
35)
electromagnet cannot be further magnetized. B) saturated C) shorted
D) capacitive
36) When controlling the direction of a dc motor, which winding(s) have their polarity reversed? A) both the stator and the armature B) either the stator or the armature C) only the stator D) only the armature
36)
37) If a tape recorder's output voltage increases and decreases when you shake the recorder, a possible problem might be _ _. A) too high a source voltage B) a loose circular magnet around the speaker's voice coil C) an open circuit in the speaker D) an open capacitor
37)
38) If two north magnetic poles are brought close to each other, . A) a current is induced B) a force of repulsion pushes them apart C) a force of attraction pulls them together D) an electromagnet is created
38)
39) Magnetic lines that are close to each other are said to have a high _ A) current B) flux density C) inductance
39)
40) The movable part of the relay is the: A) the armature. C) electromagnetic coil. 41) A simple electric doorbell probably uses A) a permanent magnet C) an electromagnet
. D) reluctance
40) B) magnetic field. D) all of these. to ring the bell. B) a DPDT switch D) transistor
42) The magnetic field around an electromagnet is produced by . A) the conductor's permeability B) a permanent magnet C) a current flowing through the winding D) the laminated iron core
4
41)
42)
43) The voltage produced by a magnetic field cutting through a conductor depends on the A) direction of motion B) length of the conductor C) speed of motion D) all of the above
.
43)
44) For a high current switching application where it is not practical to route heavy wiring to the switch location which device would be used? A) relay B) solenoid C) generator D) electromagnet
44)
45) Which one of the statements below does NOT apply to the voltage induced into a wire when it is moved through a magnetic field? A) It depends on the length of moving wire in the field. B) It depends on the speed of wire motion. C) It depends on the strength of the magnetic field. D) It depends on the current flowing in the wire.
45)
46) A coil of wire with current flowing through it is called a(n) . A) south pole B) electromagnet C) north pole
46) D) capacitor
47) If more turns of wire are added to a coil and then that coil is moved through a magnetic field, the voltage produced will _ . A) be less than the original coil B) be more than the original coil C) be the same as the original coil
47)
48) How will two permanent bar magnets react if they are brought close to each other? A) They will repel if the north and south poles are together. B) They will attract if their north poles are together. C) They will attract if the north and south poles are together. D) They will attract if their south poles are together.
48)
49) Reversing the current through an electromagnet A) reverses B) increases
49)
the magnetic field. C) collapses
D) decreases
50) If the number of turns of wire on an electromagnet increases, the magnetomotive force mmf . A) increases B) remains the same C) decreases
50)
51) If some turns of wire are removed from an electromagnet, the magnetic field will A) be the same as the original electromagnet B) be less than the original electromagnet C) be more than the original electromagnet
.
51)
52) If the cross-sectional area of a magnetic field decreases, the flux density . A) decreases B) increases C) remains the same
52)
53) Why is a vibrating wire strain gage appropriate for damp environments? A) it is a sealed unit B) strain is not affected by humidity C) frequency is not affected by humidity D) all of the above
53)
5
54) In which one of the following applications is electromagnetism used? A) loudspeakers B) tape recorders C) relays
54) D) all of these
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 55) A solenoid converts electrical energy into mechanical energy.
55)
56) A conductor with no current through it will still have a magnetic field around it.
56)
57) A magnetic field around a conductor is a good indication that current is flowing.
57)
58) A DC generator produces a smooth DC voltage output.
58)
59) Two north magnetic poles attract one another.
59)
60) Unlike magnetic poles repulse one another.
60)
61) Flux lines are concentrated at the center of a magnet.
61)
62) Aluminum, brass, and iron make good magnets.
62)
63) A strong magnetic field around a conductor indicates a small current flowing through the conductor.
63)
64) Soft iron, copper, and silver make good magnets.
64)
65) The opposition to being magnetized is called permeability.
65)
66) The speed of movement of the coil of a generator affects the direction of current produced.
66)
67) A permanent magnet will retain its magnetism for a long period of time.
67)
68) The left-hand rule can be used to determine the amount of magnetomotive force.
68)
69) Magnetic flux is another name for a magnetic field.
69)
6
Answer Key Testname: CH 7
1) A 2) B 3) A 4) A 5) A 6) A 7) A 8) D 9) B 10) D 11) A 12) B 13) B 14) C 15) D 16) C 17) B 18) D 19) B 20) C 21) A 22) D 23) C 24) C 25) B 26) B 27) B 28) A 29) D 30) A 31) D 32) C 33) D 34) C 35) B 36) B 37) B 38) B 39) B 40) A 41) C 42) C 43) D 44) A 45) D 46) B 47) B 48) C 49) A 50) A 7
Answer Key Testname: CH 7
51) B 52) B 53) A 54) D 55) TRUE 56) FALSE 57) TRUE 58) FALSE 59) FALSE 60) FALSE 61) FALSE 62) FALSE 63) FALSE 64) FALSE 65) FALSE 66) FALSE 67) TRUE 68) FALSE 69) TRUE
8
Chapter 8: Introduction to Alternating Current and Voltage MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The largest numerical value in the measurement of alternating current is: A) peak. B) average. C) rms.
1) D) peak to peak.
Figure 8- 2 2) Calculate the total power dissipation in the circuit in Figure 8-2. A) 45.6 mW B) 9.12 mW C) 182 mW
2) D) 64.5 mW
3) An oscilloscope's volts/division switch is set on 50 mV/div. If the vertical deflection of the oscilloscope's trace is 1.6 division, what voltage is being measured? A) 50 mV B) 80 mV C) 1.6 mV D) 0.008 V
3)
Figure 8- 2 4) In Figure 8-2, what is the instantaneous voltage across R1 at 122°? A) 5.8 V B) 18.2 V C) 11.2 V
D) 11.6 V
4)
5) Calculate IT in Figure 8-2. A) 9.12 mAPP
D) 3.22 mAPP
5) B) 6.44 mAPP
C) 4.55 mAPP
1
Figure 8- 1 6) In Figure 8-1, the time from point C to E is called A) a half-cycle B) a cycle
. C) the period
6) D) peak voltage
7) What type of sensor is used by a clamp meter to measure dc current? A) inductive B) inverter C) transformer action D) Hall-effect
7)
8) The time (T) and the frequency (f) of an AC waveform are related as: A) directly proportional. B) universally proportional. C) inversely proportional. D) complimentary proportional.
8)
9) The symbol for the period of a wave form is: A) F. B) W.
9)
10) The RMS value of a sine wave means A) the same as IP × R
C) T.
D) P.
.
10)
B) the same as IPP × R C) the heating effect of an ac generator of the same voltage D) the root mean square value
Figure 8- 2 11) Calculate VR2 in Figure 8-2. A) 6.84 VPP B) 4.84 VP
11) C) 6.84 VP
12) The period of most AC waveforms is measured in units of: A) seconds. B) revolutions. C) alternations.
2
D) 13.15 VP 12) D) cycles.
Figure 8- 1 13) Which point in Figure 8-1 is 180° away from point E? A) A B) B C) C
13) D) D
14) A signal source that can produce custom waveforms is called a(n) A) arbitrary function generator B) multifunction signal generator C) custom-pattern generator D) all of the above
14)
15) A 10 VP sine wave is equal to _ A) 100 VPP C) 5 VPP
15)
. B) 20 VPP D) none of the above
Figure 8- 1 16) VPP is measured between points A) G and I B) C and H
in Figure 8-1. C) A and B
17) If a 10 k▲ resistor carries 5 mARMS of current, its voltage drop equals A) 7.07 VRMS B) 50 VRMS C) 5 VRMS
16) D) D and F _.
17) D) 70.7 VRMS
18) A square wave is a unique form of the rectangular pulse wave in that: A) the wave is symmetrical. B) the duty cycle is 50%. C) the positive and negative halves are equal. D) all of these
18)
19) A 60 Hz sine wave completes A) 600 B) 10
19)
cycles every 10 seconds. C) 6
3
D) 1/16
20) The square wave is made up of: A) just the fundamental frequency. B) the fundamental frequency and all the odd harmonics. C) the fundamental frequency and both the odd and even harmonics. D) the fundamental frequency and all the even harmonics.
20)
21) Superimposed DC and AC voltages mean the two voltages are combined: A) in parallel aiding or opposing. B) in series aiding or opposing. C) in series-parallel aiding or opposing. D) all of these
21)
22) What is the instantaneous voltage at 42° on a 230 VP sine wave? A) 115 V B) 149 V C) 154 V
22)
23) The formula to convert degrees to radians is: L rad A) radians= × degrees. 180° C) degrees =
D) 76.1 V 23)
B) 180° = L radians.
180° × radians. L rad
D) all of these.
Figure 8- 2 24) In Figure 8-2, if you look at VR1 with an oscilloscope and you find no trace, a possible trouble might be that _. A) R2 is shorted C) R2 is open
24)
B) R1 is open D) the resistance of R2 has changed
25) If you want to test a system for its frequency response you would probably employ a(n) A) custom-pattern generator B) multifunction signal generator C) swept-frequency oscillator D) arbitrary function generator
25)
26) An oscilloscope's seconds/division switch is set on 20 ms/div. If a sine wave measures 4 divisions horizontally, what frequency is being measured? A) 50 Hz B) 12.5 Hz C) 25 Hz D) More information is needed.
26)
27) A 12 VP sine wave equals _ . A) 7.64 VAVG B) 24 VPP
27) C) 8.48 VRMS
4
D) all of these
28) Spectrum analyzers A) are frequency-domain devices B) display the sinusoidal components of a waveform C) are used primarily in RF and microwave applications D) all of the above
28)
Figure 8- 2 29) VR2 if R1 opens in Figure 8-2. A) decreases B) increases
29) C) remains the same
30) Troubleshooting an AC circuit can be performed with which of the following tools? A) oscilloscope B) digital multimeter C) analog voltmeter D) any of the above
30)
Figure 8- 2 31) What is the approximate peak input voltage to the circuit in Figure 8-2? A) 10 VP B) 20 VP C) 14.1 VP
31) D) 28.3 VP
32) While troubleshooting a circuit the voltage seems to be zero; what if any adjustment should be checked on the oscilloscope? A) AC/GND/DC switch B) time division setting C) trigger level D) focus setting
5
32)
Figure 8- 2 33) Find RT in Figure 8-2. A) 6.2 k▲
33) B) 4.77 k▲
C) 1.13 k▲
D) 4.7 k▲
Figure 8- 1 34) Which of the following can be measured from points B to F in Figure 8-1? A) the period B) the peak-to-peak voltage C) the frequency D) the angle
34)
Figure 8- 3 35) This display in Figure 8-3 illustrates maladjustment of which control on the oscilloscope? A) coupling B) intensity C) trigger level D) volts/div
6
35)
Figure 8- 2 36) In Figure 8-2, what is the instantaneous voltage across R1 at an angle of 22°? A) 20.3 V B) 8.03 V C) 12.0 V
36) D) 2.56 V
Figure 8- 1 37) Which one of the following represents the value at point G in Figure 8-1? A) the RMS voltage B) the peak voltage C) the frequency D) the period
37)
38) The average value of a rectangular pulse wave is calculated as: A) Vavg = 0.637 Vp. B) Vavg = Vbaseline + Vp. C) Vavg = 1.57 Vp. D) Vavg = Vbaseline + (duty cycle) × Vp.
38)
39) What is the instantaneous voltage at 17° on a 169 VP sine wave? A) 161 V B) 80.5 V C) 98.8 V
39)
40) Traditionally, radio frequency signal generators operate in the range of A) 100 kHz to 5 GHz B) 100 kHz to 1 GHz C) 500 kHz to 5 GHz D) 10 kHz to 1 GHz
7
D) 49.4 V 40)
Figure 8- 1 41) In Figure 8-1, which of the following can be measured from point E to point F? A) the peak to peak voltage B) one cycle of voltage C) the RMS voltage D) the peak voltage
41)
42) Superimposing an AC voltage of 3.54 Vrms with a DC source of 10 V results in a waveform that: A) peaks at 20 V. B) peaks at 15 V. C) peaks at 13.54 V. D) both B and C
42)
43) A sine wave's instantaneous voltage is 0 V at A) 180 B) 360
43)
degrees. C) 0
D) all of these
44) The value of a AC sine wave at any instant can be represented by: A) a graph of the voltage or current vs. the angular measurement. B) the formula Vi = Vp × sin 0. C) a phasor whose angle and magnitude are representative of the AC signal. D) all of these.
44)
Figure 8- 2 45) Find PR1 in Figure 8-2. A) 97.8 mW
45) B) 0 W
C) 196 mW
D) 48.9 mW
46) A formula for VRMS is _ A) 2.8 × VP
. B) 0.707 × VP
C) 2 × VP
D) 0.707 × VPP
46)
47) In a two-resistor series circuit VR1 = 6.5 VRMS and VR2 = 3.2 VRMS. The source voltage is . A) 9.19 VP B) 9.7 VP C) 4.53 VP D) 13.7 VP
8
47)
Figure 8- 2 48) Calculate VR1 in Figure 8-2. A) 6.84 VP B) 13.7 VP
48) C) 13.2 VP
D) 21.4 VP
49) The time required by a 10 V square wave to change from 1 V to 9 V is known as the . A) period B) rise time C) pulse width D) fall time
49)
50) The output impedance of a function generator is usually A) 50 ▲ B) 600 ▲ C) 75 ▲ D) any of the above
50)
51) An oscilloscope's seconds/division switch is set on 20 µs/cm. If the trace is 7.5 cm long, what is the period? A) 5 µs B) 0.0015 s C) 1.5 µs D) 150 µs
51)
52) The AC sine wave varies from zero to its maximum value in accordance with: A) a geometric progression. B) a trigonometric relationship. C) an algebraic function. D) a mathematical formula.
52)
53) If the period of a square wave is 22 ms, what is its frequency? A) 22 Hz B) 45.5 Hz C) 45.5 kHz
53) D) 22 kHz
54) What is the instantaneous voltage at 284° on a 22 VPP sine wave? A) -2.66 V B) 0.33 V C) 10.7 V
D) -10.7 V
54)
55) If a rectangular wave's pulse width is 50 µS and its frequency is 4 kHz, its duty cycle is A) 80% B) 98.75% C) 1.25% D) 20%
9
.
55)
Figure 8- 1 56) In Figure 8-1, if the time from point A to H is 60 µs the frequency is A) 16.7 kHz B) 25 kHz C) 50 kHz D) More information is required to calculate the frequency.
.
56)
Figure 8- 2 57) If you measure about 56 VPP across the source in Figure 8-2, what is the trouble?
57)
A) R2 is open. B) R1 is open. C) Both R1 and R2 are open. D) There is no trouble. 56 VPP is a normal measurement for the source voltage. E) any of these 58) What is the approximate instantaneous voltage at 37° on a 169 VP sine wave? A) 239 V B) 102 V C) 119 V
58) D) 135 V
Figure 8- 2 59) If R1 shorts in Figure 8-2, VR2 A) decreases
.
59)
B) remains the same
10
C) increases
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 60) Commercial line voltages are usually square waves at a frequency of 60 Hz.
