1. BENG1113 PRINCIPLE OF ELECTRICAL AND ELECTRONICS
Chapter 1 (week 1)
FACULTY OF ELECTRONIC AND COMPUTER ENGINEERING

2. Chapter 1: Introduction to Electricity
Learning Outcome
Upon completion of this chapter, student should be able to:
Describe the basic structure of atoms
Define nucleus, proton, neutron and electron
Describe ionization and free electron
Define conductor, semiconductor and insulator
Convert decimal no to standard or engineering notation
Chapter 1: Introduction to Electricity

3. Chapter 1: Introduction to Electricity
Subtopics:
Atomic structure
SI units, Scientific and Engineering notation
Electrical charges
Electrical quantities - voltage, current and resistance
Active and passive components
Basic electrical instruments
Basic circuit measurement
Electrical safety.
Chapter 1: Introduction to Electricity

4. Atomic Structure
ATOM : The smallest particle of an element that possesses the unique characteristics of that element.
PROTON : The basic particle of positive charge.
ELECTRON : The basic particle of negative charge.
NEUTRON : An uncharged particle found in the nucleus of an atom.
NUCLEUS : The central part of an atom containing protons and neutrons.

5. Chapter 1: Introduction to Electricity
Balanced Atom
an equal number of electrons and protons.
no electrical charge.
Chapter 1: Introduction to Electricity

6. Valance Electrons VALANCE SHELL : The outermost shell of an atom.
VALANCE ELECTRONS : Electrons in the valance shell.
The valance electrons contribute to chemical reactions and bonding within the structure of a material and determine its electrical properties.

7. Ionization
Since electrons are lighter than protons and are outside the nucleus, they can be easily moved from atom to atom to form electrons
When an atom absorbs energy, the valance electrons possess more energy and they can actually escape from the outer shell and becoming free electrons.

8. The periodic table

9. Chapter 1: Introduction to Electricity
Exercises
1. How many electrons contains in the valence shell for the elements below.
Sodium
Chlorine
2. Draw the atomic structure of the copper atom (no.of electrons = 29).
Chapter 1: Introduction to Electricity

10. CONDUCTORS A material that easily conduct electrical current.
A CONDUCTOR has 1 to 3 valence electrons in the outermost shell. Therefore its electrons tend to move to other atom.
Most metals are good conductors and the best conductors are single-element materials such as copper, silver, gold and aluminium.

11. INSULATORS
A material that does not conduct electrical current under normal conditions.
Most good insulators are compounds rather than single-element material such as rubber, plastics, glass, mica, and quartz.
An insulator is any material with 5 to 8 valence electrons in the outer ring.

12. SEMICONDUCTORS
A material that is between conductors and insulators in its ability to conduct electrical current. It has exactly 4 valence electrons.
A semiconductor in its pure (intrinsic) state is neither a good nor a good insulator.
The most common single-element semiconductors are silicon, germanium, and carbon.
The most common compound semiconductor is gallium arsenide.

13. SI units [1] length mass time electric current temperature
luminous intensity
amount of substance
meter
kilogram
second
ampere
Kelvin
candela
mole m kg s A K cd
mol
Quantity Unit Symbol
Table 1-1

14. Chapter 1: Introduction to Electricity
This is the units that are derived from the fundamental units except for current since it is a fundamental unit
current
charge
voltage
resistance
power
ampere
coulomb
volt
ohm
watt A C V W
Quantity Unit Symbol
Table 1-2
Chapter 1: Introduction to Electricity

15. Chapter 1: Introduction to Electricity
All magnetic units are derived from the fundamental units [1].
Table 1-3
flux density
magnetic flux
magnetizing force
magnetomotive force
permeability
tesla
weber
ampere-turns/meter
ampere-turn
webers/ampere-turns-meter
ampere-turns/weber T Wb
At/m At
Wb/Atm
At/Wb
reluctance
Quantity Unit Symbol
Chapter 1: Introduction to Electricity

16. Chapter 1: Introduction to Electricity
Scientific notation
Provides a convenient method for expressing large and small numbers
1= /10 =0.1 =10-1
10 = /100 =0.01 =10-2
100 =102 1/1000 = =10-3
1000 =103 1/10,000 = =10-4
Chapter 1: Introduction to Electricity

17. Mathematical Operation
To perform addition or subtraction using powers of ten, the power of ten must be the same for each term:
Multiplication
Division
Power

18. Chapter 1: Introduction to Electricity
Exercises
1. Express each number in scientific notation
200
5000
85000
3,000,000
4750
Chapter 1: Introduction to Electricity

