.
G
. tr re -2 c o 3 le Edit -107 E i 92 t ge isin 8-2
i gg
Ro
l
ca
i on
-J
t’s Trev 78-8 9
Le
BN
Questo volume, sprovvisto del talloncino a lato, è da considerarsi copia di saggio-campione gratuito, fuori commercio (vendita e altri atti di disposizione vietati: art. 17, c. 2 L. 633/1941). Esente da I.V.A. (D.P.R. 2610-1972, n. 633, art. 2, lett. d). Esente da Documento di Trasporto (D.P.R. 14-08-1996, n. 472).
Giuseppe Roggi - John Picking
Let’s get
Electronical
Let’s get Electronical
IS
Giuseppe Roggi - John Picking
ng
ki
c Pi
Questo volume è corredato di un CD: volume e CD non possono essere venduti separatamente.
Let_s Electronical.indd 1-3
22,90
9
788829 210732
Trevisini Editore
ISBN 978-88-292-1073-2
Trevisini Editore
08/02/12 09.28
Giuseppe Roggi - John Picking
Let’s get
Electronical
Trevisini Editore
[stampa]001_009_apertura.indd 1
07/02/12 09.18
Presentazione Caratteristiche Generali LET’S GET ELECTRONICAL è un corso specialistico di lingua inglese destinato agli studenti degli istituti tecnici e professionali per il settore elettrico ed elettronico. A chi s’indirizza – Istituti Tecnici Industriali di Stato – Istituti Professionali di Stato Obiettivi Metodologici Utilizzare in modo corretto la lingua inglese nel vario mondo tecnologico. Soddisfare i bisogni comunicativi professionali dei futuri operatori del settore. Acquisire le nozioni teoriche fondamentali e le capacità operative adeguate mediante lo sviluppo parallelo e integrato delle quattro abilità linguistiche. Fornire una preparazione equivalente ai livelli B1 - B2 del Framework europeo. Struttura del Testo Lo Student’s Book è diviso in dodici unità: UNIT 1 UNIT 2 UNIT 3 UNIT 4 UNIT 5 UNIT 6 UNIT 7 UNIT 8 UNIT 9 UNIT 10 UNIT 11 UNIT 12 APPENDIX
Switch on the Electric Power Magnetism and Electricity (1) Magnetism and Electricity (2) Magnetism and Electricity (3) Electronics (1) Electronics (2) Electronics (3) Electronics (4) Telecommunication (1) Telecommunication (2) Computer Technology (1) Computer Technology (2) Applying for a Job
Terza Prova Mock Exam è pensato per la preparazione specifica e autonoma alla terza prova scritta dell’Esame di Stato. Compact Disc Al testo è allegato un compact disc per aiutare gli studenti a migliorare la comprensione e la pronuncia. Il CD riporta tutti i dialoghi ed i tapescript proposti per le attività di ascolto. Guida per l’Insegnante Il Teacher’s Book contiene le soluzioni di tutte le attività e i testi delle registrazioni del CD. Per facilitare il lavoro di valutazione dell’insegnante vengono proposte otto verifiche da somministrare agli studenti. Nella Guida sono fornite anche le relative soluzioni delle verifiche. ONLINE offre materiale extra da scaricare dal sito www. trevisini.it
[stampa]001_009_apertura.indd 3
07/02/12 09.18
Table of Contents Unit 1 page 10
Unit 2 page 32
Unit 3 page 54
Unit 4 page 82
Unit 5 page 108
Unit 6 page 132
[stampa]001_009_apertura.indd 4
Switch on the Electric Power!
Facts 1 Discoveries 2 Electricity in the Nineteenth Century 3 What Is Electricity? 4 Static Electricity
Magnetism and Electricity (1)
1 What Is An Electric Current? 2 Measurement of Electric Current 3 Electric Conductors and Insulators 4 Magnetism
Magnetism and Electricity (2)
1 Chemical Effects of Electric Current 2 Batteries 3 Producing Electricity 4 Transmitting Electricity 5 Inductance, Capacitance, Impedance
Magnetism and Electricity (3)
1 Electrical Circuits 2 DC Current, AC Current 3 Transformers, Rectifiers and Converters 4 Switches, Relays and Commutators 5 Electric Motors and DC Generators
Electronics (1)
1 The Birth of Electronics 2 Conductors and Superconductors 3 Semiconductors 4 Semiconductor Devices
Electronics (2)
1 Electronic Control Systems 2 Recognising Resistors 3 Electronic Circuits 4 Meters
07/02/12 09.18
Information transfer
Grammar
Sounds Good!
Workshop
1
Verb to be Verb to have The Simple Present Articles
Pronunciation of TH The Third Person of the Simple Present
Ways of Creating Static Electricity
Unit 1
Mathematical Signs
The Present Continuous Possessive adjectives and pronouns
Vowel sounds and spelling The letter O The /ə/ and /æ/ sounds
Experiments in Magnetism
Unit 2
Conversion Tables Geometrical Figures and Shapes
The Past Simple Between, Among, In
Past Tense -ed Endings
How to Make an Electromagnet
Unit 3
Simple Arithmetical Operations
The Present Perfect Past Participle -ed Endings Plural Nouns
Diphthongs Pronuncing /i/ and /iː/
Soldering
Unit 4
Symbols for Electronic Components
The Passive Form Through, Across, Over, Along
The letter U The letters OU The letters I and Y
Christmas Tree Fairy Lights
Unit 5
Future Tenses On, Above, Over
Same pronunciation, different spelling, different meaning Pronunciation of SC
Measuring a Resistor
Unit 6
Numbers
Symbols and Formulae in Electronics
[stampa]001_009_apertura.indd 5
07/02/12 09.18
Table of Contents Unit 7 page 156
Unit 8 page 184
Unit 9 page 210
Unit 10 page 236
Unit 11 page 264
Unit 12 page 294 page 322
[stampa]001_009_apertura.indd 6
Facts
Electronics (3)
1 Resistor and Potential Dividers 2 Capacitors 3 Inductors 4 More About Transistors 5 Transducers
Electronics (4)
1 Analogue and Digital Systems 2 Switching Circuits 3 Logic Gates 4 Decision-making Circuits 5 Memory-type Circuits
Telecommunications (1)
1 The Electromagnetic Spectrum and Radio Waves 2 Audio Frequency Amplifiers 3 Radio Transmitters and Receivers 4 Playing and Recording
Telecommunications (2)
1 Colour Television 2 New Television 3 Communication Systems 4 Optical Fibre Communication Systems 5 Radar and Satellites
Computer Technology (1)
1 Introduction to Computers 2 Inside the Computer 3 Computer Memories 4 Computer Peripherals 5 Multimedia
Computer Technology (2)
1 Computer Programming 2 Computer Networks and the Internet 3 Computer Interfacing 4 R emote Controls, Servo Systems and Stepping Motors 5 Robots
Appendix: Applying for a Job
07/02/12 09.18
Information transfer
Grammar
Sounds Good!