60)
61) A sine wave's frequency equals the reciprocal of its period.
61)
62) RMS is another name for peak.
62)
63) Single-phase power cannot be converted to three-phase power.
63)
64) One complete sine wave contains 360°.
64)
65) The term RMS stands for "root-mean-square."
65)
66) A sine wave's peak value is smaller than its RMS value.
66)
67) Only frequency increases with the speed of an AC generator.
67)
68) An ac current is inversely proportional to an ac voltage.
68)
69) 7.07 VPP is approximately equal to 2.5 VRMS.
69)
70) Rise time, fall time, and duty cycle are all terms associated with sine wave measurement.
70)
71) Kirchhoff's voltage law can be used with resistive ac circuits.
71)
72) 20 Vrms of alternating current will illuminate a given lamp at the same intensity as 20 V of direct current.
72)
73) Current flows both ways simultaneously in an AC circuit.
73)
74) The higher a sine wave's frequency, the shorter its period.
74)
75) The period of a 5 Hz wave form is 200 ms.
75)
11
Answer Key Testname: CH 8
1) D 2) D 3) B 4) B 5) A 6) A 7) D 8) C 9) C 10) D 11) C 12) A 13) C 14) A 15) B 16) D 17) B 18) D 19) A 20) B 21) B 22) C 23) A 24) C 25) C 26) B 27) A 28) D 29) A 30) D 31) D 32) A 33) A 34) A 35) C 36) B 37) A 38) D 39) D 40) B 41) D 42) B 43) D 44) D 45) D 46) B 47) D 48) D 49) B 50) D 12
Answer Key Testname: CH 8
51) D 52) B 53) B 54) D 55) D 56) A 57) E 58) B 59) C 60) FALSE 61) TRUE 62) FALSE 63) FALSE 64) TRUE 65) TRUE 66) FALSE 67) FALSE 68) FALSE 69) TRUE 70) FALSE 71) TRUE 72) TRUE 73) FALSE 74) TRUE 75) TRUE
13
Chapter 9: Capacitors MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) If the frequency applied to a capacitor increases, the capacitive reactance A) increases B) decreases C) varies up and down D) remains the same 2) What is the capacitance that stores 1.175 µC of charge and drops 25 V? A) 0.047 µF B) 47 µF C) 4.7 µF
.
1)
2) D) 0.47 µF
3) Reactive power (Pr) in a capacitor is defined as the rate at which a capacitor stores or returns energy and is measured in: A) watts reactive. B) volts per time constant. C) current per time constant. D) volt-ampere reactive.
3)
4) How long will it take for a 22 µF capacitor to completely discharge through a 4.7 k▲ resistor? A) 0.827 s B) 0.207 s C) 0.103 s D) 0.517 s
4)
5) If an uncharged capacitor, a resistor, a switch and a 12 V battery are connected in series, what is the voltage across the capacitor at the instant the switch is closed? A) 12 V B) 24 V C) 0 V D) 6 V
5)
6) A 65 Vrms signal is applied to a 10 F capacitor. What is the total peak current? A) 6.5 A B) 153 mA C) 6.5 kA D) not enough information
6)
7) In a transistor amplifier the input ac signal and the output of the amplifier must be connected in a way that not does affect the dc bias voltage. This is accomplished by using a(n) _ _ capacitor. A) isolation B) small value C) large value D) coupling
7)
8) How long will it take to completely charge a 0.047 µF capacitor through a 1 M▲ resistor? A) 0.047 s B) 0.235 s C) 0.029 s D) 0.47 s
8)
9) If a 22 µF capacitor is connected to a 15 V 400 Hz source, its current equals A) 55 mA B) 1.81 A C) 829 mA
9)
. D) 18.1 mA
10) There is often a capacitor connected to ground between the bridge rectifier and the voltage regulator in a power supply. In order to limit surge current a _ is inserted between the bridge and the regulator. A) series capacitor B) surge capacitor C) surge resistor D) a shunt inductor
1
10)
Figure 9- 1 11) What is CT in Figure 9-1? A) 70.1 µF
11) B) 25.2 µF
C) 82 µF
D) 8.78 µF
12) What is the small amount of power lost in a capacitive circuit due to the internal resistance of the capacitors? A) ideal power B) instantaneous power C) reactive power D) true power
12)
13) If a 47 µF capacitor is connected to a 20 V, 400 Hz source, the current is A) 2.36 A B) 8.51 A C) 0.851 A
13)
. D) 425 A
14) When capacitors are connected in parallel, their total capacitance act like: A) resistance connected in parallel. B) resistance connected in series-parallel. C) resistance connected in series. D) all of these.
14)
15) If a 4.7 µF capacitor and a 10 k▲ resistor are connected in series across 25 VDC, approximately how much voltage will the resistor drop after charging for just one time constant? A) 15.8 V B) 9.20 V C) 21.6 V D) 23.8 V
15)
16) The time constant for a capacitor for each time period is: A) 37% of the decrease in value. B) a constant factor. C) 63% of the increase in value. D) all of these.
16)
17) If a 0.1 µF capacitor and a 2.2 k▲ resistor are connected in series across 30 VDC, how much voltage will the capacitor drop after charging for just one time constant? A) 19.0 V B) 29.4 V C) 28.5 V D) 25.9 V
17)
18) What is one time constant of a 47 µF capacitor in series with a 120 k▲ resistor? A) 54.6 s B) 5.64 s C) 0.564 ms
18) D) 564 ms
19) Electrolytic capacitors must be connected into a circuit such that: A) reversal of polarity does not happen. B) voltage rating marked is not exceeded. C) positive lead to positive voltage; negative lead to negative voltage. D) all of these. 20) If a 1 µF, 2.2 µF and 0.05 µF capacitor are connected in series, CT is less than A) 1 µF B) 0.05 µF C) 2.2 µF
2
19)
. D) 0.001 µF
20)
21) If a 0.047 µF capacitor operates at 220 kHz, XC equals . A) 15.4 ▲ B) 154 ▲ C) 15.4 k▲
21) D) 1.54 k▲
22) A test instrument designed to be used for the testing of capacitors is the A) digital multimeter B) LCR Meter C) analog multimeter D) oscilloscope
.
23) What is one time constant of a 4.7 µF capacitor in series with a 22 k▲ resistor? A) 103 ms B) 1.03 ms C) 0.103 ms
D) 10.3 ms
24) If a 4.7 µF capacitor operates at 10 kHz, XC equals A) 3.39 ▲ B) 339 ▲
D) infinite ▲
. C) 294 µ▲
22)
23)
24)
25) A capacitor that transfers an ac signal from one stage to another is called a A) filter B) bypass C) transfer
capacitor. D) coupling
25)
26) How long will it take a 1 µF capacitor to completely discharge through a 47 k▲ resistor? A) 235 ms B) 47 ms C) 235 s D) 47 s
26)
27) The time constant of a capacitor is: A) directly proportional to the capacitance in the circuit. B) the time required to charge to 63% or discharge to 37%. C) directly proportional to the resistance in the circuit. D) all of these.
27)
28) How much voltage is dropped across a 150 µF capacitor after 3.33 seconds if it is charged by a 50 V source through a 22 K▲ resistor? A) 47.5 V B) 31.8 V C) 49 V D) 43.3 V
28)
29) If an uncharged capacitor, a resistor, a switch and a 12 V battery are connected in series, what is the voltage across the capacitor after it is fully charged?
29)
A) 24 V
C) -6 V
B) 12 V
D) 6 V
30) How much charge is stored in a 0.022 µF capacitor that drops 22 V? A) 0.484 µC B) 48.4 µC C) 4.84 µC
30) D) 0.0484 µC
31) If a 0.05 µF and 0.1 µF capacitor are connected in parallel across a 20 V source, the total capacitance equals _ and each capacitor drops . A) 0.10 µF, 20 V B) 0.15 µF, 10 V C) 0.15 µF, 20 V D) 0.05 µF, 15 V
31)
32) If four 0.022 µF capacitors are connected in parallel, CT equals A) 0.049 µF B) 0.088 µF C) 0.044 µF
32)
.
33) If the dc working voltage of a capacitor is 100 V, the dielectric must withstand A) 85 VRMS B) 220 VPP C) 100 VDC
D) 0.022 µF . D) 75 VRMS
34) What is the capacitance of a capacitor that drops 50 V and stores 0.500 µC of charge? A) 0.1 µF B) 0.001 µF C) 1 µF D) 0.01 µF
3
33)
34)
35) If a 0.1 µF, 0.1 µF and 0.05 µF capacitor are connected in series across a 75 V source, the voltage drop across the smallest capacitor equals . A) 50 V B) 37.5 V C) 18.8 V D) 100 V
35)
36) How much charge is stored in a 0.47 µF capacitor that drops 18 V? A) 846 µC B) 8.46 µC C) 84.6 µC
36) D) 0.846 µC
37) A commonplace use for capacitors in electronics is to: A) block DC voltages. B) block AC voltages. C) pass DC voltages only. D) pass both AC and DC voltages.
37)
38) When capacitors are connected in series, their total capacitance act like: A) resistance connected in series-parallel. B) resistance connected in parallel. C) resistance connected in series. D) all of these.
38)
39) A common use for electrolytic capacitors found in power supplies is _ A) blocking DC B) passing AC C) filtering
39)
. D) decoupling
40) Electrolytic capacitors differ from many other capacitors in construction in that they are: A) polarized. B) larger. C) smaller. D) sensitized.
40)
41) Upon checking the voltage output of a power supply with an oscilloscope, you notice an unusually large amount of ripple. What could possibly be the problem? A) shorted filter capacitor B) shorted load C) open filter capacitor D) either B or C
41)
42) If a 0.022 µF, 0.022 µF and 0.05 µF capacitor are connected in series across a 25 V source, the voltage drop across the largest capacitor equals . A) 10.2 V B) 11.8 V C) 17.5 V D) 4.51 V
42)
43) The removal of high frequency transient voltages with a capacitor is called: A) bypassing. B) decoupling. C) coupling.
43) D) ac blocking.
44) What is the minimum dc working voltage rating for a capacitor that must drop 120 VRMS? A) 170 V B) 339 V C) 84.8 V D) 120 V
44)
45) If a 1 µF capacitor and a 10 k▲ resistor are connected in series across 20 VDC, approximately how much voltage will the capacitor drop after charging for just one time constant? A) 17 V B) 11.0 V C) 12.6 V D) 12.1 V
45)
46) In a capacitive AC circuit, the phase relationship between the voltage and the current is such that the: A) voltage is leading the current. B) current is leading the voltage. C) current is 180 degrees out of phase with voltage. D) voltage is 360 degrees out of phase with current.
46)
4
47) If a 22 µF and 100 µF capacitor are connected in parallel across a 15 V source, the total capacitance equals _ and the 22 µF capacitor drops . A) 122 µF, 15 V B) 18 µF, 15 V C) 18 µF, 5.2 V D) 1220 µF, 30 V
47)
48) How long will it take for a 22 µF capacitor to completely charge through a 47 k▲ resistor? A) 5.17 s B) 2.068 s C) 8.272 s D) 1.034 s
48)
49) If a 0.047 µF, 0.047 µF and 0.47 µF capacitor are connected in series across a 25 V source, the total capacitance equals _ and each 0.047 µF capacitor drops . A) 0.022 µF, 25 V B) 0.564 µF, 1.2 V C) 0.564 µF, 11.9 V D) 0.022 µF, 11.9 V
49)
50) When connecting a large electrolytic capacitor to a circuit with a 100 VDC source, place the negative end of the capacitor . A) in either position; the polarity is not important B) towards the positive side of the source C) towards the negative side of the source
50)
51) If an uncharged capacitor, a resistor, a switch and a 12 V battery are connected in series, at approximately what time will the capacitor reach full charge? A) 12 × R × C B) R × C C) 5 × R × C D) The time cannot be predicted.
51)
52) At what frequency is a 0.001 µF capacitor operating if its reactance is 45 k▲? A) 354 kHz B) 3.54 kHz C) 3.54 MHz
52)
53) At what frequency is a 2000 pF capacitor operating if its reactance is 745 ▲? A) 1010 Hz B) 1.01 kHz C) 107 kHz
D) 35.4 kHz 53) D) 10.1 kHz
54) With three capacitors in series, the current lags the voltage by: A) 90 degrees. B) 45 degrees. C) 30 degrees. D) none of the above.
54)
55) How long will it take a 0.047 µF capacitor to fully charge through a 100 k▲ resistor? A) 2.35 s B) 0.235 ms C) 235 ms D) 23.5 ms
55)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 56) When two capacitors are connected in series across a dc source, the smallest capacitor drops the largest voltage.
56)
57) A capacitor can fully charge in one time constant.
57)
58) If the distance between the plates of a capacitor increases, the capacitance decreases.
58)
59) Capacitance is a capacitor's ability to store resistance.
59)
60) To find the total capacitance of two capacitors in parallel, you must combine them using a similar procedure as resistors in parallel.
60)
5
61) The voltage rating of a capacitor indicates the voltage it will charge up to.
61)
62) Efficient filtering is directly related to RC time constant.
62)
63) A capacitor blocks dc and passes ac.
63)
64) Electrolytic capacitors are ideal for alternating current applications.
64)
65) If the plate area of a capacitor decreases, the capacitance decreases.
65)
66) Capacitance is the ability to store voltage.
66)
67) Leakage through a capacitor is undesirable.
67)
68) A capacitor will fully charge in about five time constants.
68)
69) When two capacitors are connected in parallel across a dc source, the smaller capacitor drops the larger voltage.
69)
6
Answer Key Testname: CH 9
1) B 2) A 3) D 4) D 5) C 6) D 7) D 8) B 9) C 10) C 11) D 12) D 13) A 14) C 15) B 16) B 17) A 18) B 19) D 20) B 21) A 22) B 23) A 24) A 25) D 26) A 27) D 28) B 29) B 30) A 31) C 32) B 33) C 34) D 35) B 36) B 37) A 38) B 39) C 40) A 41) D 42) D 43) B 44) A 45) C 46) B 47) A 48) A 49) D 50) C 7
Answer Key Testname: CH 9
51) C 52) B 53) C 54) D 55) D 56) TRUE 57) FALSE 58) TRUE 59) FALSE 60) FALSE 61) FALSE 62) TRUE 63) TRUE 64) FALSE 65) TRUE 66) FALSE 67) TRUE 68) TRUE 69) FALSE
8
Chapter 10: RC MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Figure 10- 1 1) If the operating frequency increases in Figure 10-1, how does the current change? A) It remains the same. B) It decreases. C) It decreases to zero. D) It increases.
1)
Figure 10- 3 2) If the resistance is reduced to 4 k▲ in Figure 10-3, the cutoff frequency equals A) 99 Hz B) 995 Hz C) 480 Hz
. D) 6250 Hz
3) What is the cutoff frequency in Figure 10-3? A) 85 Hz B) 1012 Hz
D) 118 Hz
2)
3) C) 995 Hz
Figure 10- 1 4) If the frequency is 400 Hz in Figure 10-1, what is the value of capacitance? A) 10 µF B) 8.8 µF C) 6.6 µF
1
4) D) 3.3 µF
5) If the operating frequency decreases in Figure 10-1, how does the resistance value change? A) It increases. B) It remains the same. C) It opens. D) It decreases.