19. Chapter 1: Introduction to Electricity
2. Express each of the following numbers in scientific notation:
0.2
0.005
3. Express each number as a regular decimal number:
1 x 105
2 x 103
3.2 x 10-2
2.5 x 10-6
Chapter 1: Introduction to Electricity

20. Engineering notation Similar to scientific notation
A number can have from one to three digits to the left of the decimal point and the power-of-ten exponent must be a multiple of three [1]
For example;
33000 = 3.3 x 104 = 33 x 103

21. Matrix prefix
Specific powers of ten in engineering notation have been assigned prefixes and symbols [2]
10-3
10-6
10-9
10-12
10-15
milli
micro
nano
pico
femto m n p f
peta
tera
giga
mega
kilo
1015
1012
109
106
103 P T G M k

22. Chapter 1: Introduction to Electricity
Metric unit conversions
Larger unit: move the decimal point to the right
Smaller unit: move the decimal point to the left
e.g.
0.15mA = 150µA
Chapter 1: Introduction to Electricity

23. Chapter 1: Introduction to Electricity
Exercises
1. Perform the mathematical operation; –
(0.0002)( )
(340,000)( )
/0.002
690000/
( )3
( )2
Chapter 1: Introduction to Electricity

24. Chapter 1: Introduction to Electricity
2. Example 1-8 [1]: express the following numbers in engineering notation
82,000
243,000
1,956,000
0.0022
3. Example 1-10 [2]: Convert the following
20 kHz to megahertz
0.01ms to microseconds
0.002km to millimeters
Chapter 1: Introduction to Electricity

25. Chapter 1: Introduction to Electricity
Electrical Charges
Charges of opposite signs (one negative and one positive) attract one another.
Charges of the same sign (both positive and both negative) repulse one another.
Chapter 1: Introduction to Electricity

26. Electrical Charges The unit of charge [1]:
The unit of charge is denoted by Coulomb
One coulomb is the total charge possessed by: x 1018 electrons or protons
A single electron has a charge of 1.6 x C and a single proton has a charge of +1.6 × C.
Total charge;

27. Chapter 1: Introduction to Electricity
Exercises
How many Coulombs of charge do 93.8 x 1016 electron represent?
How many electrons does it take to have 3C of charge?
Chapter 1: Introduction to Electricity

28. Electrical Force Electrical forces act between charges
Q1 and Q2 = charge on the objects (in C)
D = distance between objects (in meters)
k = a constant = 8.99 x 109 N m2/coul2
 The strength of the electrical force decreases as the distance between the charged objects increases

29. Basic Electrical Components and Instuments
Resistors
Resistors resist, or limits, electrical current in a circuit.
Capacitors
Capasitors store electrical charge; they are used to block direct current (dc) and pass alternating current (ac).
Inductors
Inductors, also known as coils, are used to store energy in an electromagnetic field; they serve many useful functions in an electrical circuit

30. Transformers
Transformers are used to magnetically couple ac voltages from one point in a circuit to another, or to increase or decrease the ac voltage. Companies such as TNB use huge transformers to change voltages for high-voltage transmission lines.
Electronic Instruments
There are four basic electronic instruments normally found in laboratory and will be use throughout the lab session for this course. These instruments include:
DC power supply - provide current and voltage to power electronic circuits.
Function generator – provide electronic signals.
Multimeter – with its voltmeter, ammeter and ohmmeter functions for measuring voltage, current and resistance, respectively
Oscilloscope – observe and measure ac voltages.

31. Voltage
Voltage is the electrical force that moves electrons through a conductor. The pressure also known as EMF (Electro Motive Force) that pushes electrons.

32. Voltage is expressed as;
V = voltage in volts (V)
W = energy in joules (J)
Q = charge in coulombs (C)
One volt is the potential difference (voltage) between two points when one joule of energy is used to move one coulomb of charge from one point to the other.

33. Exercises Determine the voltage
10J / 1C
5J / 2C
100J / 25C
If 50J of energy are available for every 10C of charge, what is the voltage?
500J of energy are used to move 100C of charge through a resistor. What is the voltage across the resistor?

34. Voltage Source
Battery: A battery is a type of voltage source that convert chemical energy into electrical energy. A battery consists of one or more electrochemical cells that are electrically connected.
four basic components: a positive electrode, a negative electrode, electrolyte and a porous separator.
Electrolyte
Porous separator
Negative electrode
Positive electrode - +

35. Solar cells: The operation of solar cells is based on the photovoltaic effect (light energy is converted directly into electrical energy). It has 2 layers of different types of semiconductive materials joined together to form a junction. When one layer is exposed to light, many electrons acquire enough energy to break away from their parent atoms and cross the junction, and thus a voltage is developed.