Workshop
2
Recognising Capacitors
Quantities Under, Below
Pronunciation of /tʃ/ and /ʃ/ Silent Letters
Resistors in Series and Parallel
Unit 7
Binary Arithmetic and Various Bases Boolean Algebra
The Past Continuous The Present Perfect Continuous Either, Neither, Both, Whether
Pronunciation of -EA-
Testing an Integrated Circuit
Unit 8
—
Comparatives and Superlatives The Imperative
Pronouncing Nouns and Verbs
Building a Simple Medium Wave Receiver
Unit 9
Graphs
Relative Clauses and Pronouns
Consonant Clusters The /ks/ sound The /k/ and /s/ sound
Building a Simple Electronic Organ
Unit 10
Larger and Small Units
Modal and Semi-Modal Verbs -ing Form vs. Infinitive Form
Pronouncing the /ɔː/ and the /ʌ/ Sounds Intonation of Question Tags
A Simple Memory Cell
Unit 11
Secret Codes in Computing
The Conditional Form
Pronouncing the letter E The /ɜ/ sound
A Perfectly Functioning Computer Using Only Free Software
Unit 12
[stampa]001_009_apertura.indd 7
07/02/12 09.18
Unit 5Electronics (1) Facts
Sounds Good!
1 The Birth of Electronics 2 Conductors and Superconductors 3 Semiconductors 4 Semiconductor Devices
Information transfer
The letter U The letters OU The letters I and Y
Symbols for Electronic Components
Grammar Close-Up The Passive Form
Workshop
Christmas Tree Fairy Lights
Grammar window
Through, Across, Over, Along
1. state if the materials below are conductors (c) semiconductors (sc) or insulators (in).
Start Up
[stampa]108_131_unit05.indd 108
A. …………………
B. …………………
C. …………………
D. …………………
E. …………………
F. …………………
G. …………………
H. …………………
I. …………………
J. …………………
K. …………………
L. …………………
07/02/12 09.49
Electronics (1) unit
9
Fact 1
5
109
The Birth of Eletronics The word electronics derives from electrons, negatively charged particles which orbit around the nucleus in the atom. When these electrons flow along a conductor such as wire, the energy flow is called electricity. Electronics deals with the emission of electrons from other forms of conductors and their manipulation in various electronic devices. Electronics begins with the invention of the thermionic valve. The German Heirich Geissler (1814-1879) experimented with electric currents passing through a glass tube from which he had removed the air. The tube glowed with various colours. In the 1880’s the American inventor Thomas Edison (1847-1931) performed an experiment fixing a small metal plate inside the bulb near the carbon filament. When the plate was positively charged, a current flowed towards it from the filament creating a blue light. Edison had invented what was later to be called the thermionic valve. In 1895 the German physicist Wilhelm K. Roentgen discovered X rays and the French scientist Jean B. Perrin demonstrated that the current flowing through a vacuum tube is made up of particles with a negative charge. In 1904 a British scientist, John A. Fleming built a vacuum diode tube that could detect radio signals. This tube, called the Fleming valve, permitted current to pass in one direction only. The American physicist Robert A. Millikan was the first to make accurate measurements of the electrons’ charge. This work enabled scientists to build devices which could control the electrons and make them operate to perform various tasks. Big steps forward in electronics were made between 1907 and 1926 with the development of various vacuum tubes such as the diode, triode, tetrode and pentode. In derive (to): derivare orbit (to): orbitare the 1920’s the American scientist Vladimir K. Zworykin, glass tube: tubo di vetro invented the iconoscope television camera and the glow (to): brillare kinescope television tube. Many more developments fixing: fissando followed. Important discoveries were the magnetron vacuum tube: valvola elettronica which led to microwave radar. The first electronic detect (to): rivelare steps: passi computer was built in 1946 by the two Americans John follow (to): seguire W. Mauchly and John P. Eckert.
2. say whether the following statements are true () or false ()
A. Electronics begins with the invention of the thermionic valve.
B. Thomas Edison invented the electric light bulb. C. The German physicist K. Roentgen discovered the thermionic valve. D. The first electronic computer was built in 1966. E. The American scientist K. Zworykin invented the iconoscope
television camera. F. A. Fleming built a tube called the Fleming valve.
[stampa]108_131_unit05.indd 109
07/02/12 09.49
110
5unit Electronics (1) Symbols for Electronic Components Information transfer
+
1
2
Ammeter
LED (Light Emitting Diode)
AND gate
Microphone
Battery
NAND gate NOR Gate
Bridge Capacitor
Operation Amplifier (Op-Amp)
Capacitor (Electrolytic)
OR Gate
Cell
Photocell
Cross-Wire (Not Joining) Diode
Photodiode
Exclusive NOR gate Exclusive OR gate
Phototransistor
JFET N-channel
Resistor Resistor
JFET P-channel
Speaker Switch or interruptor
MOSFET N-channel
2-way Switch or deviator 1 T1 5
MOSFET P-channel
4
8
Transformer
Ground/Earth - Ground
Transistor (npn)
Inductance coil
Transistor (npn)
Joined wires
+
Lamp
Voltmeter Variable Resistor
LDR (Light Dependant Resistor)
Variable Resistor
3. study the table above and then draw the symbols for the following components. A. resistor
D. transformer
G. transistor (npn)
u05_p110_symbols
[stampa]108_131_unit05.indd 110
B. exclusive OR break
E. photocell
H. photodiode
C. light dependant transistor
F. speaker
I. bridge
07/02/12 09.49
Electronics (1) unit
10
Fact 2
5
111
Conductors and Superconductors A conductor is a material which allows the free flow of electrons, that is, an electric current or heat to pass through it. For example, copper is an excellent conductor and for this reason it is used in electrical cables. All materials can be classified according to their conductivity. They A copper coil. may be divided into three groups: conductors, semiconductors and insulators. Conductors make it easy for a current to pass through them. They have many free electrons. Most metals are good conductors but some metals are not very good. Germanium is an example of a metal which is a poor conductor. Some non-metals such as carbon are also good conductors. A conductor may also be a liquid such as salt water. Superconductors are conductors which offer no resistance to the passage of a current. Many metals become superconductors when they are cooled to very low temperatures near to absolute zero, i.e. −273 °C or 0 Kelvin. Their molecules become immobile and this allows electrons to move through them without colliding and therefore there is no energy loss. The Dutch physicist Heike Kamerlingh-Onnes discovered superconductivity in 1911. Liquid helium was produced by lowering helium gas to a temperature of 4.2 K. A allow (to): permettere metallic alloy was immersed in this liquid and sealed in cables: cavi easy: facile an insulated container. Later scientists managed to raise colliding: collidere, scontrarsi the temperature to 23 K. Karl Müller, a Swiss researcher, loss: perdita made an important discovery in 1983. He used metallic lowering: abbassando oxides called ceramics which are different from metallic alloy: lega alloys in the way they do not lose their superconductivity sealed: sigillata insulated: isolato when currents pass through them to create magnetic fields.