5)
Figure 10- 2 6) How much voltage does the resistor drop in Figure 10-2? A) 10 V B) 19.94 V C) 20 V
6) D) 59 mV
7) If the resistor value increases in Figure 10-2, then how does the total current change? A) It remains the same. B) It decreases to zero. C) It decreases. D) It increases.
7)
8) Simple RC circuits can be viewed as what type of filter? A) low pass B) active C) high pass
8) D) passive
Figure 10- 1 9) What is the circuit's impedance in Figure 10-1? A) 280 ▲ B) 120 ▲
9) C) 520 ▲
D) 418 ▲
Figure 10- 3 10) If the circuit in Figure 10-3 has an output voltage that's too high at the cutoff frequency, A) the resistor has shorted B) the resistor has opened C) the capacitor has shorted D) the capacitor has become leaky
2
.
10)
Figure 10- 4 11) This frequency response curve in Figure 10-4 represents what type of filter? A) band stop B) low pass C) high pass
11) D) band pass
Figure 10- 1 12) If the frequency equals 60 Hz in Figure 10-1, what is the value of capacitance? A) 44 µF B) 22 µF C) 88 µF
12) D) 66 µF
Figure 10- 2 13) What change would decrease the power factor in Figure 10-2? A) decreasing the value of the capacitor B) increasing the value of the capacitor C) increasing the value of the resistor D) increasing the value of Vs
3
13)
14) It has been determined that the phase shift of a given parallel RC circuit is lower than predicted. Which of the following most likely has caused this? A) The capacitance has decreased. B) The function generator frequency control has been accidentally moved to a lower frequency. C) Resistance has decreased. D) could be A or C
14)
15) In a series RC circuit, as the phase angle between the applied voltage and the total current increases, this is the same as: A) power factor increasing. B) true power decreasing. C) power factor decreasing. D) apparent power decreasing.
15)
Figure 10- 3 16) If the resistor changes to 2.2 k▲ in Figure 10-3, the new cutoff frequency equals . 16) A) 1.81 kHz B) 1.01 kHz C) 995 Hz D) 1.18 kHz 17) An RC high pass filter takes its output across: A) the parallel capacitor. C) the series resistor.
17) B) the series capacitor. D) the parallel resistor.
18) The output voltage of an RC high pass filter at a designated frequency is low. What is a possible problem? A) open resistor B) function generator misadjusted C) shorted capacitor D) not enough information
18)
Figure 10- 1 19) If the operating frequency decreases in Figure 10-1, how does the current change? A) It increases. B) It decreases. C) It decreases to zero. D) It remains the same.
4
19)
20) If the operating frequency decreases in Figure 10-1, how does the capacitance value change? A) It increases. B) It decreases to zero. C) It remains the same. D) It decreases.
20)
21) An RC lag network is similar to a: A) low pass filter. C) stop pass filter.
21) B) high pass filter. D) band pass filter.
Figure 10- 3 22) If the input voltage increases to 50 V in Figure 10-3, what is the output voltage at the cutoff frequency? A) 17.7 V B) 8.84 V C) 70.7 V D) 35.4 V
22)
23) Which of these troubleshooting procedures should be performed first? A) Analyze the problem and decide where best to start. B) Take random measurements around point of failure. C) Check test equipment connections. D) Slap the device firmly to dislodge foreign objects.
23)
24) In an RC circuit, the capacitive reactance is: A) inversely proportional to the frequency. C) inversely proportional to the capacitance.
24) B) decreases as the frequency increases. D) all of these.
25) If the bandwidth of a low-pass filter is 0 to 1 kHz, the cutoff frequency is A) 2 kHz B) 1 kHz C) 0 Hz
. D) 500 Hz
25)
Figure 10- 1 26) If the operating frequency increases in Figure 10-1, how does the phase angle change? A) It increases. B) It decreases. C) It remains the name. D) It changes to another quadrant.
5
26)
27) If there is 1 ARMS through the resistor and 1 ARMS through the capacitor in a parallel RC circuit, then the total current equals _. A) 2 ARMS B) 2.28 ARMS C) 1.41 ARMS D) 1 ARMS
27)
Figure 10- 1 28) If the frequency increases in Figure 10-1, the phase angle _ and the impedance A) decreases, increases B) increases, increases C) increases, decreases D) decreases, decreases 29) If the resistor changes to 2.2 k▲ in Figure 10-1, how does the total current change? A) It remains the same. B) It increases. C) It decreases to zero. D) It decreases.
_.
28)
29)
Figure 10- 3 30) What is the output voltage at the cutoff frequency in Figure 10-3? A) 15.6 V B) 22 V C) 31.1 V
30) D) 6.45 V
Figure 10- 1 31) What is the true power in Figure 10-1? A) 5.73 W B) 916 mW
31) C) 275 mW
6
D) 5.73 mW
32) Power in an RC circuit can be measured as: A) true power (Ptrue). C) reactive power (Pr).
32) B) apparent power (Pa). D) all of these.
Figure 10- 1 33) Calculate the apparent power in Figure 10-1. A) 14.37 VA B) 5.66 VA
33) C) 1.70 VA
D) 5.99 VA
Figure 10- 2 34) What change would increase the power factor in Figure 10-2? A) Increasing the value of the capacitor B) Increasing the value of the resistor C) Increasing the value of the source voltage D) Decreasing the value of the capacitor
34)
35) In an RC filter circuit, the cutoff frequency is defined as the frequency at which: A) the output voltage drops to 70% of maximum. B) the output voltage drops to 33% of maximum. C) the output voltage is cutoff, with minimum or zero output. D) the output voltage drops to 66% of maximum.
35)
Figure 10- 1 36) Calculate the voltage drop across the capacitor in Figure 10-1. A) 4.82 V B) 3.69 V C) 14.4 V
7
36) D) 11.5 V
Figure 10- 3 37) If the resistor is changed to 100 k▲ in Figure 10-3, what is the new cutoff frequency? A) 79.6 Hz B) 318 Hz C) 159 Hz D) 39.8 Hz
37)
38) When an AC voltage is supplied to an RC circuit, the AC's current and amplitude will be: A) leading the voltage. B) varying in the same manner. C) similar in waveform. D) all of these.
38)
Figure 10- 1 39) If the operating frequency increases in Figure 10-1, how does the resistor value change? A) It decreases. B) It opens. C) It remains the same. D) It increases.
39)
Figure 10- 2 40) Which statement describes the relationship of IC and IR in Figure 10-2? A) They are in phase. B) They are 180° out of phase. C) IC leads IR.
40)
D) IC lags IR.
41) A power factor of 1 indicates that the circuit phase angle is A) 90° B) 180° C) 0°
.
41) D) 45°
42) If the true power is 100 W and the reactive power is 100 VAR, the apparent power is A) 141 VA B) 100 VA C) 141 W D) 200 VA
8
.
42)
Figure 10- 3 43) The circuit in Figure 10-3 is known as a A) low-pass filter C) band-pass filter
.
43) B) parallel RC circuit D) high-pass filter
Figure 10- 2 44) How much voltage does the capacitor drop in Figure 10-2? A) 10 V B) 59 mV C) 20 V
44) D) 19.94 V
Figure 10- 3 45) What is the circuit fault in Figure 10-3 if the output voltage equals 0 V at the cutoff frequency? A) The capacitor has shorted. B) The capacitor has opened. C) The resistor has shorted. D) The capacitor has become leaky.
9
45)
Figure 10- 1 46) If the source voltage is changed to 100 V in Figure 10-1, find the true power. A) 22.9 mW B) 11 W C) 22.9 W
46) D) 3.66 W
47) If the frequency decreases in Figure 10-1, the phase angle _ and the impedance A) decreases, decreases B) increases, decreases C) increases, increases D) decreases, increases
_.
47)
48) If the operating frequency decreases in Figure 10-1, how does the phase angle change? A) It changes to another quadrant. B) It decreases. C) It remains the same. D) It increases.
48)
49) If there is 10 VRMS across the resistor and 10 VRMS across the capacitor in a series RC circuit, then the source voltage equals . A) 10 VRMS B) 28.3 VRMS C) 14.1 VRMS D) 20 VRMS
49)
Figure 10- 2 50) Calculate the total impedance in Figure 10-2. A) 880 ▲ B) 1000 ▲
50) C) 258 ▲
51) In a X10 oscilloscope probe input resistance is _ factor of 10. A) increased, increased C) decreased, decreased
D) 62 ▲
and input capacitance is _ B) decreased, increased D) increased, decreased
10
by a
51)
Figure 10- 3 52) If the output were taken across the resistor in Figure 10-3, the circuit would be known as a . A) band-notch filter B) band-pass filter C) low-pass filter D) high-pass filter
52)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 53) A VA rating is more relevant when judging the current delivery capacity for a given signal source.
53)
54) The phase angle of an RC circuit varies inversely with frequency.
54)
55) The phasor combination of VR and VC in an RC series circuit equals the source voltage.
55)
56) The phasor combination of XC and R is called Z.
56)
57) Power factor values close to 0 denotes an RC circuit with mostly true power.
57)
58) A high pass filter will cause some phase shifting of the signal.
58)
59) The total current in an RC circuit always leads the source voltage.
59)
60) A leaky capacitor can be equated as a capacitor with a resistor being placed in series with it.
60)
61) When the frequency applied to an RC circuit varies, the value of XC varies.
61)
62) As the frequency applied to an RC circuit is decreased, the phase angle decreases.
62)
63) As the frequency applied to an RC circuit increases, the impedance decreases.
63)
64) As the frequency applied to an RC circuit varies, both XC and resistance vary.
64)
65) The total current in an RC circuit always lags the source voltage.
65)
66) An RC circuit can be used as a filter to eliminate selected frequencies.
66)
11
Answer Key Testname: CH 10
1) D 2) B 3) A 4) D 5) B 6) C 7) C 8) D 9) D 10) D 11) C 12) B 13) B 14) D 15) C 16) A 17) C 18) B 19) B 20) C 21) A 22) D 23) A 24) D 25) B 26) B 27) C 28) D 29) D 30) A 31) A 32) D 33) D 34) D 35) A 36) C 37) D 38) D 39) C 40) C 41) C 42) A 43) A 44) C 45) A 46) C 47) C 48) D 49) C 50) C 12
Answer Key Testname: CH 10
51) D 52) D 53) TRUE 54) TRUE 55) TRUE 56) TRUE 57) FALSE 58) TRUE 59) TRUE 60) FALSE 61) TRUE 62) FALSE 63) TRUE 64) FALSE 65) FALSE 66) TRUE
13
Cahpter 11 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Inductors . A) have a high resistance to direct current C) block direct current
1) B) pass direct current D) have high reactance to direct current
2) Determination of an inductor's value can be had by what method(s)? A) Connect the inductor in series with a known value of resistance, apply a square wave of a known voltage value, then use the time constant formula. B) Use an inductance meter. C) Apply a signal of a known frequency and voltage, then use Ohm's law and the inductive reactance formula. D) any of the above
2)
3) What is the time constant for a 50 mH inductor and 5 k▲ resistor connected in series? A) 250 s B) 100 s C) 10 ms D) 10 µs
3)
4) If an inductor, resistor and switch are connected in series to a 12 V battery, what is the magnitude of the inductor's voltage at the instant that the switch is closed? A) 6 V B) 0 V C) 12 V D) 4 V
4)
5) It has been determined that the source of audible noise for a radio is due to the power supply voltage. How can an inductor be configured to eliminate this noise? A) Connect the inductor in parallel with the radio. B) Connect the inductor in series with the radio power wire. C) An inductor will not affect the noise. D) both B and C
5)
6) Which type of inductor core material is likely to produce the least inductance? A) ferrite B) air C) iron
6)
7) In an inductive AC circuit, the phase relationship between the voltage and the current is such that the: A) current is 180 degrees out of phase with voltage. B) voltage is 360 degrees out of phase with voltage. C) current is lagging the voltage. D) voltage is lagging the current.
7)
8) What is the total inductance of a 40 mH inductor and a 24 mH inductor connected in parallel? A) 15 mH B) 32 mH C) 64 mH D) 150 mH
8)
9) An 0.05 µH inductance is larger than a A) 0.00005 H inductance C) 0.000005 H inductance
9)
. B) 0.0000005 H inductance D) 0.000000008 H inductance
1
10) The most commonplace use for inductors in electronics: A) blocks AC voltages. B) blocks DC voltages. C) passes AC voltages. D) passes DC voltages. 11) If an inductor has an ac current flowing through it, the magnetic field is _ A) moving from south to north B) constantly changing C) steady D) collapsed 12) A 0.33 mH inductance is smaller than a A) 33 pH inductance C) 0.0005 H inductance
10)
.
.
11)
12) B) 330 pH inductance D) 0.05 mH inductance
13) What is the inductive reactance of a 0.2 mH inductor operating at 1 kHz? A) 126 ▲ B) 1.26 ▲ C) 126 k▲ 14) If a 15 µH inductor has a 2.2 K▲ reactance, the frequency equals A) 4.28 kHz B) 4.28 MHz C) 23.3 MHz
13) D) 1.26 k▲ .
14) D) 23.3 kHz
15) The time constant of an inductor is: A) inversely proportional to the resistance in the circuit. B) directly proportional to the inductance in the circuit. C) the time required for voltage or current to increase to 63% or to decrease to 37%. D) all of these.
15)
16) If two inductors are connected in a series AC circuit, which inductor drops more voltage? A) the smaller inductance B) It depends upon the source voltage. C) the larger inductance D) It depends upon the frequency.
16)
17) Reactive power (Pr) in an inductor is defined as the rate at which an inductor stores or returns energy and is measured in: A) watts reactive. B) volt-ampere reactive. C) current per time constant. D) volts per time constant.
