What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
CS 21 - Computer Organization and Assembly Language Programming Lecture 7 Introduction to Electrical Devices and Circuits University of the Philippines - Diliman College of Engineering Department of Computer Science
What is Electricity?
Fundamental Quantities
Ohm’s Law
Outline
1
What is Electricity?
2
Fundamental Quantities
3
Ohm’s Law
4
Series and Parallel Interconnection
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Outline
1
What is Electricity?
2
Fundamental Quantities
3
Ohm’s Law
4
Series and Parallel Interconnection
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Electricity Defined
Electricity has two common meanings: (1) Energy that causes ”things” to turn on (2) Flowing motion of electric charges
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Electricity Defined
Electricity has two common meanings: (1) Energy that causes ”things” to turn on (2) Flowing motion of electric charges
Trivia: Dagitab is the Filipino term for electricity
What is Electricity?
Fundamental Quantities
Ohm’s Law
Outline
1
What is Electricity?
2
Fundamental Quantities
3
Ohm’s Law
4
Series and Parallel Interconnection
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Fundamental Electrical Quantities
Charge Current Voltage Resistance Power
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Charge
Basic physics: two types of charges - positive and negative
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Charge
Basic physics: two types of charges - positive and negative Positive: protons Negative: electrons
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Charge
Basic physics: two types of charges - positive and negative Positive: protons Negative: electrons In this class: only electron flow is relevant
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Charge
Basic physics: two types of charges - positive and negative Positive: protons Negative: electrons In this class: only electron flow is relevant Unit of measurement: Coulombs (C)
What is Electricity?
Fundamental Quantities
Ohm’s Law
Current Flow of charges or ”charges in motion”
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Current Flow of charges or ”charges in motion” ”Kuryente”
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Current Flow of charges or ”charges in motion” ”Kuryente”
Unit of measurement: Amperes (A) 1A = 1C/s how many charged particles pass through per second
What is Electricity?
Fundamental Quantities
Ohm’s Law
Voltage
Energy required to ”push charges”
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Voltage
Energy required to ”push charges” Also known as potential difference
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Voltage
Energy required to ”push charges” Also known as potential difference Unit of measurement: Volts (V) 1V = 1J/C how much energy is spent to push an electron
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Resistance
Opposition to the current
Ohm’s Law
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Resistance
Opposition to the current ”Degree of hardship”
Ohm’s Law
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Resistance
Opposition to the current ”Degree of hardship” Unit of measurement: Ohms (Ω) 1Ω = 1V/A remember, resistance is inversely proportional to current
What is Electricity?
Fundamental Quantities
Ohm’s Law
Power
Rate at which energy is expended
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Power
Rate at which energy is expended Unit of measurement: Watts (W) 1W = 1VA energy in terms of V, rate in terms of A
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Power
Rate at which energy is expended Unit of measurement: Watts (W) 1W = 1VA energy in terms of V, rate in terms of A 1W = 1VA = 1 (J/C) (C/s)
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Power
Rate at which energy is expended Unit of measurement: Watts (W) 1W = 1VA energy in terms of V, rate in terms of A 1W = 1VA = 1 (J/C) (C/s) 1W = 1VA = 1 (J/s)
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Types of Circuits and Circuit Elements
Circuit elements can be classified according to the relationship of the current through the element to the voltage across the element.
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Types of Circuits and Circuit Elements
Circuit elements can be classified according to the relationship of the current through the element to the voltage across the element. Resistor - voltage across is directly proportional to the current
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Types of Circuits and Circuit Elements
Circuit elements can be classified according to the relationship of the current through the element to the voltage across the element. Resistor - voltage across is directly proportional to the current Independent sources - voltage is completely independent of current, and vice versa
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Types of Circuits and Circuit Elements
Circuit elements can be classified according to the relationship of the current through the element to the voltage across the element. Resistor - voltage across is directly proportional to the current Independent sources - voltage is completely independent of current, and vice versa Dependent or controlled sources - source voltage or current depends upon a current or voltage elsewhere
What is Electricity?
Symbols
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Convention
In volt source (battery symbol), the longer leg is positive
What is Electricity?
Fundamental Quantities
Ohm’s Law
Convention
Current flows from the positive side
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Convention
The receiving side of any passive element is positive
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Convention
Note: each element should have the plus-minus pair
What is Electricity?
Fundamental Quantities
Ohm’s Law
Outline
1
What is Electricity?
2
Fundamental Quantities
3
Ohm’s Law
4
Series and Parallel Interconnection
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Important Concept The flow of current always encounters some resistance, resulting in a voltage drop and the conversion of electric energy to heat.
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Ohm’s Law
Ohm’s Law shows the relationship between current, voltage and resistance in an electrical network V=IR Where V = voltage I = current R = resistance
What is Electricity?
Fundamental Quantities
Ohm’s Law
Outline
1
What is Electricity?
2
Fundamental Quantities
3
Ohm’s Law
4
Series and Parallel Interconnection
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Series Connection
series - one node of an element is a connected to a node of another
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Parallel Connection
parallel - two or more elements share the same nodes
What is Electricity?
Fundamental Quantities
Resistor Equivalences
Ohm’s Law
Series and Parallel Interconnection
What is Electricity?
Example 1
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
What is Electricity?
Example 2
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Example 3 What is the equivalent resistance value of this network?
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Things to remember
Elements in series have the same current running through them Elements in parallel have the same voltage across them
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Things to remember
Elements in series have the same current running through them Elements in parallel have the same voltage across them Wires have zero resistance (for simplicity)
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
Things to remember
Elements in series have the same current running through them Elements in parallel have the same voltage across them Wires have zero resistance (for simplicity) Follow the voltage-current convention
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
More Examples
Find the resistance of the equivalent resistor.
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
More Examples
Find the resistance of the equivalent resistor.
What is Electricity?
Fundamental Quantities
Ohm’s Law
Series and Parallel Interconnection
More Examples
Find the resistance of the equivalent resistor.
What is Electricity?
Fundamental Quantities
Ohm’s Law
So...
Any questions?
Series and Parallel Interconnection