4. Fill in the blanks with the missing words. A. Copper is an excellent ………………………………… and for this reason it is used in ………………………………… cables. B. All materials can be classified according to their ………………………………… C. Conductors have many ………………………………… electrons. D. Copper and platinum do not become ……………………………… when the temperature is lowered. E. The non-metal ………………………………… is a good conductor.
[stampa]108_131_unit05.indd 111
07/02/12 09.49
112
5unit Electronics (1) The Passive Form Grammar close-up
In the active form the subject of the verb is the person or thing doing the action. The fire destroyed Fred’s garage. The above sentence is about the fire, and says what it did. (The fire is the ‘agent’.) In the passive form the object or person receiving the action becomes the subject. Fred’s garage was destroyed by the fire. The above sentence is about Fred’s garage, and says what happened to it. • A passive sentence is usually more formal than an active one. • In an active sentence the agent is named. • In a passive sentence the agent can be left out. Without the agent
Example
The agent was previously mentioned.
The managing director presented the research report to the press. Many questions were asked about the new machinery.
The agent is unknown.
My digital camera has been stolen.
The agent is obvious.
Two terrorists were arrested at the airport.
The agent is unimportant.
The rubbish bins are emptied early every morning.
The writer/speaker does not want to name the agent.
A mistake was made when measuring the V.I. of the oil.
With the agent
Example
To name the author of a given work.
A new form of algebra was devised by George Boole.
To give some information about the type of agent.
City mail is often delivered by private messengers.
To show that the agent is inanimate or abstract.
General laws of gravity were formulated by scientific observation.
The Passive Form is used: • when we want to give more importance to the person or thing receiving the action Two labourers were hurt by the falling load. The steam engine was perfected by Stevenson. • in scientific and technical descriptions, announcements and reports The gantries are powered by electric motors. Components have been drastically reduced in size in recent years. • for orders, instructions and prohibitions Soldering irons must be cleaned after use. Students are not allowed to smoke in the laboratories. • to translate the Italian impersonal form (Si passivante) International telephone cards are sold here. It is said that Dr Barker is moving to EBM next month. Visits to component manufacturers are arranged during the first year. It is believed that they are building a new prototype. • for doubtful actions in the past: the structure modal + have been + past participle is used Carol may have been given a new job. • also with modal verbs and have to. In this case they are followed by be + past participle. The director must be notified immediately of any changes. Hard discs can be bought separately.
[stampa]108_131_unit05.indd 112
07/02/12 09.49
Electronics (1) unit
5
113
That repair job has to be finished by 3 o’clock. Student cards must be shown when entering the library. • In wh- questions the preposition by is put after the verb. What was the short circuit caused by? • When a verb has two objects, one direct and one indirect, it is possible to have two kinds of passive sentence. Common verbs with two objects: give, ask, promise, tell, offer, pay, show, send, write, lend, sell, etc. active: His parents promised Sean a new DVD player. passive 1: Sean was promised a new DVD player by his parents (more commonly used). passive 2: A new DVD player was promised to Sean by his parents. Form The passive is formed with the verb to be followed by the past participle of the main verb. Tenses
Active voice
Passive voice
PRESENT SIMPLE
starts
is started
PRESENT CONTINUOUS
is starting
is being started
PAST SIMPLE
started
was started
PRESENT PERFECT
has started
has been started
PAST CONTINUOUS
was starting
was being started
PAST PERFECT
had started
had been started
FUTURE
will start
will be started
FUTURE PERFECT
will have start
will have been started
GOING TO
is going to start
is going to be started
PRESENT CONDITIONAL
would start
would be started
PAST CONDITIONAL
would have started
would have been started
INFINITIVE
to start
to be started
PERFECT INFINITIVE
to have started
to have been started
PRESENT PARTICIPLE
starting
being started
PERFECT PARTICIPLE
having started
having been started
5. change each active verb to the passive. A. to bring
……………………
H. will measure
……………………
B. had drunk
……………………
I. has reduced
……………………
C. must switch off
……………………
J. cleaned
……………………
D. can prevent
……………………
K. will have produced ……………………
E. illuminates
……………………
L. may cause
……………………
F. to have touched
……………………
M.has cooled
……………………
N. are installing
……………………
G. is going to collect ……………………
[stampa]108_131_unit05.indd 113
07/02/12 09.49
114
5unit Electronics (1) Active
Passive
PRESENT SIMPLE The turner cuts the work pieces on the lathe.
ð
The work pieces are cut by the turner on the lathe.
PRESENT CONTINUOUS The students are measuring the hydraulic pressure.
ð
The hydraulic pressure is being measured by the students.
ð
Some flowers were sent to Jean by Mr Miller.
ð
A new cordless mouse has been bought by Brenda.
PAST CONTINUOUS Ken was helping Chris with the wiring.
ð
Chris was being helped by Ken with the wiring.
PAST PERFECT The inspectors had tested the crane.
ð
The crane had been tested by the inspectors.
FUTURE They will check the steel ropes later.
ð
The steel ropes will be checked by them later.
FUTURE PERFECT Joe will have repaired the gearbox in time.
ð
The gearbox will have been repaired in time by Joe.
GOING TO form Jean’s going to decorate the room next week.
ð
The room is going to be decorated by Jean next week.
PRESENT CONDITIONAL If Brenda were here, she would win the contest.
ð
The contest would be won by Brenda if she were here.
PERFECT CONDITIONAL Kay would have invited Ken if he had been more polite.
ð
Ken would have been invited by Kay if he had been more polite.
INFINITIVE Visitors are to show tickets on request.
ð
Tickets are to be shown by visitors on request.
PERFECT INFINITIVE Joseph Bramah is said to have invented the hydraulic press.
ð
The hydraulic press is said to have been invented by Joseph Bramah.
PAST SIMPLE Mr Miller sent Jean some flowers. PRESENT PERFECT Brenda has bought a new cordless mouse.