17)
18) How many time constants will it take to completely build a magnetic field around an inductor? A) 1 B) 2 C) 3 D) 4 E) 5
18)
19) What is the total inductance if a 50 mH inductor is connected in series with a 15 mH inductor? A) 65 mH B) 15 mH C) 11.5 mH D) 50 mH
19)
20) In a switch-mode power supply the role of the inductor is A) surge protection B) to function as a low-pass filter C) to produce a constant load current D) to function as a high-pass filter
20)
21) If an inductor carries 100 mADC of current when connected across a 30 VDC source, then what is its resistance? A) 60 ▲ B) 0 ▲ C) 300 ▲ D) 30 ▲
21)
2
22) What is the maximum current in a 12 mH inductor if it is connected in series with a 10 k▲ resistor and a 15 VDC source? A) 1.2 mA B) 6.32 mA C) 2.2 mA D) 1.5 mA
22)
23) What is the inductance of a 20 mH inductor connected in parallel with a 50 mH inductor? A) 20 mH B) 50 mH C) 14.3 mH D) 70 mH
23)
24) If a 50 mH inductor is in series with a 50 k▲ resistor across a 50 VDC source, what is the maximum current that will flow in the circuit? A) 1 µA B) 1 mA C) 10 mA D) 100 µA
24)
25) What is the inductive reactance of a 150 mH inductor operating at 10 kHz? A) 1500 ▲ B) 8450 ▲ C) 6280 ▲
25) D) 9420 ▲
Figure 11- 1 26) How much current flows in the circuit in Figure 11-1 if connected to a 12 VPP, 2 kHz source? A) 126 mAp-p B) 10.1 mAp-p C) 4.77 mAp-p D) 60.5 mAp-p
26)
27) The ripple voltage as measured at the output of a power supply has increased. Which of the following could be the problem? A) partial shorting of the windings of the filtering coil B) load resistance has dropped C) resistance of the coil has decreased D) either A or B
27)
28) What is the inductive reactance of an inductor that drops 12 VRMS and carries 50 mARMS? A) 60 ▲ B) 6 ▲ C) 600 ▲ D) 240 ▲
28)
29) In an inductive circuit, the A) current, voltage C) voltage, reactance
29)
lags the
. B) current, resistance D) voltage, resistance
30) An inductor can be simulated using resistors, capacitors, and operational amplifiers. Ths circuit is called a . A) modulator B) oscillator C) inducer D) gyrator
3
30)
31) If a 1 mH, 3.3 mH, and 0.1 mH inductor are connected in parallel, LT equals A) less than 0.1 mH B) greater than 3.3 mH C) 4.4 mH D) 5.3 mH 32) Connecting a inductor in A) 233 mH, series C) 233 mH, parallel
.
with a 70 mH inductor produces a 100 mH inductance. B) 30 mH, parallel D) 30 mH, series
31)
32)
Figure 11- 1 33) What is the total inductance in Figure 11-1? A) 15.8 mH B) 12.7 mH
33) C) 225 mH
D) 95 mH
34) What is the reactance of a 100 µH inductor operating at 100 kHz? A) 62.8 k▲ B) 6.28 ▲ C) 62.8 ▲
34) D) infinite ▲
35) When inductors are connected in parallel, their total inductance acts like: A) resistance connected in parallel. B) resistance connected in series. C) resistance connected in series-parallel. D) all of these.
35)
36) What is the total inductance of a 25 mH inductor connected in parallel with a 100 mH inductor? A) more than 125 mH B) less than 20 mH C) 125 mH D) 20 mH
36)
37) If a 27 m H inductor has a reactance of 5.5 k▲, the frequency equals A) 32.4 kHz B) 932 Hz C) 324 Hz
37)
38) What is the total inductance of four 10 mH inductors connected in series? A) 250 mH B) 2.5 mH C) 40 mH
. D) 3.24 kHz
38) D) 40,000 µH
39) The quality factor of a coil or inductor is calculated by: 1 A) QL = B) QL = 2L fL. 2 L fL C) QL = 2L fL/RW.
D) QL =
L R
40) If a 25 mH inductor drops 50 V while operating at 400 Hz, what is XL? A) 62.8 k▲ B) 62.8 ▲ C) 6.28 k▲
4
39)
40) D) 628 ▲
41) What is one time constant for a 10 mH inductor connected in series with a 47 k▲ resistor? A) 470 S B) 213 µS C) 470 mS D) 0.213 µS
41)
42) What is the reactance of an inductor that carries 1.25 mAP and drops 25 VP at 100 Hz? A) 15.7 k▲ B) 31.3 ▲ C) 20 k▲ D) 3.13 k▲
42)
43) If an inductor carries 150 mADC of current when connected across a 65 VDC source, what is its resistance? A) 433 ▲ B) 65 ▲ C) 30 ▲ D) 26.7 ▲
43)
44) If two 2.5 mH inductors are connected in series with a 4.7 k▲ resistor and the source voltage is 100 VDC, what is the circuit's maximum current? A) 7.9 mA B) 63.2 mA C) 21.3 mA D) 1.1 mA
44)
45) Do iron-core inductors or air-core inductors generally have the larger inductance? A) neither; iron-core inductors and air-core inductors have the same inductance B) iron core C) air core D) There is no way to tell.
45)
46) The time constant for an inductor for each time period: A) corresponds to a 37% of the decrease in value. B) corresponds to a 63% of the increase in value. C) is a constant value. D) all of these.
46)
47) What is the total inductance of a 14 mH, 22 mH and 45 mH inductor connected in series? A) 81 µH B) 81 mH C) 7.2 mH D) 20 mH
47)
48) When inductors are connected in series, their total inductance acts like: A) resistance connected in parallel. B) resistance connected in series-parallel. C) resistance connected in series. D) all of these.
48)
49) If a 50 mH inductor operates at 22 kHz, XL equals A) 1100 ▲ B) 6912 ▲
49)
50) Connecting a inductor in inductance. A) 186 mH, series C) 186 mH, parallel
. C) 500 ▲
D) 113 ▲
with a 100 m H inductor produces a 65 m H
50)
B) 35 mH, series D) 35 mH, parallel
51) How many time constants will it take to completely collapse an inductor's magnetic field? A) 4 B) 3 C) 5 D) 1
51)
52) Stray capacitance for a coil becomes a problem: A) at resonant frequencies. C) with ac circuits.
52) B) with high frequencies. D) with low frequencies.
5
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 53) Inductors in series or parallel combine just like resistors in series or parallel.
53)
54) Inductors can radiate electromagnetic energy to other components in a system.
54)
55) The energy stored in an inductor's electromagnetic field is produced by the resistance of the inductor's winding.
55)
56) An iron-core inductor is used in low frequency applications.
56)
57) The energy stored in an inductor's electromagnetic field is produced by the inductor's current.
57)
58) True power for an inductor is measured in VAR rather than watts.
58)
59) The voltage and current are in phase in an inductive circuit.
59)
60) If an inductor is placed in an ac circuit, the ac voltage across the inductor leads the ac current through it.
60)
61) Inductive reactance decreases as frequency increases.
61)
62) An inductor passes direct current and opposes alternating current.
62)
63) When a DC voltage is first applied to an inductor, the initial circuit current is zero.
63)
64) An inductor is placed in series with the load for power supply filtering.
64)
65) The voltage leads the current in an inductive circuit.
65)
66) The total inductance of two parallel inductors equals the sum of their inductance values.
66)
67) The quality factor for an inductor becomes more apparent at higher frequencies.
67)
6
Answer Key Testname: CH 11
1) B 2) D 3) D 4) C 5) B 6) B 7) C 8) A 9) D 10) A 11) B 12) C 13) B 14) C 15) D 16) C 17) B 18) E 19) A 20) C 21) C 22) D 23) C 24) B 25) D 26) B 27) D 28) D 29) A 30) D 31) A 32) D 33) D 34) C 35) A 36) D 37) A 38) C 39) C 40) B 41) D 42) C 43) A 44) C 45) B 46) D 47) B 48) C 49) B 50) C 7
Answer Key Testname: CH 11
51) C 52) B 53) TRUE 54) TRUE 55) FALSE 56) TRUE 57) TRUE 58) FALSE 59) FALSE 60) TRUE 61) FALSE 62) TRUE 63) TRUE 64) TRUE 65) TRUE 66) FALSE 67) FALSE
8
Chapter 12: Inductors MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The voltage measured across the inductor in a series RL has dropped significantly from normal. What could possibly be the problem? A) The resistor has gone up in value. B) partial shorting of the windings of the inductor C) The resistor has gone down in value. D) either A or B
1)
2) An RL lag network is similar to a A) low pass filter. C) band pass filter.
2) B) stop pass filter. D) high pass filter.
Figure 12- 3 3) What is the cutoff frequency in Figure 12-3? A) 796 Hz B) 7.96 kHz
3) C) 637 Hz
D) 637 kHz
4) If a high-pass RL filter's cutoff frequency is 55 kHz, its bandwidth is theoretically . A) 110 kHz B) 0 kHz C) 55 kHz D) infinite
4)
Figure 12- 1 5) If the frequency increases in Figure 12-1, the phase angle _ and the impedance A) decreases, decreases B) decreases, increases C) increases, decreases D) increases, increases
1
_.
5)
6) If the frequency is 400 Hz in Figure 12-1, what is the inductance? A) 39.8 mH B) 39.8 H C) 25.12 H
6) D) 25.1 mH
Figure 12- 3 7) If some of the turns of the inductor in Figure 12-3 have shorted, how will the circuit change? A) The output voltage at the cutoff frequency will decrease. B) The cutoff frequency will increase. C) The output voltage at the cutoff frequency will increase. D) The cutoff frequency will decrease.
7)
Figure 12- 1 8) If the frequency decreases in Figure 12-1, the phase angle and the current _ A) increases, decreases B) increases, increases C) decreases, increases D) decreases, decreases 9) If the source voltage changes to 100 V in Figure 12-1, the true power is _ A) 16 W B) 40 W C) 40 mW
. D) 4 W
10) If the frequency is 60 Hz in Figure 12-1, what is the inductance? A) 26.5 mH B) 265 mH C) 3.77 mH
D) 3.77 H
11) What is the impedance in Figure 12-1? A) 1120 ▲ B) 104 ▲
D) 1040 ▲
.
8)
9)
10)
11) C) 112 ▲
12) In a series RL circuit, as the phase angle between the applied voltage and the total current increases, this is the same as: A) true power decreasing. B) power factor decreasing. C) apparent power decreasing. D) power factor increasing.
2
12)
13) If the true power is 10 W and the reactive power is 10 VAR, the apparent power is . A) 14.1 VA B) 5 VAT C) 100 VA D) 20 VA
13)
14) In a RL circuit, the inductive reactance is: A) directly proportional to the frequency. C) directly proportional to the inductance.
14) B) increases as the frequency increases. D) all of these.
15) Which of the following is typically most important of the three types of power in terms of work being done? A) apparent B) reactive C) inductive D) true
15)
Figure 12- 3 16) If the output is taken across the inductor in Figure 12-3, the circuit is known as a A) band-pass filter B) notch filter C) low-pass filter D) high-pass filter
_.
17) If the resistive current is 2 A and the inductive current is 2 A in a parallel RL circuit, total current is . A) 5.66 A B) 2.83 A C) 4 A D) 2 A
16)
17)
Figure 12- 1 18) If the operating frequency decreases in Figure 12-1, the phase angle _. A) remains the same B) increases C) decreases D) changes to another quadrant
18)
19) What is the voltage across the inductor in Figure 12-1? A) 44.6 V B) 0.894 V C) 0.4 V
19)
3
D) 4.47 V
20) A measured voltage of 0 V across the resistor in a parallel RL circuit would indicate: A) a blown fuse. B) an short in the inductor. C) an open in the resistor. D) either A or B.
20)
Figure 12- 1 21) If the frequency increases in Figure 12-1, the phase angle and the current _ A) decreases, decreases B) increases, increases C) decreases, increases D) increases, decreases 22) If a low-pass RL filter's cutoff frequency is 20 kHz, its bandwidth is A) 40 kHz B) 0 Hz C) 20 kHz
.
21)
.
22) D) unknown
Figure 12- 1 23) If the frequency decreases in Figure 12-1, the phase angle _ and the impedance A) increases, increases B) decreases, decreases C) increases, decreases D) decreases, increases 24) If VR is 10 V and VL is 10 V in a series RL circuit, the source voltage equals _ A) 10 V B) 28.3 V C) 20 V
_.
. D) 14.1 V
25) After troubleshooting a series RL circuit, you check the resistance of the inductor and it is around 40 ohms. What conclusion does this bring you to? A) Since the inductor's voltage was nearly zero, the inductor is probably okay, so the resistor must be open. B) Since the inductor's voltage was nearly zero, you are sure the windings have shorted. C) Since the inductor's voltage was nearly zero, the inductor is probably okay so the resistor must be shorted. D) not enough information
4
23)
24)
25)
Figure 12- 1 26) What is the apparent power in Figure 12-1? A) 0.8 VA B) 8.94 VA
26) C) 22.27 VA
D) 0.4 VA
Figure 12- 2 27) If the resistor decreases in Figure 12-2, the total current _ _. A) decreases to zero B) increases C) decreases D) remains the same
27)
28) Which statement describes the relationship of IL and IR in Figure 12-2? A) They are in phase. B) IL leads IR. C) They are 180° out of phase. D) IL lags IR.
28)
29) An RL high pass filter takes its output across: A) the parallel resistor. C) the series inductor.
29) B) the series resistor. D) the parallel inductor.
30) It is suspected that a high pass filter's cutoff frequency has changed. What pieces of test equipment could be used to check it out? A) an oscilloscope and a square wave generator B) voltmeter and a sine wave generator C) either A or B D) none of the above
5
30)
Figure 12- 3 31) What is the phase angle in Figure 12-3, at the cutoff frequency? A) 45.0° B) 49.9° C) 54.3°
31) D) 51.4°
Figure 12- 1 32) If the frequency increases in Figure 12-1, inductance _ _. A) decreases B) decreases to zero C) increases D) remains the same
32)
33) If a load is purely inductive and the reactive power is 10 VAR, the apparent power is A) 1.144 VA B) 14.14 VA C) 3.16 VA D) 10 VA 34) In an RL filter circuit, the cutoff frequency is defined as the frequency at which: A) the output voltage drops to 70% of maximum. B) the output voltage drops to 66% of maximum. C) the output voltage is cutoff, with minimum or zero output. D) the output voltage drops to 33% of maximum.
.
33)
34)
Figure 12- 1 35) Calculate the true power in Figure 12-1. A) 4 W B) 10 W
35) C) 1 W
6
D) 400 mW
36) In a basic crossover network, there will be a(n) in with the tweeter. A) inductor, parallel, capacitor, series C) capacitor, series, inductor, parallel
in
with the woofer and a(n)
36)
B) inductor, series, capacitor, series D) capacitor, series, inductor, series
Figure 12- 1 37) If the operating frequency decreases in Figure 12-1, the current _ _. A) increases B) decreases to zero C) decreases D) remains the same
37)
38) If the frequency increases in Figure 12-1, the phase angle _. A) changes to another quadrant B) remains the same C) decreases D) increases
38)
Figure 12- 2 39) What change would increase the power factor in Figure 12-2? A) increasing the source voltage B) decreasing the source voltage C) increasing the value of the resistor D) decreasing the value of the resistor
39)
Figure 12- 1 40) What is the phase angle in Figure 12-1? A) 54.3° B) 71.2°
40) C) 63.4°
7
D) 86.3°
Figure 12- 3 41) What effect will an open inductor have on the circuit in Figure 12-3? A) The output voltage at the cutoff frequency will increase. B) The current will drop to zero. C) The output voltage at the cutoff frequency will decrease. D) The cutoff frequency will increase.
41)
Figure 12- 2 42) What is the total impedance in Figure 12-2? A) 1.86 k▲ B) 1.07 k▲
42) C) 5.71 k▲
D) 9.09 k▲
43) If the resistance increases in Figure 12-2, the total current _ _. A) increases B) remains the same C) decreases to zero D) decreases
43)
44) The startup current for large induction motors is very high because A) the counter emf is very high B) the power factor is low C) the starting impedance is slightly capacitive D) the starting impedance is purely inductive
44)
8
Figure 12- 1 45) If the operating frequency decreases in Figure 12-1, the inductance . A) remains the same B) decreases C) increases D) decreases to zero 46) What is the cutoff frequency in Figure 12-1? A) 63 Hz B) 408 Hz
45)
46) C) 30 Hz
D) 25 Hz
47) When an ac voltage is supplied to an RL circuit, the ac's current and amplitude will be: A) varying in the same manner. B) similar in waveform. C) lagging the voltage. D) all of these.