36. Generator: Electrical generators convert mechanical energy into electrical energy using a principle called electromagnetic induction. A conductor rotated through a magnetic field, and a voltage is produced across the conductor.
Electronic power supply: Electronic power supply does not produce electrical energy from some other from energy. They simply convert the ac voltage from wall outlet to a constant (dc) voltage.
Measuring instrument: A VOLTMETER

37. Current
Current is the movement or flow of charge (electrons) from the negative end of the conductor to the positive end
Current in a conductor material is measured by the number of electrons (amount of charge) that flow past a point in a unit of time
I = current in Ampere (A)
Q = charge of the electrons in coulombs (C)
t = time in seconds (s)

38. One ampere (1A) is the amount of current that exists when a number of electrons having a total charge (1C) move through a given cross-sectional area in one second.
Electricity with electrons flowing in only one direction is called Direct Current (DC). It flows in one direction, positive to negative, steadily. A graph of a DC voltage or current would look like a flat horizontal line.

39. Electricity with electrons flowing back and forth, negative - positive- negative, is called Alternating Current, or AC. It literally changes direction at a certain rate, called its frequency, measured in Hertz.
Ordinary household electricity in Malaysia is 240 VAC, 50 Hz. A graph of 240 VAC is a sine wave. AC can be used at it is in light bulbs and motors, but for electronic devices, it must be stepped down to a lower voltage and then converted to DC. For example, the CPU in many computers typically takes 3.6 volts DC.
Measuring instrument: Ammeter

40. Exercises
10C of charge flow past a given point in a wire in 2s. What is the current in amperes?
If there are 8A of direct current through the filament of a light bulb, how many coulombs have moved through the fillament in 1.5s?

41. Resistance
Resistance, R, is the force that reduces or stops the flow of electrons.
Opposite to current and measured in Ohms ()
The schematic symbol is shown below
Conductance, G, is the reciprocal of resistance.
The unit is in Siemens (S)
Measuring instrument: Ohmmeter

42. Resistor Colour Codes

43. What is the resistance and the tolerance?

44. Alphanumeric Labeling
Two or three digits, and one of the letters R, K, or M are used to identify a resistance value.
The letter is used to indicate the multiplier, and its position is used to indicate decimal point position.

45. Power
When current is forced through a resistance, work is said have been done. Power is the rate of working, represented by "P". Energy is the capacity to do work.
Power is energy per time or the rate of working, represented by "P". The standard unit used in electricity is the Watt (W) = 1 Joule / second.
The amount of power consumed by an electrical device is the rate at which it dissipates energy.

46. Basic Circuit Measurement
Multimeter
Analog Multimeter
Digital Multimeters (DMM)

47. Meter symbols

48. Measuring Current

49. Most analog ammeters have a number of possible settings for the maximum possible current that can be measured; for example: 2 A, 200 mA, 20 mA, 2 mA. You should always start by turning the setting to the highest possible rating (for example, 2 A). If the ammeter reading is too small from the selected scale, then you can reduce the scale to get the reading. It is important not to overshoot the maximum value that can be read.
For example, if the current is about 75 mA, then the ammeter would be set to the 200 mA scale for the most accurate reading. Setting to the 20 mA scale would overload the ammeter and most likely open its internal fuse.

50. Measuring Voltage

51. Measuring Resistance

52. Measured Numbers
Error : The difference between the true value and the measured value
Accuracy : The degree to which a measured value represents the true or accepted value of a quantity. A measurement is said to be accurate if the error is small.
Precision : The repeatability or consistency of a measurement

53. Resolution
The smallest increment of quantity that the meter can measure. The smaller the increment, the better the resolution.
0.01V
0.001V
Chapter 1: Introduction to Electricity

54. Passive Components
Passive components: Components that do not supply voltage or current
Examples
Resistors
Capacitors
Inductor
Transformer

55. Active Components The components that have their own power source.
Passive components are used in conjunction with active components to form an electronic system
Voltage and current sources
Battery, Generator, Fuel cell
Transistor
Integrated Circuit (IC)

56. Electrical Safety
Electrical shock :when voltage is applied across two points on human body , it caused current to flow through the body
The severity of the resulting electrical shock depends on the amount of voltage and the path that the current takes through the body
Effects of current on the human body:
Depends on voltage and body resistance.
Body resistance:
Typically between 10kΩ and 50kΩ
The moisture of the skin and body mass also affects the resistance between two points

57. Chapter 1: Electrical Safety
Some of safety precautions :
Avoid contact with any voltage source. Turn off power before you work on circuits when touching circuit parts is required.
Do not work alone. A telephone should be available for emergencies.
Remove rings, watches, and other metallic jewelry when you work on circuits.
Always wear shoes and keep them dry
Do not stand on metal or wet floor