6. choose words and phrases from each of the three columns to form passive sentences. WORDS
[stampa]108_131_unit05.indd 114
PROCESSES
EXTRA DATA
A. computers
show
by satellite
B. radios
transmit
iron filings
C. conductors
overheat
underground
D. magnets
pick up
at Dixon’s
E. electric cables
lay
at the Tokyo Electronics Fair
F. mobile phones
sell
when the voltage is too high
07/02/12 09.49
Electronics (1) unit
5
115
Through, Across, Over, Along
Grammar window
• Across or Over are used to talk about a position on the other side of something: a road, a river, etc. Mr Bonnington lives in the house across/over the road. • Across is used to talk about something like a surface, an area, a country or sea, etc. The programme was broadcast across Europe. The images moved rapidly across the screen. • Along is used to talk about something like a line of some kind: a road, a river, a wire, etc. The current flows along the cable. Barges were moved along the canal. • Through is used to talk about something like a movement in a three-dimensional space. Carol struggled through the crowd to reach the stage at the rock concert. • Through is often used to express movement from one side to the other. The electrons passed freely through the conductor. Current is the movement of free electrons through a substance. 7. change the active sentence to a passive sentence. A. The manufacturers have reduced the size of their calculators. B. The technicians have removed the mainframe to the lower floor. C. Japanese companies have cut all salaries in the last few months. D. The factory workers wrap the keyboards in bubble wrap. E. They produce many mobile telephones in Japan. F. We have to link the LED to the ignition circuit. G. Employers must pay all expenses for the training course. H. All workers must wear overalls in the assembly plant. 8. Translate into english. A. I vigili del fuoco sono stati già chiamati. B. Molte riviste tecniche si pubblicano mensilmente in America. C. Si possono comprare contraccettivi a qualsiasi ora dai distributori automatici. D. L’inglese si parla quasi dappertutto nel mondo. E. Il museo delle scienze di Londra è visitato da più di un milione di persone ogni anno. 9. complete with across or over. A. Martha drew a line …………… the map. B. Pedro was so short, he couldn’t see …………… the steering wheel. C. The dog ran away from me and disappeared …………… the hill. D. They cycled …………… America from the Pacific to the Atlantic. E. The children’s ball is always coming …………… the fence. 10. circle the correct or most appropriate words in each sentence. A. The fog was so dense, it seemed like walking across/over/along/through smoke. B. He lives just across/over/along/through the frontier in Pakistan. C. The magnetic flux passes across/over/along/through the core. D. A release hole was made across/over/along/through the cover of the tank. E. I saw sheep moving across/over/along/through the country road.
[stampa]108_131_unit05.indd 115
07/02/12 09.49
116
5unit Electronics (1) Semiconductors
Fact 3
A semiconductor is a solid or liquid with a resistivity which is more than that of good conductors but less than that of insulators. Unlike metals for ordinary temperatures they have a negative temperature coefficient of resistance. The conductivity of these materials is easily modified in the presence of even very small amounts of impurities. Examples of materials frequently used as semiconductors are: silicon, silicon carbide, cuprous oxide, lead telluride, gallium oxide, gallium phosphide, lead sulphide, and germanium. There are three main types of semiconductor: defect, extrinsic and intrinsic. Materials used as semiconductors must be very pure to function properly. • Intrinsic semiconductor: conductor whose electrical properties are dependent on its purity. An extrinsic semiconductor is also named “doped semiconductor”. • Defect semiconductor: one containing impurities. • Extrinsic semiconductor: contains impurities calculated to have certain functional characteristics. • Compensated crystalline semiconductor: one in which the presence of an impurity is to some degree neutralised by the presence of another with opposite characteristics of conductivity. An impurity which induces electronic conduction by providing free electrons is called a donor impurity. The opposite kind of impurity is called an acceptor impurity. Doping impurities
In a crystalline semiconductor, this is a minute trace of an added substance whose atoms attract electrons from the atoms in the crystal lattice and so create holes in the main structure. This trace is also called acceptor impurity and gives rise to P-Type Conductivity. For example one part in ten thousand of boron can Tool box increase the conductivity of silicon one million times. P-type Conductivity The same happens when an atom with five electrons is added to (electronics) The conductivity associated with a silicon lattice: every atom added gives a free electron to the main holes in a semiconductor, which are equivalent structure. This trace is also called donor impurity and gives rise to to positive charges. N-type Conductivity. Arsenic is a donor impurity like boron is an Source: answers.com acceptor impurity. For example one part in ten thousand of arsenic increases conductivity of silicon three million times. Compound semiconductors are semiconductors made from a crystalline chemical compound which is a combination of elements from the periodic table as shown below. iiB
more than: più di less than: meno di unlike: a differenza even: persino impurity: impurità to some degree: in una certa misura minute: minuscola trace: traccia essentially: essenzialmente tightly: strettamente
[stampa]108_131_unit05.indd 116
ii
iV
V
Vi
B
C
N
O
Al
Si
P
S
Zn
Ga
Ge
As
Se
Cd
In
Sn
Sb
Te
Hg
Ti
Pb
Bi
Po
Insulators Most solid materials are classified as insulators because they offer very large resistance to the flow of electric current. Metals are classified as conductors because their outer electrons are not tightly bound, but in most materials even the outermost electrons are so tightly bound that there is essentially zero electron flow through them with ordinary voltages. Some materials are particularly good insulators and can be characterized by their high resistivities.
07/02/12 09.49
Electronics (1) unit
5
117
11. are these sentences riGHT (a) or WronG (B). if there is no information to answer, choose doesn’T saY(c). a B c A. Silicon, gallium and germanium are used as semiconductors. B. Donor impurity induces electronic conduction by providing free electrons. C. Semiconductors are very important technologies of the 20th century. D. Compound semiconductors are made from iron and copper. E. The semiconductor industry sells a hundred billion Euros of product per year. F. Good insulators are characterized by high resistivities.
Semiconductor Devices A semiconductor device is an electronic device in which the conduction of electrons mainly takes place in a semiconductor.