47)
Figure 12- 3 48) The circuit in Figure 12-3 is known as a _ A) low-pass B) band-pass
filter. C) high-pass
49) What is VOUT at the cutoff frequency in Figure 12-3? A) 15.1 V B) 15.6 V C) 14.4 V
9
48) D) notch 49) D) 12.9 V
Figure 12- 2 50) What change would decrease the power factor in Figure 12-2? A) Decrease the value of the resistor. B) Increase the source voltage. C) Increase the value of the resistor. D) Decrease the source voltage.
50)
Figure 12- 1 51) If the frequency increases in Figure 12-1, the current _ _. A) remains the same B) decreases to zero C) increases D) decreases
51)
Figure 12- 2 52) If the resistance increased to 10 k▲ in Figure 12-2, the total impedance is A) 13.2 k▲ B) 6.61 k▲ C) 3.30 k▲ 53) Power in an RL circuit can be measured as: A) reactive power (Pr). C) true power (Ptrue).
. D) infinite ▲
52)
53) B) apparent power (Pa). D) all of these.
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 54) If the frequency increases in an RL circuit, the impedance decreases.
54)
55) If the resistance decreases in an RL filter circuit, the cutoff frequency increases.
55)
56) The impedance of an RL series circuit varies inversely with the frequency.
56)
10
57) The impedance of a series RL circuit is found by directly adding the values of XL and R.
57)
58) The impedance of a series RL circuit is found by adding the values of XL and R using a phasor diagram.
58)
59) The source voltage always lags the total current in an RL circuit.
59)
60) The source voltage always leads the total current in an RL circuit.
60)
61) A high-pass filter passes high frequencies and blocks low frequencies.
61)
62) The overall phase angle of a parallel circuit with a resistance of 20 ▲ and an inductive reactance of 25 k▲ would be nearly 90 degrees.
62)
63) An ohmmeter can be used to accurately test the impedance of an RL circuit.
63)
64) The output at the cutoff frequency of a low pass RL filter is 0 V.
64)
65) If the inductance increases in an RL filter circuit, the cutoff frequency increases.
65)
66) A low-pass filter passes high frequencies and blocks other frequencies.
66)
67) Power dissipated by the resistor in a parallel RL circuit can be increased with the addition of a capacitor in parallel.
67)
11
Answer Key Testname: CH 12
1) D 2) A 3) A 4) D 5) D 6) A 7) B 8) C 9) B 10) B 11) C 12) B 13) A 14) D 15) D 16) D 17) B 18) C 19) A 20) A 21) D 22) C 23) B 24) D 25) A 26) C 27) B 28) D 29) C 30) B 31) A 32) D 33) D 34) A 35) B 36) B 37) A 38) D 39) D 40) C 41) B 42) A 43) D 44) D 45) A 46) A 47) D 48) A 49) B 50) C 12
Answer Key Testname: CH 12
51) D 52) C 53) D 54) FALSE 55) FALSE 56) FALSE 57) FALSE 58) TRUE 59) FALSE 60) TRUE 61) TRUE 62) FALSE 63) FALSE 64) FALSE 65) TRUE 66) FALSE 67) TRUE
13
Chapter 13: RL MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The resonant frequency of a tank circuit with a 0.150 mH inductor and 300 pF capacitor is A) 6.05 MHz B) 750 kHz C) 347 kHz D) 1.65 MHz
.
2) In a series RLC circuit at resonance, the capacitive reactance (XC) and the inductive reactance (XL): A) are minimum. B) add to each other. C) cancel each other. D) are moderate.
1)
2)
Figure 13- 2 3) If the capacitor opens in Figure 13-2, the current _ _. A) decreases to zero B) remains the same C) increases because of the inductor D) continues to flow, but the circuit would not be resonant
3)
Figure 13- 1 4) If the frequency decreases in Figure 13-1, the impedance and the phase angle A) increases, increases B) decreases, increases C) increases, decreases D) decreases, decreases 5) A resonant circuit designed to reduce the interference from a specific source is called a A) wave trap B) shunt conductor C) break filter D) dropout filter
1
.
4)
5)
6) If a tank circuit is operating above resonance, it is A) resistive B) inductive
in nature. C) positive
6) D) capacitive
Figure 13- 1 7) If the resistance decreases in Figure 13-1, the impedance _. A) remains the same B) becomes zero C) increases D) decreases
7)
8) A resonant circuit with a high Q . A) has a very wide pass-band C) has a small voltage across the capacitor
8) B) tunes sharply D) has no pass-band
Figure 13- 2 9) If the current is 0 A in Figure 13-2, maybe A) the resistor is open C) the inductor is shorted
.
9) B) the resistor has changed values to 100 ▲ D) the capacitor is shorted
10) What is the power at f1 and f2 in a resonant circuit that delivers 120 W? A) 60 W B) 84.8 W C) 84.8 W at f1 and 60 W at f2 D) 17 W at both frequencies
10)
11) In a series RLC circuit at resonance: A) the impedance Z is at minimum.
11) B) the impedance is mostly resistive.
C) XC equals XL and they cancel.
D) all of these.
12) What is the bandwidth of a resonant circuit if its resonant frequency is 14.2 MHz, the inductive reactance is 3.5 k▲ and the coil's resistance is 8 ohm? A) 28.4 kHz B) 32.5 kHz C) 2285 Hz D) 14.2 MHz
2
12)
13) What is the VOUT/VIN ratio (expressed in dB) of an RLC series resonant circuit with the output across the inductor if the resonant frequency is 14 MHz, the source voltage is 12 V and the inductor drops 300 V? A) 25 dB B) 27.96 dB C) 13.98 dB D) 42.91 dB
13)
14) What is the power at f1 and f2 in a resonant circuit that delivers 750 W?
14)
A) 375 W at f1 and 750 W at f2 C) 750 W at both frequencies
B) 375 W at both frequencies D) 17 W at both frequencies
Figure 13- 1 15) If frequency increases in Figure 13-1, the impedance and the current A) increases, increases B) decreases, decreases C) decreases, increases D) increases, decreases
.
15)
16) In a parallel RLC circuit,at resonance the capacitive reactance (XC) and the inductive reactance (XL): A) are minimum. B) are moderate. C) add to each to cancel current flow. D) equal and oppose current flow.
16)
17) The output voltage of a circuit at 70.7% of its maximum level measured in dB is: A) -3 dB. B) 3 dB. C) 7 dB. D) -7 db.
17)
18) What is the resonant frequency of a tank circuit with a 150 mH inductor and a 300 pF capacitor? A) 2.37 MHz B) 237 kHz C) 23.7 Hz D) 23.7 kHz
18)
19) What is the resonant impedance of a series RLC circuit with a 15 mH inductor, 0.015 µF capacitor and 80 ▲ resistor? A) 80 ▲ B) 15 k▲ C) 30 ▲ D) 0 ▲
19)
20) What is the total current in a parallel resonant circuit if its impedance is 0.22 M▲, the Q is 100 and the source voltage is 100 V? A) 4.55 mA B) 45.5 mA C) 0.0455 mA D) 0.455 mA
20)
3
Figure 13- 1 21) If the frequency decreases in Figure 13-1, the impedance initially and the current initially . A) decreases, increases B) increases, increases C) decreases, decreases D) increases, decreases
21)
Figure 13- 2 22) At resonance, the current in Figure 13-2 is A) 10 mA B) 1.66 4
.
22) C) 1.66 mA
D) 10 A
23) In an ideal parallel resonant circuit, the total current into the L and C branches is A) high B) maximum C) zero D) low 24) If a tuned tank circuit has a very narrow bandwidth, its Q is probably A) below 10 B) very low C) very high
.
.
23)
24) D) about 10
25) In a series RLC circuit just below the resonant frequency, the impedance is: A) more capacitive. B) at maximum. C) more inductive. D) at minimum.
25)
26) What is the resonant frequency of a tank circuit with a 50 mH inductor and C = 256 pF capacitor? A) 44.5 kHz B) 445 kHz C) 44.5 Hz D) 4.45 kHz
26)
27) Which statement best describes the phase angle of a parallel RLC circuit at resonance? A) Total current flow is minimum. B) With a net reactance at minimum the phase angle is zero. C) With a net reactance at maximum the phase angle is zero. D) either A or C
27)
4
28) If an LC tank circuit is operating below resonance, the circuit is A) resistive B) capacitive C) positive
in nature. D) inductive
28)
29) What is the ratio of VOUT/VIN (expressed in dB) in an RLC series resonant circuit if the output voltage is taken across the inductor, the resonant frequency is 14 MHz, the source voltage is 18 V and the inductor drops 300 V? A) 28 dB B) 24.4 dB C) 14.0 dB D) 42.9 dB
29)
30) The selectivity of a given band-pass filter has degraded significantly, yet the fr is within tolerance. Which of the following could have caused this? A) The load has opened. B) The inductance has increased. C) The capacitance has increased. D) none of the above
30)
31) If a resonant circuit has a low Q, it . A) has a narrow pass-band C) has a small voltage across the capacitor
31) B) tunes sharply D) has a wide pass-band
32) What is the lower cut off frequency in an RLC resonant circuit if the inductive reactance is 1.2 k▲, the resonant frequency is 22 kHz and the resistance is 60 ▲? A) 21.7 kHz B) 21.8 kHz C) 21.5 kHz D) 20.9 kHz
32)
Figure 13- 2 33) If the resistor shorts in Figure 13-2, the current _ A) continues, but the circuit would not be resonant B) decreases C) does not change D) increases
_.
33)
34) In a parallel RLC just below the resonant frequency, the impedance is: A) more inductive. B) more capacitive. C) at minimum. D) at maximum.
34)
35) What is the current in a parallel RLC circuit if its impedance is 0.22 M▲, Q is 100 and VS = 50 V? A) 0.227 mA B) 2.27 mA C) 0.0227 mA D) 22.7 mA
35)
5
Figure 13- 1 36) To operate the circuit in Figure 13-1 at resonance, frequency. A) don't change, decrease C) don't change, increase
the resistance and B) decrease, decrease D) increase, increase
37) Find the voltage across the capacitor in Figure 13-1. A) 5.37 V B) 0.633 V
C) -4.9 V
the
36)
37) D) 10.7 V
Figure 13- 2 38) If the resistance increases in Figure 13-2, the bandwidth _ . A) decreases B) increases C) remains the same D) varies 39) If a tuned tank circuit has a very wide bandwidth, its Q might be _ A) about 10 B) very high C) very low
38)
_.
39) D) about 100
40) When tuning across the resonant frequency of a series RLC band-pass filter, which of the following is true? A) The output voltage across the load is minimum. B) Current flow through the load is minimum. C) The impedance of the filter should be maximum at resonance. D) The impedance of the filter should be minimum at resonance.
40)
41) The total reactance of a series RLC circuit at resonance is . A) zero B) infinity C) equal to the resistance D) capacitive
41)
6
42) In a parallel RLC circuit just above the resonant frequency, the impedance is: A) more inductive. B) more capacitive. C) at minimum. D) at maximum. 43) In a parallel resonant RLC circuit, the impedance is A) minimum, maximum C) maximum. maximum
and the total current is B) minimum, minimum D) maximum, minimum
42)
.
43)
44) To operate the circuit in Figure 13-1 below the resonant frequency, _ the resistance and the frequency. A) decrease, decrease B) do not change, decrease C) do not change, increase D) increase, increase
44)
45) In a series RLC circuit just above the resonant frequency, the impedance is: A) more capacitive. B) at maximum. C) more inductive. D) at minimum.
45)
46) Why does a resistive load increase the bandwidth of a given band-pass filter? A) The resistance decreases the quality of the circuit. B) A resistive load actually decreases the bandwidth. C) The resistance increases the quality of the circuit. D) not enough information
46)
Figure 13- 1
Figure 13- 1 47) If the resistance increases in Figure 13-1, the impedance _. A) remains the same B) decreases C) increases D) becomes zero
7
47)
48) What is the bandwidth of the resonant circuit if the resonant frequency is 1.42 MHz, the inductive reactance is 3.5 k▲ and the coil's resistance is 8 ohm? A) 3.25 kHz B) 32.5 kHz C) 1.42 MHz D) 2285 Hz
48)
Figure 13- 2 49) If the resistance decreases in Figure 13-2, the bandwidth _ . A) varies B) increases C) decreases D) remains the same
49)
50) If the resonant frequency is 1 MHz and Q = 50, f1 = A) 0.98 MHz, 1.01 MHz C) 0.98 MHz, 1.02 MHz
50)
and f2 = . B) 0.99 MHz, 1.02 MHz D) 0.99 MHz, 1.01 MHz
51) What is the source voltage in a series resonant circuit if VC = 150 V, VL = 150 V and VR = 50 V? A) 50 V B) 150 V C) 300 V D) 350 V
51)
52) Replacing the inductor in a series resonant band-pass filter with one having a lower Q value causes the bandwidth to . A) remain the same B) increase C) decrease D) be more selective
52)
Figure 13- 1 53) As the frequency approaches the resonant frequency in Figure 13-1, the VR . A) remains the same B) decreases C) increases D) becomes increasingly unstable
53)
54) For the tuning circuit of a radio frequency receiver, the filter: A) bandwidth should be narrow. B) high Q components are not necessary. C) need not be highly selective. D) any of the above
54)
8
55) Between the lower and upper critical frequencies of a band-pass filter: A) the frequencies pass at 70% to their maximum levels. B) the frequencies pass a maximum level. C) the frequencies pass at 30% to their maximum levels. D) the frequencies pass a minimum level.
55)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 56) In a resonant circuit, as Q increases the bandwidth decreases.
56)
57) At resonance, a series RLC circuit has maximum current.
57)
58) A highly selective filter has a very wide bandwidth.
58)
59) The true power of an RLC circuit depends on the value of resistance.
59)
60) At resonance, XC equals XL.
60)
61) A series RLC circuit can be configured for band-pass or band-stop filtering purposes.
61)
62) At resonance, the impedance of a series RLC circuit equals its resistance.
62)
63) The capacitor's resistive effects are significant when considering the Q of an RLC circuit.
63)
64) A resonant RLC circuit is said to be very selective if its Q is very low.
64)
65) The total impedance equals the resistance of a resonant series RLC circuit.
65)
66) At resonance, a parallel RLC circuit is capacitive.
66)
67) In a parallel resonant circuit, the impedance is minimum and the line current is maximum.
67)
68) Current leads in a series RLC circuit with more capacitive reactance than inductive reactance.
68)
69) At resonance, a parallel RLC circuit is inductive.
69)
70) In a series resonant circuit, the impedance is minimum and the current is maximum.