Fact 4
Semiconductor Diodes The ideal Diode. It is a two terminal device with the characteristic of an asymmetrical voltage-current and conducts with zero resistance when forward biased and offers an infinite resistance when reverse biased. An ideal diode acts like an automatic switch. The switch is closed when the diode is forward biased and is opened when reverse biased. Semiconductor diodes only allow the current to flow in one direction and are used as rectifiers. There are two types: • p-n Junction Diode. The essential electrical characteristic of a p-n junction is that it constitutes a diode which permits the easy flow of current in one direction but restrains the flow in the opposite direction. A p-n junction is called the semiconductor or crystal diode. A crystal diode is usually represented by the schematic symbol, as shown in figure (a). The arrow in the symbol indicates the direction of easier conventional current flow. Thus the p-n junction, like a thermionic diode, allows unidirectional current flow and can act like a rectifier. A
Ideal diode
B
Ideal diode characteristics
1
arrow head anode
cathode reverse bias
bar
C
V
Switch Analogy closed
open
in forward bias
in reverse bias
• metal-semiconductor point contact. Metal-semiconductor point contact diodes have proved to be good detectors and mixers for radiation from infrared to visible. Until now GaAs, InSb and InP are the most studied and used semiconductor materials for these devices. u05_p117_junction [stampa]108_131_unit05.indd 117
07/02/12 09.49
118
5unit Electronics (1) History In June 1948, a significant breakthrough took place in semiconductor development. This was the discovery of the point-contact transistor. Here at last was a semiconductor that could amplify. This discovery brought the semiconductor back into competition with the electron tube. A year later, junction diodes and transistors were developed. The junction transistor was found superior to the point-contact type in many respects. The junction transistor was more reliable, generated less noise, and had higher powerhandling ability than its point-contact brother. The junction transistor became a rival of the electron tube in many uses. The initial work of Dr. Clarence Melvin Zener led to the development of the Zener diode, which is frequently used today to regulate power supply voltages at precise levels. Then Dr. Leo Esaki, a Japanese scientist, fabricated a diode that could amplify. The device, named the tunnel diode, has amazing gain and fast switching capabilities. Although it is used in conventional amplifying and oscillating circuits, its primary use is in computer logic circuits. Another breakthrough came in the late 1950’s when it was discovered that semiconductor materials could be combined and treated so that they functioned as an entire circuit. Many names have been given to this solid-circuit concept, such as integrated circuits, microelectronics and microcircuitry. Semiconductor Applications Semiconductor devices are all around us. They can be found in just about every commercial product we touch, from the family car to the pocket calculator. Semiconductor devices are contained in television sets, portable radios, stereo equipment, and much more. Science and industry also rely heavily on semiconductor devices. Research laboratories use these devices in all sorts of electronic instruments to perform tests, measurements, and numerous other experimental tasks. Industrial control systems and automatic telephone exchanges also use semiconductors. The various types of modem military equipment are literally loaded with semiconductor devices. Many radars, communication, and airborne equipment are transistorized. Transistors Transistors are very important electronic components. They were invented in 1948 at the Bell Telephone laboratories and are the only semiconductors capable of amplifying an electric current. They are made from semiconductor materials with three or more electrodes that can regulate a current which passes through them. Transistors are usually made up of layers of various semiconductor materials such as silicon which gives them variable electrical properties. Layers may be p-type or n-type. Transistors can be used as oscillators, amplifiers, photocells or switches and have great advantages over thermionic valves. They are very much smaller and consume much less electrical power. They helped to reduce the size of appliances to dimensions a fraction of those needed previously. Billions of them are manufactured each year and they are used profusely in nearly all electronic equipment such as radios, television sets, computers and satellites.
[stampa]108_131_unit05.indd 118
07/02/12 09.49
Electronics (1) unit
5
119
LED LED (Light Emitting Diode) is a semiconductor lamp consisting of very small gallium arsenide diode that produces light with little electric power. They are widely used as indicators beside switches to show that an appliance is switched on or to signal a particular situation, e.g. that the ink cartridge in a printer is empty. Semiconductor Solar Cells Semiconductor solar cells transform solar energy into electrical energy. They consist of slabs of silicon which have a p-n junction near the surface. The sunlight forces electrons out of the atoms of the semiconductor material producing holes and thus causing an electric current to flow. Semiconductor lasers Semiconductor lasers produce narrow beams of intense light. They are efficient lasers, but their light covers a wider frequency range than other types.
biased: polarizzati restrain (to): frenare arrow: freccia infrared: infrarosso breakthrough: passo avanti reliable: affidabile amazing: sorprendente rely on (to): fare affidamento airborne: aerotrasportato made up: formati, composti slabs: piastre beams: raggi
12. say whether the following statements are true () or false ()
A. Semiconductor diodes allow the current to flow in many directions.
B. Junction diodes and transistors were developed in 1949. C. LEDs are used as switches. D. Transistors were invented in 1948. E. Transistors are smaller than thermionic valves. F. Semiconductor lasers transform solar energy into electrical energy.
13. choose the correct word. A. The ideal diode is a one / two terminal device. B. The switch is closed / opened when the diode is forward biased. C. A p-n junction diode permits the stop / flow of current in one direction. D. Metal-semiconductor point contact diodes are bad / good detectors. E. Transistors consume much more / much less electrical power than thermiotic valves. F. Semiconductor lasers produce narrow beams of weak / great light.
[stampa]108_131_unit05.indd 119
07/02/12 09.49
120
5unit Electronics (1) Switch on your Vocabulary! 14. Tick the right answer. 1. Which two adjectives are closest in meaning to narroW?
6. Chose two synonyms for the noun siZe A. length
D. greatness E. amount
A. big
D. large
B. width
B. thin
E. tight
C. range
C. tall
7. Which two verbs are similar
2. Which two verbs are closest in
in meaning to orBiT? A. revolve around
D. run
A. direct
D. control
B. circle
E. walk
B. carry
E. handle
C. stop
meaning to reGulaTe?
C. produce
8. The verb collide means the
3. The past participle modiFied means
same as
A. drawn
D. felt
A. smack
D. kiss
B. allowed
E. calculated
B. dissolve
E. leave
C. altered
C. crash
4. Which of the following words is NOT
9. Choose two synonyms of the adjective
similar in meaning to conTainer?
eFFicienT.
A. knob
D. box
A. useless
D. usual
B. pot
E. case
B. productive
E. futile
C. holder
C. capable
5. All the following adjectives are close in
10. Which are the best two snonyms
meaning to eXcellenT except
for the adjective inTense?
A. marvellous
D. ugly
A. weak
D. powerful
B. fine
E. wonderful
B. tired
E. strong
C. splendid
C. angry
15. Form adjectives from these nouns and vice versa. adJecTiVes
[stampa]108_131_unit05.indd 120
nouns
adJecTiVes
nouns
A. soft
…………………
K. deep
…………………
B. …………………
lightness
L. …………………
width
C. elastic
…………………
M.broad
…………………
D. …………………
strength
N. …………………
weakness
E. flexible
…………………
O. short
…………………
F. …………………
toughness
P. …………………
length
G. hard
…………………
Q. tight
…………………
H. …………………
rigidity
R. …………………
thickness
I. brittle
…………………
S. thin
…………………
J. …………………
resistance
T. …………………
electricity
07/02/12 09.49
Electronics (1) unit
Knowledge
5
121
16. say whether the following statements are true () or false ()
A. A defect semiconductor is a conductor containing impurities.
B. The electrical properties of an extrinsic semiconductor depend on impurities. C. In 1795 K. Roentgen discovered X rays. D. Germanium is a metal which is a poor conductor. E. Transistor layers may be P-type or K-type. F. The physicist Kamerlingh-Onnes discovered superconductivity in 1911. G. A conductor may be a liquid such as salt water. H. A LED is a transistor which reacts to sounds. I. Donor impurity may induce electronic conduction by providing free neutrons. J. Diodes are two-electrode semiconductors with an asymmetrical voltage current.