70)
9
Answer Key Testname: CH 13
1) B 2) C 3) A 4) D 5) A 6) D 7) D 8) B 9) A 10) A 11) D 12) B 13) B 14) B 15) D 16) D 17) A 18) D 19) A 20) D 21) A 22) D 23) C 24) C 25) A 26) A 27) D 28) D 29) B 30) D 31) D 32) C 33) D 34) A 35) A 36) A 37) A 38) B 39) C 40) D 41) A 42) B 43) D 44) B 45) C 46) A 47) C 48) A 49) C 50) D 10
Answer Key Testname: CH 13
51) A 52) B 53) C 54) A 55) A 56) TRUE 57) TRUE 58) FALSE 59) TRUE 60) TRUE 61) TRUE 62) TRUE 63) FALSE 64) FALSE 65) TRUE 66) FALSE 67) FALSE 68) TRUE 69) FALSE 70) TRUE
11
Chapter 14: Transformers MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Figure 14- 1 1) In Figure 14-1, the primary to secondary turns ratio is changed to 2.5:1 and the secondary current equals 100 mA. What is the reflected resistance seen by the primary? A) 1.2 k▲ B) 2.5 k▲ C) 5 k▲ D) 3 k▲
1)
2) What is the likeliest way to fix a center-tapped transformer which outputs unequal voltages on each half of the secondary? A) Do not concern yourself; the customer will probably not notice the problem. B) Remove some turns from the half with the higher voltage winding. C) Replace the transformer. D) Add some turns to the half with the lower voltage winding.
2)
Figure 14- 1 3) What is the secondary voltage in Figure 14-1 if the turns ratio is 7:1? A) 8.59 VRMS B) 17.1 VRMS C) 420 VRMS
3) D) 840 VRMS
4) In Figure 14-1, if there are five times more turns in the primary than in the secondary, then what is the secondary voltage? A) 24 V B) 600 V C) 120 V D) 12 V
4)
5) What is the secondary voltage in Figure 14-1 if the turns ratio is 4.5:1? A) 26.7 V B) 5.92 V C) 4.72 V
5) D) 540 V
6) If you wanted to monitor a large alternating current without opening the circuit you would likely use a . A) current-sensing inductor B) step-down transformer C) current transformer D) any of the above
6)
7) To couple two circuits together with no change in either voltage or current, use A) a step-up transformer B) a step-down transformer C) an isolation transformer D) a power transformer
7)
1
.
Figure 14- 1
10)
8) What is the secondary current in Figure 14-1 with a 50 ▲ load resistor and 4:1 turns ratio? A) 9.6 A B) 600 mA C) 1.66 A D) 4.8 A
8)
9) An autotransformer differs from most transformers in that: A) source current flows through both the windings. B) primary and secondary windings are the same. C) it does not isolate the primary voltage from the secondary voltage. D) all of these.
9)
A matching transformer's primary needs more turns than its secondary to match a 600 ▲ audio signal distribution line to an 8 ▲ speaker. A) 0.013 B) 0.115 C) 8.66 D) 75
10)
11) Which winding will have the lowest measured resistance in a transformer with four secondary windings? A) the 6.3 V secondary B) the 5 V secondary C) the 550 V secondary D) the 12 V secondary
11)
12) An air core transformer would most likely be used for: A) radio frequencies. B) audio frequencies. C) impedance matching. D) isolation.
12)
13) If a 12 V battery is connected across the primary of a transformer with a turns ratio of 1:4, then the secondary voltage is . A) 0 V B) 48 V C) 3 V D) 12 V
13)
Figure 14- 1 14) In Figure 14-1, if the secondary current is 50 mA, the reflected resistance seen by the primary equals _ . A) 2.4 k▲ B) 14.4 k▲ C) 7.2 k▲ D) 800 ▲
14)
15) For a transformer to operate properly, it must: A) be connected to a load. B) work within its voltage, current and power ratings. C) be supplied with the proper AC signal. D) all of these.
15)
2
Figure 14- 1 16) In Figure 14-1, if a load resistor of 75 ▲ is placed in the secondary circuit, what is the secondary current? A) 16 A B) 5.33 A C) 4.8 A D) 533 mA
16)
17) When a 1 k▲ load resistor is connected across the secondary winding of a transformer with a turns ratio of 1:2, the source "sees" a reflected load of . A) 2 k▲ B) 1 k▲ C) 4 k▲ D) 250 ▲
17)
18) A center tap transformer has a connection at the midpoint of the secondary winding resulting in: A) two 180 degree out of phase secondary voltages. B) two equal magnitude secondary voltages. C) secondary voltages half that of a non-center tapped transformer with the same turns ratio. D) all of these.
18)
19) In induction heating, the material is heated due to A) eddy currents C) hysteresis
19)
. B) high load reactance D) the fact that the material acts like an open
Figure 14- 1 20) What is the reflected resistance seen by the primary in Figure 14-1 if the turns ratio is 4:1 and IS is 40 mA? A) 4 k▲ B) 16 k▲ C) 8 k▲ D) 12 k▲ 21) In Figure 14-1, if the primary to secondary turns ratio is 7.5:1, the output voltage equals A) 32 VRMS B) 900 VRMS C) 9 VRMS D) 16 VRMS 22) In Figure 14-1, the primary to secondary turns ratio is 1:3 and the secondary current equals 120 mA. What is the primary current? A) 40 mA B) 360 mA C) 180 mA D) cannot compute because the voltage is not given
3
20)
.
21)
22)
23) The hysteresis loss in a transformer is _. A) another name for flux leakage loss B) caused by the resistance of the wire C) caused by rapid reversal of the magnetic field D) caused by current flowing in the core
23)
24) How can the windings ratio be safely determined for an unmarked transformer? A) Apply known low voltage ac to the primary and measure the secondary output. The ratio of the voltages is the same as the windings ratio. B) The turns ratio is the same as the ratio of primary resistance to secondary resistance ratio. C) Standardized wire color codes indicate windings ratio. D) either A or C
24)
25) What type transformer most likely has a 1:1 turns ratio? A) isolation B) center tapped C) impedance matching D) power
25)
26) The relationship for the current ration (Isec/Ipri) in a transformer is: A) the inverse of the turns ratio (Nsec/Npri). B) less than the turns ratio (Nsec/Npri). C) more than the turns ratio (Nsec/Npri). D) the same as the turns ratio (Nsec/Npri).
26)
27) A step-up transformer will increase _ A) voltage, power C) current, impedance
27)
_ and decrease . B) voltage, impedance D) power, current
28) Although the input voltage to the transformer's primary is correct, the transformer is outputting zero volts. A probable trouble is . A) a partially shorted secondary B) a partially shorted primary C) an open primary D) a shorted primary
28)
Figure 14- 1 29) What is the primary current in Figure 14-1 if IS = 40 mA and the turns ratio equals 4:1 ? A) 4 mA B) 40 mA C) 160 mA D) 10 mA
29)
30) What is the secondary current in Figure 14-1 with a 100 ▲ load resistor and 3:1 turns ratio? A) 40 mARMS B) 330 mARMS C) 400 mARMS D) 33 mARMS
30)
31) The measured voltage on the secondary of a given transformer is 0 V. Which of the following could have caused this? A) shorted load B) open primary C) open secondary D) any of the above
31)
4
32) The phrase "Maximum power is delivered to the load when the load resistance equals the source resistance" is a definition of . A) Kirchhoff's Law B) the maximum power transfer theorem C) Lenz's Law D) Ohm's Law
32)
Figure 14- 1 33) What is the primary current in Figure 14-1 if the turns ratio equals 1:3 and IS equals 240 mA? A) 720 mA B) 60 mA C) 120 mA D) 1.2 A
33)
34) When the turns ratio of a transformer is 1:10 and the primary AC voltage in 6 V, then the secondary voltage is _ . A) 0.6 V B) 60 V C) 6 V D) 36 V
34)
35) Transformers . A) match the impedance of a source to the impedance of a load B) convert a lower current into a higher current C) convert a higher voltage into a lower voltage D) all of these
35)
Figure 14- 1 36) What is the reflected resistance seen by the primary in Figure 14-1 if the turns ratio is 3:1 and IS is 240 mA? A) 9000 ▲ B) 167 ▲ C) 1500 ▲ D) 500 ▲
36)
37) In Figure 14-1, if the primary to secondary turns ratio is changed to 4:1 and a 1 k▲ load resistor is in the secondary, the secondary current equals _. A) 30 mA B) 240 mA C) 120 mA D) 480 mA
37)
38) The small dot placed on schematics of transformers indicates: A) the direction of the winding. B) the phase of the voltages. C) the polarity of the voltages. D) all of these.
38)
39) The reflected load in a transformer is defined as the actual load as it appears to the source and results from: A) the voltage ratio. B) the power ratio. C) the current ratio. D) the turns ratio.
39)
5
40) What is the problem if a power transformer is delivering a low output voltage even though the primary voltage is correct? A) an open primary B) a partially shorted secondary C) an open secondary D) a shorted primary
40)
41) 36 V of dc is applied to a windings ratio of 1:2. What is the secondary voltage? A) 144 V B) something slightly less than 72 V since transformers do have some loss C) 72 V D) none of the above
41)
42) A step-up transformer will increase _ A) current, impedance C) current, voltage
42)
_ and decrease . B) impedance, current D) voltage, impedance
43) When a 1 k▲ load resistor is connected across the secondary winding of a transformer with a turns ratio of 2:1, the source "sees" a reflected load of . A) 4 k▲ B) 1 k▲ C) 2 k▲ D) 500 ▲
43)
44) If 10 W of power are applied to the primary of an ideal transformer with a turns ratio of 1:5, the power delivered to the secondary load is _. A) 0 W B) 10 W C) 0.5 W D) 50 W
44)
45) The turns ratio required to match a 50 ▲ source to a 200 ▲ load is A) 4:1 B) 1:2 C) 2:1
45)
. D) 1:4
46) The relationship for the voltage ratio (Vsec/Vpri) in a transformer is: A) opposite to the turns ratio (Nsec/Npri). B) the same as the turns ratio (Nsec/Npri). C) more than the turns ratio (Nsec/Npri). D) less than the turns ratio (Nsec/Npri).
46)
Figure 14- 1 47) What is the secondary voltage in Figure 14-1 if the turns ratio is 1:3? A) 360 VRMS B) 40 VRMS C) 80 VRMS
D) 240 VRMS
48) What is the secondary voltage in Figure 14-1 if the turns ratio is 9:1? A) 26.6 V B) 13.3 V C) 106 V
D) 53.2 V
49) In Figure 14-1, if the secondary current is 50 mA, the primary current is A) 150 mA B) 48.7 mA C) 300 mA
. D) 50 mA
6
47)
48)
49)
50) To match a 600 ▲ audio load to a 4 ▲ speaker system, the primary of the impedance matching transformer must have more turns than the secondary. A) 3.06 B) 12.2 C) 150 D) The primary should have less turns than the secondary.
50)
51) The relationship for the impedance matching ratio (RL/Rpri) in a transformer is:
51)
A) opposite to the turns ratio (Nsec/Npri) squared. B) equal to the turns ratio (Nsec/Npri). C) opposite to the turns ratio (Nsec/Npri). D) equal to the turns ratio (Nsec/Npri) squared. 52) Eddy current loss in a transformer is _. A) caused by rapid reversal of the magnetic field B) due to current flowing in the core C) caused by the resistance of the wire D) another name for flux leakage loss
52)
Figure 14- 1 53) In Figure 14-1, if the primary to secondary turns ratio is 9:1 and a 1 k▲ load resistor is placed in the secondary, the reflected resistance seen by the primary equals . A) 162 k▲ B) 1 k▲ C) 81 k▲ D) 111 ▲
53)
54) The turns ratio of a transformer (n) is defined as: A) the number of turns in the primary multiplied by the number of turns in the secondary. B) the number of turns in the secondary multiplied by the number of turns in the primary. C) the number of turns in the secondary divided by the number of turns in the primary. D) the number of turns in the primary divided by the number of turns in the secondary.
54)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 55) A step-down transformer could have a primary-secondary turns ratio of 4:1.
55)
56) Only the number of turns in the primary and secondary of a transformer determines the actual secondary voltage.
56)
57) A core material is not always necessary for proper operation of a transformer.
57)
58) A transformer with a turns ratio of 1:1 is often used to isolate a load from a source.
58)
59) A typical transformer fault would be an open winding.
59)
7
60) An ideal transformer has no power loss.
60)
61) If a dc voltage is input to a transformer's primary, then an ac voltage is induced in its secondary.
61)
62) The efficiency of all transformers is very low.
62)
63) Autotransformers cannot be used for isolation purposes since there is only one winding.
63)
64) The impedance matching characteristic for a transformer is needed for a situation where maximum power transfer to the load is desired.
64)
65) A transformer can be used as an impedance matching device.
65)
66) A transformer with a turns ratio of 1:7 is a step down transformer.
66)
67) Transformer cores are made from laminated iron to reduce losses.
67)
68) An ideal 10:1 transformer with 20 VA of power has less than 2 VA on the output.
68)
69) The primary to secondary resistance should be relatively low.
69)
8
Answer Key Testname: CH 14
1) D 2) C 3) B 4) A 5) A 6) C 7) C 8) B 9) D 10) C 11) B 12) A 13) A 14) D 15) D 16) C 17) D 18) D 19) A 20) D 21) D 22) B 23) C 24) A 25) A 26) A 27) B 28) C 29) D 30) C 31) D 32) B 33) A 34) B 35) D 36) C 37) A 38) D 39) D 40) B 41) D 42) B 43) A 44) B 45) B 46) B 47) A 48) B 49) A 50) B 9
Answer Key Testname: CH 14
51) D 52) B 53) C 54) C 55) TRUE 56) FALSE 57) TRUE 58) TRUE 59) TRUE 60) TRUE 61) FALSE 62) FALSE 63) TRUE 64) TRUE 65) TRUE 66) FALSE 67) TRUE 68) FALSE 69) FALSE
10
Chapter 15: Time Response of Reactive Circuits MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) What is VC at the end of the input pulse to an RC integrator if the input pulse is 12 V and the pulse width equals one time constant? A) 7.59 V B) 4.41 V C) 12 V D) 0 V
1)
2) What is the output voltage at the end of the input pulse from an RL integrator that uses a 400 mH inductor, a 5 k▲ resistor and a 5 V, 1.2 ms input pulse? A) 4.532 V B) 5 V C) 3.16 V D) 4.75 V
2)
3) A pulse-waveform to DC convertor makes use of an integrator: A) with a time constant shorter than the width of the input pulse. B) with a time constant much wider than the width of the input pulse. C) with an extremely large time constant. D) either B or C
3)
4) What is the output voltage from an RL integrator that uses a 10 mH inductor, a 10 ▲ resistor and a 16 V, 1 ms input pulse? A) 15.2 V B) 10.1 V C) 13.8 V D) 16.3 V
4)
5) In RC and RL integrators and differentiators, transient time is equal to the: A) pulse width. B) time constant times five. C) pulse width times five. D) time constant.
5)
6) What is the output voltage at the end of the input pulse to an RL integrator if the resistance is 1.2 k ▲, the inductor is 200 mH and the input is a 5 V, 1.2 ms pulse? A) 4.75 V B) 4.532 V C) 3.16 V D) 5 V
6)
7) How long will it take a 0.047 µF capacitor to completely discharge through a 10 k▲ resistor? A) 2.35 ms B) 0.47 ms C) 5 s D) 0.18 ms
7)
8) Pulse width (tW) is defined as: A) the time interval between opposite points on the pulse. B) the time interval between identical points on the pulse. C) the time interval between changes in the pulse. D) all of these.