17 Fill in the blanks with the missing words. A. Semiconductors ………………… narrow beams of intense light. B. LEDs are used as ………………… beside switches. C. ………………… are used in electronic equipment such as radios. D. There are two types of …………………
…………………: point-contact and junction.
E. Acceptor atoms attract electrons creating ………………… F. Aluminium or gallium can create holes by taking away ………………… from the semiconductor. G. ………………… used as semiconductors must be very pure to function properly.
18. complete the paragraph using the words given in the box. - good - glass - few - materials - high - rich
Conductors are 1 ………………… that conduct heat or electricity. A good conductor has a 2 ………………… electrical or heat conductivity, and is a substance such as a metal 3 ………………… in free electrons. A poor conductor, such as the non-metals 4 ………………… and porcelain, has 5 ………………… free electrons. Carbon is exceptional in being non-metallic and yet a relatively 6 ………………… conductor of heat and electricity. 19. answer the questions in your exercise book. A. What did T. Edison fix inside a bulb in the 1880s? B. What does a triode consist of? C. How can materials be classified? D. When do many metals become superconductors? E. What is a semiconductor device? F. What are transistors capable of? G. Name three of the largest users of semiconductor devices. H. State one requirement of an electron tube, which does not exist for semiconductors, that makes the tube less efficient than the semiconductor.
[stampa]108_131_unit05.indd 121
07/02/12 09.49
122
5unit Electronics (1)
20. Tick the right answer. A. A transistor is… 1. an active device which changes the power ration of an electric current 2. an active device with three or more electrodes 3. an active device which reduces the flow of electrons 4. an active device with a power-operated boom 5. an active device which controls the temperature coefficient B. A superconductor is… 1. any material with the property of a steady fall of resistance as its voltage is increased 2. any material with the property of a steady fall of resistance as its current is lowered 3. any material with the property of a steady fall of resistance as its temperature is increased 4. any material with the property of a steady increase of resistance as its temperature is lowered 5. any material with the property of a steady fall of resistance as its temperature is lowered C. Semiconductors are… 1. substances with an electrical conductivity lower than insulators; base material for computer chips and electronic devices 2. substances which are base material for bikes and skaters 3. substances with an electrical conductivity greater than insulators; base material for computer chips and electronic devices 4. substances which are base material for buildings and skyscrapers 5. substances with an electrical conductivity greater than magnets; base material for computer chips D. An insulator is… 1. material or an object that easily allows heat, electricity, light or sound to pass through it 2. a conductor used to obtain an appreciable capacitance 3. a conductor which is connected to the section of a winding 4. material or an object that does not easily allow heat, electricity, light or sound to pass through it. 5. a storage battery, usually with a liquid electrolyte
[stampa]108_131_unit05.indd 122
07/02/12 09.49
Electronics (1) unit
5
123
The letter U Sounds Good!
16
21. in the following list underline the words that have the /ɜ/ sound. use a dictionary if needed. fuel
cut
cushion
urgently
inclusion
pressure
furniture
pudding
butcher
during
turkey
support
surprise
human
luggage
study
sure
curious
22. now listen and check. Then read the words aloud.
The letters OU 23. underline the odd man out. /uː/
soup
though
through
wound
/ɔː/
bought
course
cloud
thought
/aʊ/
flavour
mouth
found
bound
/ʊ/
couldn’t
shouldn’t
shroud
would
/ɔː/
fourteen
flour
pour
yourself
favour
flounder
hour
sour
/ʌ/
courage
tough
touch
journey
/ə/
dangerous
honour
our
various
/aʊə/
The letters I and Y 24. on the lines write /ɪ/, /aɪ/ or /ɜː/ according to the pronunciation of the words. critics
……
first
……
myth
……
wild
……
firm
……
pioneer ……
tyrant
……
third
……
ride
……
windy
……
scientist ……
bird
……
silver
……
lying
……
ridden
……
17
25. now listen and check. Then read the words aloud.
18
26. listen to the sentences in the active form and complete the sentences using the passive form. 1. In the 1880s ………………………………………… by Thomas Edison. 2. In 1985 ………………………………………… by Roentgen 3. In 1904 ………………………………………… by John A. Fleming. 4. In 1911 ………………………………………… by H. Kamerlingh-Onnes. 5. In the 1920s ………………………………………… by Vladimir K. Zworykin. 6. In the 1946 ………………………………………… by J.W. Mauchly and J.P. Eckert. 7. In 1975 ………………………………………… by Bill Gates and Paul Allen.
[stampa]108_131_unit05.indd 123
07/02/12 09.49
124
5unit Electronics (1) Application
27. say whether the following statements are true () or false ()
A. Acceptor atoms repel electrons and create holes.
B. All metals are good conductors. C. Air is not a perfect insulator. D. Copper provides an easy path for an electric current. E. All good conductors are metals. F. Rubber easily releases electrons.
28. match the first half from part a with the correct second half from part B. a
B
A. Conductors make it easy for
1. to create magnetic fields.
A. ...........
B. Most metals are good conductors
2. discovered superconductivity in 1911.
B. ...........
C. Superconductors offer
3. lowering helium gas to a temperature of 4.2 K.
C. ...........
D. H. Kamerlingh-Onnes
4. but some are not very good.
D. ...........
E. Liquid helium was produced by
5. a current to pass through them.
E. ...........
F. In1983 K. Müller used metallic oxides
6. no resistance to the passage of a current.
F. ...........
29. answer the questions in your exercise book. A. What are transistors made from? B. What are the advantages of using transistors? C. What is the function of a semiconductor solar cell? D. What is a compensated crystalline semiconductor? E. What is a donor impurity? F. What is an acceptor impurity? G. What is P-type conductivity?