8)
9) The output from an RL differentiator is taken across the _ _. A) resistor B) resistor and inductor C) source D) inductor
9)
10) How does the RC differentiator output look when 5L is much longer than the pulse width? A) positive spikes B) negative spikes C) square waves D) positive and negative spikes
10)
1
11) If you want to monitor the frequency response of an RF circuit in real time, the circuit is driven by a swept-frequency generator and the output is monitored using a scope. The scope must _. A) have at least 10 times the bandswidth of the highest test frequency B) change its time base to match the generator C) be in x- y mode. D) all of the above
11)
12) A given circuit using an RC integrator to turn on after 20 seconds now takes now takes much longer to turn on. What is the most probable cause? A) The resistor has decreased in value. B) The resistor has opened. C) The capacitor has decreased in value. D) The capacitor has increased in value.
12)
13) If the input pulse to an RC differentiator is very short compared to the circuit's time constant, then the differentiator's output is _. A) a dc voltage equal to the peak input voltage B) a square wave very similar to the input voltage C) a dc value of about half the peak input voltage D) zero volts
13)
14) A timing circuit makes use of which of the following? A) RC Differentiator B) RL differentiator C) RC integrator D) either A or C
14)
15) What is the output voltage at the end of the input pulse to an RL integrator if the resistance is 1 k▲, the inductor is 1 H and the input is a 22 V, 2 ms pulse? A) 19.0 V B) 13.9 V C) 20.9 V D) 21.6 V
15)
16) What is the time constant in an RC integrating circuit if a 10 k▲ resistor is in series with a 220 µF capacitor? A) 2.2 ms B) 2.2 s C) 22 ms D) 0.22 ms
16)
17) How long will it take to completely charge a 0.22 µF capacitor through a 5.2 M▲ resistor? A) 1.14 s B) 4.58 s C) 5.72 s D) 2.29 s
17)
18) The output from an RC integrator resembles the input if _. A) L is less than the pulse width B) L is much larger that the pulse width C) L is equal to the pulse width D) L is much less than the pulse width
18)
19) The output of an RL integrator is taken across the _ A) inductor C) resistor and inductor
19)
. B) resistor D) source
20) Polarity of the output of an RL differentiator is determined by: A) the placement of the inductor. B) the polarity of the incoming pulse. C) an external clipping circuit. D) the time constant of the RL circuit.
20)
21) How long will it take to completely discharge a 0.47 µF capacitor through a 10 k▲ resistor? A) 0.47 ms B) 23.5 ms C) 2.35 s D) 0.18 ms
21)
2
22) What is the output voltage at the end of the input pulse to an RC integrator if the resistance is 12 k ▲, the capacitance is 10 µF and the input is a 50 V, 1 s pulse? A) 43.25 V B) 50 V C) 47.5 V D) 31.6 V
22)
23) What is output voltage at the end of the input pulse to an RC integrator if the resistance is 10 k▲, the capacitance is 100 µF and the input is a 50 V, 10 s pulse? A) 31.6 V B) 43.25 V C) 50 V D) 47.5 V
23)
24) What is VC at the end of the input pulse to an RC integrator if the resistance is 5 k▲, the capacitance is 0.47 µF and the input is a 15 V, 4.7 ms pulse? A) 14.3 V B) 9.48 V C) 14.7 V D) 13.0 V
24)
25) What is the output voltage at the end of the input pulse from an RL integrator that uses a 2 H inductor, a 10 k▲ resistor and a 32 V, 0.4 ms input pulse? A) 21.6 V B) 13.9 V C) 27.7 V D) 19.0 V
25)
26) How does the RC differentiator output look when 5L is much less than the pulse width? A) positive spikes B) negative spikes C) square waves D) positive and negative spikes
26)
27) What is one time constant in an integrating circuit if a 4.7 k▲ resistor is in series with a 0.005 µF capacitor? A) 235 ms B) 0.0235 ms C) 0.00235 ms D) 2.35 ms
27)
28) The output from an RC differentiator resembles the input if _. A) L is less than the pulse width B) L is much larger that the pulse width C) L is much less than the pulse width D) L is equal to the pulse width
28)
29) To charge a 100 µF capacitor in 15 seconds, use a _ A) 35 k▲ B) 25 k▲
29)
resistor. C) 15 k▲
D) 30 k▲
30) What is VC at the end of the input pulse to an RC integrator if the resistance is 5 k▲, the capacitance is 47 µF and the input is a 15 V, 470 ms pulse? A) 14.3 V B) 13 V C) 9.48 V D) 14.7 V
30)
31) If the input pulse to an RC differentiator is very short compared to the circuit's time constant, the differentiator's output is _. A) a dc value of about half the peak input voltage B) a square wave very similar to the input voltage C) a dc voltage equal to the peak input voltage D) zero volts
31)
32) What is VC at the end of the input pulse to an RC integrator if the input pulse is 15 V and the pulse width equals one time constant? A) 9.48 V B) 14.25 V C) 14.7 V D) 13.0 V
32)
3
33) A given circuit using an RC integrator to turn on after 20 seconds now takes has been taking much longer to turn on. Now it entirely fails to turn on. What is the problem? A) The capacitor has increased in value. B) The resistor has decreased in value. C) The capacitor has decreased in value. D) The resistor has opened.
33)
34) What is one time constant in an integrating circuit if a 47 k▲ resistor is in series with a 0.01 µF capacitor? A) 0.47 s B) 0.047 µs C) 0.047 ms D) 0.47 ms
34)
35) If a square wave input produces 0 V output from an RC integrator, . A) the capacitor is leaky B) the resistor is shorted C) the resistor is open D) the capacitor is open
35)
36) What is the output voltage at the end of the input pulse from an RL integrator that uses a 200 mH inductor, a 22 k▲ resistor and a 12 V, 9.09 µs input pulse? A) 11.4 V B) 7.59 V C) 10.38 V D) 11.76 V
36)
37) RC and RL integrators produce an output voltage that equals the: A) mathematical product. B) mathematical sum. C) mathematical difference. D) mathematical average.
37)
38) The capacitor of an RC integrator charges to equal to one time constant. A) 19.0 V B) 28.5 V
38)
_ if the input is a 30 V pulse with a pulse width C) 29.4 V
D) 26.0 V
39) RC integrators can be used in timing circuits to set a specified time delay if the output is coupled to: A) a voltage threshold sensitive circuit. B) a power threshold sensitive circuit. C) a voltage generating circuit. D) a current sensitive circuit.
39)
40) What is VC at the end of the input pulse to an RC integrator if the resistance is 22 k▲, the capacitance is 0.05 µF and the input is a 12 V, 2.2 ms pulse? A) 4.42 V B) 12 V C) 10.4 V D) 7.58 V
40)
41) What is one time constant in an integrating circuit if a 10 k▲ resistor is in series with a 470 µF capacitor? A) 4.7 s B) 0.047 µs C) 0.47 µs D) 0.47 ms
41)
42) What is the time constant in an RC integrating circuit if a 22 k▲ resistor is in series with a 0.02 µF capacitor? A) 0.44 s B) 0.044 µs C) 0.044 ms D) 0.44 ms
42)
43) How long will it take a 22 µF capacitor to completely charge through a 1.2 M▲ resistor? A) 132 s B) 2.64 s C) 13.2 s D) 0.264 s
43)
44) RC and RL integrators provide the same output when the inputs are A) different B) the outputs are never the same C) the same
44)
4
.
45) RC and RL differentiators produce an output voltage that closely approximates the: A) mathematical rate of change process. B) mathematical average. C) mathematical sum. D) mathematical difference.
45)
46) What is output voltage at the end of the input pulse to an RL integrator if the resistance is 22 k▲, the inductor is 2 H and the input is a 12 V, 0.0909 ms pulse? A) 10.4 V B) 11.4 V C) 7.59 V D) 11.8 V
46)
47) The capacitor of an RC integrator charges to equal to six time constants. A) 3.7 V B) 10 V
47)
_ if the input is a 10 V pulse with a pulse width C) 5 V
D) 6.3 V
48) RC integrators can be used to convert a repetitive pulse waveform to a constant dc voltage equal to the average voltage of the waveform if: A) L is very small compared to tW. C) L is very large compared to tW. 49) The capacitor of an RC integrator charges to equal to one time constant. A) 10 V B) 6.3 V
48)
B) L is equal to tW. D) L is five times tW. _ if the input is a 10 V pulse with a pulse width C) 3.7 VC
49)
D) 5 V
50) If an RC integrator uses a 47µF capacitor, a 12 k▲ resistor and a square wave input with a frequency of 200 kHz, its approximate output is _ . A) 0 V B) a square wave with a frequency of 100 kHz C) a square wave with a frequency of 200 kHz D) a near dc voltage of about half the peak square wave voltage
50)
51) To completely charge a 500 µF capacitor in 15 seconds, use a _ A) 12 k▲ B) 18 k▲ C) 24 k▲
51)
resistor. D) 6 k▲
52) If RC and RL differentiators with equal time constants receive the same pulse, _ . A) one outputs an increasing exponential while the other outputs a decreasing exponential B) the RC has the widest output pulse C) you can't tell the difference by observing the output wave forms D) the RL has the most narrow spikes on the output
52)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 53) In an RC integrator, as the time constant gets longer, the maximum capacitor voltage gets smaller.
53)
54) A watchdog circuit is used to monitor for a particular condition in a circuit so that corrective action can be taken.
54)
55) The output from an RL integrator can look exactly the same as the output from an RC integrator.
55)
56) An RC integrating circuit is a basic high-pass filter with a pulse applied to it.
56)
57) The output of an RC integrator is the capacitor's voltage drop.
57)
5
58) The output of a differentiator circuit will reach the same maximum and minimum levels as the input as long as the time constant of the circuit is less than the width of the input pulse.
58)
59) The output of an RC differentiating circuit is taken across the resistor.
59)
60) The output of an RC differentiator with an open capacitor will look like the input.
60)
61) In an RC integrating circuit, the output is taken across the capacitor.
61)
62) When the input pulse width to an RC integrator is much less than 5L, the output approaches the shape of the input.
62)
63) An open inductor in an RL differentiator will cause the output to resemble the input.
63)
64) It takes a capacitor 5 time constants to nearly reach full charge.
64)
65) Since voltage is constant during the peak of a pulse input, the output of an LC integrator is constant during this time as well.
65)
66) LC and RC integrators, with respect to input and output, perform exactly the same.
66)
67) In an RL integrating circuit, the output is taken across the inductor.
67)
68) An RL integrator is a basic RL low-pass filter with a pulse applied to it.
68)
6
Answer Key Testname: CH 15
1) A 2) B 3) D 4) B 5) B 6) D 7) A 8) A 9) D 10) C 11) C 12) D 13) B 14) C 15) A 16) B 17) C 18) D 19) B 20) C 21) B 22) B 23) C 24) D 25) C 26) D 27) B 28) B 29) D 30) B 31) B 32) A 33) D 34) D 35) C 36) B 37) D 38) A 39) A 40) C 41) A 42) D 43) A 44) C 45) A 46) C 47) B 48) C 49) B 50) D 7
Answer Key Testname: CH 15
51) D 52) C 53) TRUE 54) TRUE 55) TRUE 56) FALSE 57) TRUE 58) FALSE 59) TRUE 60) FALSE 61) TRUE 62) FALSE 63) TRUE 64) TRUE 65) FALSE 66) TRUE 67) FALSE 68) TRUE
8
Chapter 16: Diodes and Applications TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 1) A full-wave rectifier is easier to filter than a half-wave rectifier.
1)
2) The arrowhead in the diode symbol points in the direction of electron flow.
2)
3) A semiconductor has an energy gap that is much narrower than that in an insulator.
3)
4) The atoms within the silicon crystal structure are held together by covalent bonds.
4)
5) Reverse current is dependent primarily on junction temperature and not on the amount of reverse-biased voltage.
5)
6) An intrinsic crystal is inherently doped.
6)
1
Answer Key Testname: CH 16
1) TRUE 2) FALSE 3) TRUE 4) TRUE 5) TRUE 6) FALSE
2
Chapter 17: Transistors and Applications MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A transistor is in the cutoff region when the A) collector current is at its peak value B) base current is at its peak value C) base-collector junction is forward biased D) base-emitter junction is not forward biased
.
2) If a sinusoidal wave is the desired output of an oscillator, the loop gain must be equal to A) L B) 1 C) 0 D) 1/L
1)
.
2)
3) When both the junctions of a bipolar junction transistor are forward-biased, the transistor is said to be in its saturation region.
3)
4) A push-pull class B amplifier has a lower efficiency than a class A amplifier.
4)
5) The basic construction of an enhancement MOSFET does not have a structural channel.
5)
6) In a bipolar junction transistor, the base material is the most heavily doped.
6)
7) A saturated transistor is assumed to act as a short from collector to emitter.
7)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
1
Answer Key Testname: CH 17
1) D 2) B 3) TRUE 4) FALSE 5) TRUE 6) FALSE 7) TRUE
2
Chapter 18: The Operational Amplifier MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Which of the following features of an op-amp prevents it from hanging up in one output state? A) input offset nulling B) external potentiometer C) clipping protection D) no-latch-up
1)
2) In common-mode input, if the output signals cancel each other out, then the A) input signal has been applied to only one end B) input signals are identical but out of phase C) input signals are of equal amplitude and frequency, but opposite polarity D) input signals are identical and in phase
2)
.
3) Which of the following is true about input offset voltage? A) Input offset voltage drift is of the order of 5 mV per degree Celsius. B) The input offset voltage should ideally be 2 mV or more. C) The input offset voltage is the common mode input required to force a differential output of zero volts. D) A higher nominal value of input offset voltage indicates a higher drift.
3)
4) Which of the following is true about an inverting amplifier? A) A practical inverting amplifier has a lower differential input than a voltage follower.
4)
B) Voltage across Ri is equal to Vout if Rf=Ri. C) The voltage across Rf is equal to -Vin. D) Its closed loop gain depends on the internal open-loop gain.
Figure 18-4 5) If Ri = 1.2 k▲, Rf = 130 k▲, Rin = 6 M▲, Rout = 85 ▲, and Aol = 70,000 in Figure 18-4, find the value of the output resistance. A) 106.48 m▲
B) 125.04 m▲
C) 132.56 m▲
1
D) 112.45 m▲
5)
6) Which of the following leads to the output signal being clipped on only one peak? A) lack of power supply B) open input resistor C) open feedback resistor D) open or incorrectly adjusted offset null potentiometer
6)
Figure 18-3 7) If Ri =15 ▲, Rf =180 ▲, Rin = 4 M▲, Rout = 75 ▲, and Aol = 135,000 in Figure 18-3, the input resistance of the amplifier is _ _. A) 37.4 G▲ B) 41.5 G▲
C) 3850 M▲
7)
D) 5475 M▲
Figure 18-2 8) The differential amplifier shown in Figure 18-2 has a CMRR of 25,000 and a differential voltage gain of 3500. In part (a), a single-ended input signal of 700 µV rms is applied. At the same time a 100 mV, 60 Hz common-mode interference signal appears on both inputs. In part (b), differential input signals of 700 µV rms each are applied to the inputs. The common-mode interference is the same as in part (a). Calculate the common mode gain. A) 0.3 B) 0.04 C) 0.2 D) 0.14
2
8)
9) Which of the following is true of a noninverting amplifier?
9)
A) The feedback fraction is determined by Rf, Ri, and Vin. B) The closed-loop gain of a noninverting amplifier depends on the open-loop gain of the op-amp. C) The closed-loop voltage gain is the voltage gain of an op-amp with negative feedback. D) The feedback network connects the output to the noninverting input. 10) When a differential amplifier is operated in single-ended mode, the transistor whose input is grounded functions as a amplifier. A) common-emitter B) push-pull C) common-base D) common-collector
10)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 11) When a differential amplifier receives input at a single-end, the output of the transistor that receives the input signal has the same phase as the input signal.
11)
12) A differential amplifier produces an output proportional to the difference of its two inputs.
12)
13) Common-mode input resistance is the resistance between each input and ground.
13)
3
Answer Key Testname: CH 18
1) D 2) D 3) D 4) B 5) C 6) D 7) B 8) D 9) C 10) C 11) FALSE 12) TRUE 13) TRUE
4
Chapter 19: Basic Op-Amp Circuits MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Which of the following is true about integrators and differentiators? A) When the input to an integrator is a square wave, its output is a sinusoidal wave. B) Capacitors are connected in parallel with the op-amp in differentiators and in series in integrators. C) Differentiating circuits can generate triggers from a pulse, but integrating circuits cannot. D) Differentiators have a virtual ground at their inverting inputs, but integrators do not.
1)
2) In a square wave relaxation oscillator . A) the output is a negative maximum when the capacitor is uncharged B) the op-amp switches to the negative maximum when the capacitor voltage reaches a value equal to the feedback voltage on the noninverting input. C) the op-amp switches to the maximum positive state when the capacitor starts discharging from its peak value D) the inverting input is a portion of the output fed back through resistors
2)
Figure 19-6 3) If only R1 and VIN1 are present in the circuit shown in Figure 19-6, then it represents a(n) . A) differentiator C) integrator
B) noninverting amplifier D) inverting amplifier
4) If Rf = 15 k▲ and C = 1.7 nF in part (b), calculate the time constant. A) 8.82 µs
3)
B) 51 µs
C) 25.5 µs
1
4) D) 132.35 µs
Figure 19-6 5) The circuit in Figure 19-6 will be an averaging amplifier if A) VIN1 = VIN2 = VIN3 B) VIN1 = VIN2 = VIN3 and Rf = (R1 + R2 + R3)/3 C) Rf = (R1 + R2 + R3)/3 D) R1 = R2 = R3 and Rf/R = 1/3
2
.
5)
Figure 19-7 6) For the circuit shown in part (a) of Figure 19-7, C = 13 nF, Ri = 30 k▲, Rf = 450 k▲, and Vin varies from +3 V to -3V. Calculate the rate of change of output voltage during the time the capacitor is charging. A) -15.1 kV/s
B) -7.69 kV/s
C) -13.24 kV/s
3
D) -6.67 kV/s
6)
Figure 19-6 7) In Figure 19-6, VIN1 = +6 V, VIN2 = +5 V, VIN3 = +9 V, R1 = 63 k▲, R2 = 20 k▲, Rf = 50 k▲, and VOUT = -27.26 V. Determine the value of R3. A) 25 k▲
B) 35 k▲
C) 30 k▲
7)
D) 45 k▲
8) A scaling adder . A) has an output voltage equal to the sum of the input values B) is obtained by setting the ratio of Rf/R equal to the reciprocal of the number of inputs
8)
C) can adjust the weight of each input by varying the values of the input resistors D) calculates the simple mathematical average of the input values 9) Which of the following is true of a triangular-wave oscillator? A) The frequency of oscillation can be adjusted without changing the output amplitude, if R1 is
9)
varied. B) The comparator's output is connected to the noninverting input of the integrator. C) The square-wave output of the integrator has led to this oscillator being considered a function generator. D) The comparator has a single trip point. 10) Which of the following is true about a Wien-bridge oscillator? A) The feedback loop will have a gain equal to one when the closed-loop gain is three. B) A steady pulse is the output of a Wien-bridge oscillator. C) A voltage divider is present in the positive feedback loop, and a lead-lag circuit in the negative feedback loop. D) The phase shift through the circuit is 180o when the frequency is equal to the resonant frequency.
4
10)
Figure 19-8 11) In Figure 19-8, R1 = 35 k▲, R2 = 75 k▲, R3 = 17 k▲, R4 = 16 k▲, C1 = 0.03 µF, C2 = 0.03 µF, C3 = 0.02 µF, and C4 = 0.006 µF. Calculate the critical frequency of the high-pass filter. A) 280.5 Hz
B) 103.55 Hz
C) 360.75 Hz
11)
D) 234.65 Hz
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 12) In an integrator formed by using an op-amp with an RC circuit, the capacitor's charging current is constant.
12)
13) For a Wien-bridge oscillator to start, the initial closed-loop gain of the amplifier must be less than three.
13)
14) A comparator used to detect a particular reference voltage will have an output signal of
14)
-Vout(max) whenever the input is below the reference voltage. 15) The closed-loop gain in a Wien-bridge oscillator should be 3, so that the gain around the loop is 1.
15)
16) In a basic shunt regulator, the control element is connected in series with the load.
16)
17) The attenuation of the lead-lag circuit used in a Wien-bridge oscillator is 1/6.
17)
18) Faster comparators are well-suited for battery-powered applications.
18)
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Answer Key Testname: CH 19
1) C 2) B 3) D 4) C 5) D 6) B 7) D 8) C 9) A 10) A 11) B 12) TRUE 13) FALSE 14) TRUE 15) TRUE 16) FALSE 17) FALSE 18) FALSE
6
Chapter 20: Special-Purpose Op-Amp Circuits MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) In an OTA, the bias current can be controlled by . A) using a variable resistor in series with the input B) using a capacitor in series with the inverting terminal C) connecting a capacitor between the noninverting input terminal and ground D) connecting a variable resistor in series with the bias resistor
1)
Figure 20-3 2) For the circuit in Figure 20-3, if R1 = R2 = 40 k▲, RG = 125 ▲, Vin1 = 20 V, and Vin2 = 7 V, calculate Vout2 — Vout1. A) 3925 V
B) 8333 V
C) 3210 V
1
D) 6739 V
2)
Figure 20-4 3) In Figure 20-4, the input is 50 mV peak-to-peak, 1MHz sine wave. The modulation voltage is a +15 V to +3 V, 1kHz sine wave. The supply voltage is +11 V and -11 V. If RBIAS = 62 k▲, RL = 9 k▲, and K = 16 µS/µA, find IBIAS(max). A) 1089.28 µA
B) 456.57 µA
C) 396.78 µA
3)
D) 2733.34 µA
4) Which of the following is true about current sources? A) A voltage-to-current converter uses a variable resistor to vary the output current even if the input voltage is constant. B) A current-to-voltage converter provides a load current that remains constant when the input voltage changes. C) A constant-current source provides a constant load current despite changes in the input voltage. D) A current-to-voltage converter converts a variable input current to a proportional output voltage.
4)
5) Which of the following is true of a basic (passive) diode clamper? A) The capacitor charges to its peak value. B) The voltage added to the input signal is equal to the voltage drop across the diode. C) The diode direction decides whether the input voltage is increased or decreased. D) A clamper superposes an ac voltage on the input signal.
5)
2
Figure 20-3 6) For the circuit in Figure 20-3, what value of the gain-setting resistor will produce a gain of 500, given that R1 = R2 =47 k▲ ? A) 124.81 ▲
B) 275.37 ▲
C) 212.59 ▲
6)
D) 188.38 ▲
7) Which of the following is true of a basic instrumentation amplifier? A) The external resistor can be chosen by calculating the desired voltage gain. B) The common-mode voltage is applied to the inverting inputs of the op-amps A1 and A2. C) The input is connected to the noninverting terminals of the op-amps A1 and A2. D) The inverting inputs of op-amps A1 and A2 receive a portion of the feedback from only their own respective outputs.
7)
8) Which of the following is true of an active clamping circuit? A) The output signal's minimum is determined by the voltage drop across the diode. B) The capacitor adds or subtracts by a voltage equal to the input signal's amplitude. C) The output signal's minimum is 0 V. D) The capacitor charges to the peak of the input voltage minus the voltage drop across the diode.
8)
3
Figure 20-3 9) For the circuit shown in Figure 20-3, if the common-mode voltages are equal, find the differential output for R1 = 30 k▲, R2 = 32 k▲, RG = 90 ▲, Vin1 = 12 V, and Vin2 = 7 V. A) 900.25 V
B) 7258.7 V
C) 1581.3 V
9)
D) 3449.4 V
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 10) In an operational transconductance amplifier (OTA), the voltage gain can be controlled by adjusting the bias current.
10)
11) A clipper gives zero output voltage when the input voltage is beyond the specified level.
11)
12) In an isolation amplifier, modulation allows the information in the first signal to be present in the second as well.
12)
13) In an operational transconductance amplifier (OTA), the output voltage equals gain times the input voltage.
13)
14) For an instrumentation amplifier with RG=(100k▲)/(Av-1), an e xternal resistor is required for
14)
unity gain.
4
Answer Key Testname: CH 20
1) D 2) B 3) C 4) D 5) C 6) D 7) A 8) B 9) D 10) TRUE 11) FALSE 12) TRUE 13) FALSE 14) FALSE
5
Chapter 21: Measurement, Conversion, and Control MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Which of the following is true of analog-to-digital conversion? A) The theoretical minimum limit of the sampling rate is known as the Nyquist rate. B) Lower bit analog-to-digital converters (ADC) have a higher resolution than higher bit ADCs. C) The conversion of an analog voltage into a digital quantity occurs instantaneously. D) Quantization error is the inherent inaccuracy in representing an analog voltage as a digital one.
1)
2) Which of the following is true of displacement transducers? A) When the magnetic core of a LVDT is centered, the voltage induced in each secondary is equal. B) Hysteresis is preferred in contacting displacement transducers. C) The major advantage of fiber-optic sensors is their dynamic range. D) A linear variable differential transformer (LVDT) has poor repeatability due to the movement of its magnetic core.
2)
3) When a resistance temperature detector (RTD) is connected in a 3-wire bridge, the resistance of the third wire, from the RTD to VOUT, has no effect. This is because . A) a low-resistance wire is used B) no current goes through it C) the output terminals of the bridge are connected across a low impedance D) it is compensated by the length of the wire from R3 to the RTD
3)
4) Which of these devices is the most sensitive to temperature change? A) resistance temperature detector B) thermocouple C) thermistor D) resistor
4)
5) Which of the following devices works on the principle of resistive change with temperature? A) zener-based IC precision temperature sensor B) thermocouple C) varactor diode D) thermistor
5)
6) Gage pressure transducers . A) have no input arrows in their symbol B) measure applied pressure relative to the ambient pressure C) measure one applied pressure relative to another applied pressure D) have two input arrows in their symbol
6)
7) Which of the following is true of sample-and-hold circuits? A) Aperture jitter is the time for the analog switch to fully open after the control voltage switches to hold level. B) A low impedance output amplifier prevents the capacitor from discharging quickly. C) The output of a sample-and-hold circuit is a square wave. D) The output follows the input when the control voltage is low.
7)
1
8) An AC tachometer is an example of a(n) A) linear velocity transducer C) angular velocity transducer
.
8) B) noncontacting displacement transducer D) contacting displacement transducer
9) Which of the following is true about thermocouples? A) The junction created at the point where the thermocouple wires connect to the circuit terminals is called cold junction. B) The voltage produced across the junction of thermocouple wires and circuit terminals is called Seebeck voltage. C) The voltage versus temperature characteristic of thermocouples is linear. D) The voltage produced in a thermocouple depends primarily on the cross-sectional area of the metals at the junction.
9)
10) Which of the following is true of a silicon-controlled rectifier (SCR)? A) SCRs are normally operated in the reverse-avalanche region. B) If the forward breakover voltage is exceeded, the SCR will be in the forward-conduction region. C) A positive pulse of current on the gate increases the forward-breakover voltage. D) An SCR that has been turned on and connected to an ac circuit will remain on.
10)
11) Which of the following is true about acceleration transducers? A) The seismic mass moves because of the force applied to it through the spring. B) Piezoelectric crystals have a very high output. C) The relative motion between the seismic mass and the ground is proportional to the acceleration of the transducer. D) Accelerometers used to measure vibration should be used at frequencies greater than their natural frequency.
11)
12) A copper/constantan thermocouple is used to measure the temperature in an industrial temperature chamber. The junction between the two wires is placed in the temperature chamber. The other ends of the two wires are connected to a copper circuit board present outside the chamber. Which of the following is true about this scenario? A) A reference thermocouple held at a constant known temperature can be used to eliminate any unwanted thermocouples. B) The junction between the constantan wire and the copper circuit board will increase the thermocouple voltage. C) Two cold junctions are formed, one at each connection between a wire and the circuit board. D) The temperature-sensor in a cold-junction compensator should be kept at the same temperature as the thermocouple junction.
12)
13) Which of the following is true of thermistors? A) They are more expensive than resistance temperature detectors. B) Their change in resistance per degree change in temperature is lower than other temperature dependent devices. C) The resistance of thermistors increases with increase in temperature. D) Their temperature characteristic is highly nonlinear.
13)
2
14) Which of the is true of differences between thermistors and resistance temperature detectors (RTDs)? A) Thermistors have greater sensitivity to temperature changes than RTDs. B) Resistance change is inversely related to temperature change in RTDs, but it is directly related in the case of thermistors. C) RTDs cost less than thermistors. D) The temperature characteristic of thermistors is more linear than that of RTDs.
14)
15) Which of the following is true of pressure-measuring circuits? A) When the diaphragm of a pressure gage expands, the resistance increases. B) The flow rate of a fluid is inversely proportional to the measured differential pressure. C) They use resistance temperature detectors to measure differences in pressure. D) They can only measure pressure variation with respect to vacuum.
15)
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 16) Gate triggering is the method generally used to turn on a triac.
16)
17) When a resistance temperature detector is connected in a bridge circuit, the resistors in the bridge are chosen such that the bridge is balanced at only a particular temperature.
17)
18) Radio frequency interference is generated when a zero-voltage switch is used to turn on an SCR.
18)
19) Gage factor of a strain gage is the ratio of the fractional change in resistance to the fractional change in length along the axis of the gage.
19)
20) Generally, in analog-to-digital conversion, 2n comparators are required for conversion to an n-bit binary code.
20)
21) A triac is a thyristor with the ability to pass current bidirectionally.
21)
3
Answer Key Testname: CH 21
1) A 2) A 3) B 4) C 5) D 6) B 7) C 8) C 9) A 10) B 11) A 12) A 13) D 14) A 15) A 16) TRUE 17) TRUE 18) FALSE 19) TRUE 20) FALSE 21) TRUE
4