[stampa]108_131_unit05.indd 124
07/02/12 09.49
Electronics (1) unit
FCE Activity model
5
125
30. Multiple Choice. Choose the answer (A, B, C or D) which best fits each space.
FCE Activity
Transistors
model
Transistors are crucial components in modern electronics, and are considered the most important
1 ………………………… of the modern age. The development
of the transistor grew directly out of 2 ………………………… advances in diode technology during World War II. The first transistor radio was 3 ………………………… in 1954 by Texas Instruments, and by the beginning of the 1960s transistor radios had 4 ………………………… a mainstay of the worldwide electronics market. Also in the 1960s transistors were integrated into silicon chips, showing the way to the 5 ………………………… of personal computers. In 1956, Bill Shockley, Walter Brattain, and John Bardee won the Nobel Prize for physics for their development of the transistor. The primary type of transistor in use is known as a bipolar junction transistor, which 6 ………………………… of three layers of semi-conductor material, two of which have extra electrons, and one which has gaps in it. The two with extra electrons (N-Type) sandwich, the one with gaps (P-Type). This configuration allows the transistor to be a switch, closing and opening rapidly 7 ………………………… an electronic gate, allowing voltage to pass at a determined rate. If a 8 ………………………… transistor is not shielded from light, the light may be used to open or close the gate. The secondary type of transistor is 9 ………………………… as a field-effect transistor, and consists either entirely of N-Type semi-conductive material or P-Type semi-conductive material, with the current controlled by the amount of 10 ………………………… applied to the transistor. 1 2 3 4 5 6 7 8 9 10
[stampa]108_131_unit05.indd 125
A. A. A. A. A. A. A. A. A. A.
day huge given replaced collapse allows some bipolar told voltage
B. B. B. B. B. B. B. B. B. B.
time small suppressed become decline consists all unipolar misunderstood resistance
C. C. C. C. C. C. C. C. C. C.
invention little held changed development excludes or unitary known inductance
D. D. D. D. D. D. D. D. D. D.
loss clear released removed decay ignores like unilateral understood impedance
07/02/12 09.49
126
5unit Electronics (1) Christmas Tree Fairy Lights
Workshop
D2 D1
+12V
D3 D4
R1
D5
1K
D6
100Ω
1K 100Ω Flashing LED LEDs various colours BC547
D7 T1
IN
Circuit A Components R1 R2 D1 D2-D7 T1
R2 O
u05_p126_lights
This is a very simple circuit. It is easy to build and the cost is very low. There are only two resistors, a smallsignal transistor such as a BC547, one ‘flashing’ Led and a chain of normal LEDs. The flashing LED acts as an oscillator and switches the transistor on and off. The transistor switches all the other LEDs. A 12V DC transformer can be used as power source. No current-limiting resistors are needed in the LED chain, because the forward voltages of the Leds in the chain add up to the supply voltage. IF RED leds are used, with a voltage drop of 1.65V each, then 12V will supply seven; alternatively use five yellow (2.1V) each or four green (2.7V). If you calculate the total voltage carefully you can also mix the colours. Circuit B A more complex circuit can be created using two chains as above. By using a PNP transistor by the side of the NPN transistor. The PNP emitter is connected to the 12V+ terminal. The two chains of LEDs will flash alternately.
Application of Electronics Language to language
[stampa]108_131_unit05.indd 126
31. Translate into italian. To-day we are surrounded by innumerable applications of electronics. In the home we have microwave ovens, washing machines and many other pieces of equipment which have a microcomputer controlling temperature, timing, number of operations and so on. Besides radios, televisions, video recorders and stereos we have remote controls which can switch them on and off and search for programmes or time future recordings. We wake in the morning to an electronic alarm and an electronic thermostat programmes the various temperature levels of house heating we require during the day. Our camera has a computer which reads the label on the film we have inserted and calculates the correct aperture and exposure. We open our garage doors and gates with other remote controls and modern cars have a complex series of electronic circuits which check the many mechanical and electrical functions of the vehicle. We take for granted so many of these things but we would find it difficult to return to the days before electronics and to manage without them.
07/02/12 09.49
Electronics (1) unit
5
127
32. Crossword 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
22
21
23
Across 1. Earliest line of communication which used the Morse code. (9) 6. Spanish word for ‘the’ in the masculine gender. (2) 7. First person present simple of verb ‘to be’. (2) 8. Electronic device which converts coded message into understandable language. (7) 10. Chemical formula for calcium. (2) 11. First person object pronoun. (2) 12. Three-electrode valves containing anode, cathode and control grid electrode. (7) 16. The material found in the earth which is later transformed into a pure metal. (3) 17. The first part of a verb in the infinitive. (2) 18. Used to hold cloth before it is sewn or the name of the part of an electric plug which is inserted in a hole of the socket. (3) 19. Inert gas used to fill tubes for lighting. (4) 20. Ninth letter of the Greek alphabet used in English to mean a very small amount or nothing. (4) 22. To break open. A linear gap in a broken surface. (5) 23. A drop of salty water which forms beneath the eye or a verb meaning to rip cloth. (4) Down 1. The first kind of electronic valve. (10) 2. Semiconductor lamp consisting of a very small gallium phosphide diode that produce light with little electric power. (3) 3. Adjective describing all types of equipment using emission of electrons from all forms of conductors other than electric wire. (10) 4. That part of a transmission or circuit which deals with sound. (5) 5. Comparative form of ‘hard’. (6) 9. The most common vehicle on roads. (3) 13. The signal or power line which enters an appliance. (5) 14. Past participle of ‘to do’. (4) 15. A device to detect or measure a physical property. (6) 17. Preposition meaning towards. (2) 18. Verb meaning to place. (3) 21. Preposition used to explain that something is located in a small village or place. (2)
[stampa]108_131_unit05.indd 127
07/02/12 09.49
128
5unit Electronics (1)
Hans Oersted
One of the most distinguished scientific discoverers and physicists of his time, Hans Christian Oersted was born in 1777 at Rudkjobing, where his father was an chemist. In 1794, he entered the University of Copenhagen, where he took the degree of doctor of philosophy in 1799, and soon afterwards became assistant to the professor of medicine. In 1806, after having enjoyed a travelling scholarship for several years, and visited Holland, the greater part of Germany, and Paris, he was appointed extraordinary professor of natural philosophy in the University of Copenhagen. In 1812 he again visited Germany and France, after having published a manual under the title of Videnskaben our Naturen’s Almindelige Love, and Förste Indledning til den Almindelige Naturloere (1811). During his residence at Berlin, he wrote his famous essay on the identity of chemical and electrical forces, in which he first developed the ideas on which were based his great discovery of the intimate connection existing between magnetism and electricity and galvanism. In 1819, he made known these important truths in
[stampa]108_131_unit05.indd 128
a Latin essay, entitled Experimenta circa Efficaciam Conflictus Electrici in acum Magneticam, which he addressed to all the scientific societies and the leading scientists of Europe and America, and thus made good his claim to be regarded as the originator of the new science of electromagnetism. This discovery, which formed one of the most important eras in the history of physical science, obtained for Oersted the Copley Medal from the Royal Society of England, and the principal mathematical prize in the gift of the Institute of Paris. The original and leading idea of this great discovery had been in his mind since 1800, when the discovery of the galvanic battery by Alessandro Volta had first led him to enter upon a course of experiments on the production of galvanic electricity. The enunciation of his theory of electromagnetism was followed by many important experiments in regard to the compression of water, and by numerous other chemical discoveries, among which we may instance his demonstration of the existence of the metal aluminium in alumina. The influence which Oersted exerted on the science of the day by his discoveries, was recognized all over the world, and honours increased upon him with increasing years. Oersted made science popular among all classes. He gave courses of popular scientific lectures to the public, including ladies. Among the works specially written to promote the diffusion of scientific knowledge, those best known are Aanden i Naturen (Copenhagen, 1845), and Natur-loeren’s Mechanische Deel (Copenhagen, 1847), both of which were translated into several
other European languages. The majority of his more important physical and chemical papers are contained in Poggendorff’s Annalen, and were written by him in German or French, both of which he wrote with the same faculty as his own language. At the close of 1850, a national jubilee was held in honour of the 50th anniversary of his connection with the University of Copenhagen—a festival which he did not long survive, as his death occurred at Copenhagen on 9th March 1851. A public funeral, attended by all persons distinguished by rank or learning in the Danish capital, bore testimony to the respect and esteem with which he was regarded by his fellow citizens. He was considered not only as one of the greatest scientific benefactors of his times, but as a man who contributed largely, by his eloquent and earnest advocacy of liberal principles, to the attainment of the high degree of constitutional freedom which Denmark now enjoys. Source: www.nndb.com
Hans Christian Oersted and an assistant at work in his laboratory from an engraving of his times.
07/02/12 09.49
Electronics (1) unit
5
129
33. Now do this mock exam to practice for your Esame di Stato. A. Write about conductiove properties of various materials in not more than 80 words. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… B. Explain in what conditions superconductors function in not more than 40 words. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… C. Write about the importance of semiconductors in electronics in not more than 80 words. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… D. Write about the main semiconductor devices in not more than 60 words. ………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………
[stampa]108_131_unit05.indd 129
07/02/12 09.49
130
5unit Electronics (1)
1. S ay whether the following statements are true () or false () A. A conductor may be a liquid such as salt water. B. A defect semiconductor is a conductor containing impurities. C. Transistor layers may be N-type or Q-type. D. IMPATT, Esaki, LSA and Gunn are conductor diodes. E. Transistors are smaller and consume less power than thermionic valves. F. The electrical properties of an extrinsic semiconductor depend on impurities. G. A LED is an illuminated diode which is used as an indicator. H. Diodes are two-electrode semiconductors with a symmetrical voltage current. I. Donor impurity may induce electronic conduction by providing free protons. J. Edison’s light bulb used a carbon filament.
2. T ick the right answer. A. Conductors have…
1. many free neutrons 2. many free protons 3. many free electrons
B. A few non-metals such as carbon are…
1. bad conductors 2. good conductors 3. poor semiconductors
C. H. Kamerlingh-Onnes discovered superconductivity in…
1. 1911 2. 1921 3. 1931
D. Semiconductor lasers produce narrow beams of…
1. heat 2. light 3. sound
E. Silicon and germanium are used as…
10
marks
8
marks
1. conductors 2. insulators 3. semiconductors
F. A semiconductor containing calculated impurities is called… 1. extrinsic 2. intrinsic 3. defect
G. Transistors were invented in…
1. 1938 2. 1948 3. 1958
H. LED means…
1. Light Extrinsic Device 2. Luminous Emitting Diode 3. Light Emitting Diode
3. F ill the blanks with the missing words.
6
marks
A. ………………… are the only semiconductors capable of amplifying an electric current.
D. Many metals become ………………… when cooled to very low temperature.
B. Semiconductor Solar Cells transform ………………… energy into electrical energy.
E. A ………………… has more resistivity than a good conductor.
C. V. Zworykin invented the ………………… television camera.
F. ………………… conductivity is an enhanced conductivity.
[stampa]108_131_unit05.indd 130
07/02/12 09.49
Electronics (1) unit
131
6
4. Match the word with its correct definition
marks
A. intrinsic semiconductors
1. semiconductors made from a crystalline chemical compound
B. defect semiconductors
2. semiconductors whose electrical properties are those of the pure ideal B. ........... crystal
C. extrinsic semiconductors
3. impurities are neutralized by other impurities withy opposite characteristics
C. ...........
D. compound semiconductors
4. electric conduction in a semiconductor by holes in the valence band
D. ...........
E. crystalline semiconductors
5. a semiconductor whose electrical properties depend on impurities
E. ...........
F. insulators
6. devices having high electrical resistance
F. ...........
A. ...........
10
5.FCE Multiple Choice. Choose the answer (A, B, C or D) which best fits each space. FCE Activity Activity model
5
marks
A model semiconductor is used to 1 …………………… the flow of energy within an electronic setting. These devices are found in many forms and within many types of electronics. Semiconductor devices are comprised of material that can be manipulated easily to 2 …………………… how power reaches an electronic device.
Semiconductors can be 3 …………………… by using an induction of an electric field, exposure to light, pressure and heat. Semiconductor devices are comprised of material with 4 …………………… in it, which are positive, or p-type, and material with extra electrons, which are negative, or n-type. Diodes are some of the most common semiconductor devices 5 …………………… their simple construction. Transistors are more complicated forms of semiconductor devices. These are comprised of several 6 …………………… of p-type and n-type semiconductors. These semiconductor devices allow for more energy to pass through because of their larger size. A MOSFET is the most popular form of semiconductor device because it 7 …………………… the greatest control over conductivity. Its construction includes an electric 8 …………………… that functions as a gate, controlling the flow of power. It is commonly known as a metal gate, but it 9 …………………… no metal. Semiconductor devices are made of a variety of materials. Silicon is the most commonly used material in semiconductor device manufacturing because of its low 10 …………………… and wide temperature range. A. A. A. A. A. A. A. A. A. A.
direct control conserved wires when combinations neglects range expels diet
MARKING GRID
1 2 3 4 5 6 7 8 9 10
[stampa]108_131_unit05.indd 131
B. B. B. B. B. B. B. B. B. B.
show fail altered fans as coils provides paddock contains pay
C. C. C. C. C. C. C. C. C. C.
D. D. D. D. D. D. D. D. D. D.
manipulate flop preserved holes while switches takes field is speed
manifest crash alternated heads because of magnets refuses car excludes cost
excellent!
Very Good!
satisfactory!
unsatisfactory! You must revise.
You need urgent help!
Very poor!
40 or under
34 or under
26 or under
20 or under
16 or under
......
......
......
......
......
07/02/12 09.49