1. CHAPTER 1 - Introduction to electric circuit
BASIC ELECTRICAL CONCEPTS AND RESISTIVE CIRCUITS
- Introduction to electric circuit
- SI Unit, Electrical Unit
- Electric Charge, Current, Voltage, Resistance and Power
- Basic circuit elements : Active element and Passive element

2. Continue…
- Ohm’s Law
- Kirchhoff Current Law (KCL) and Kirchhoff Voltage Law (KVL)
- Series and Parallel circuit
- Voltage Divider Rule (VDR) and Current Divider Rule (CDR)

3. - Introduction to electric circuit - SI Unit, Electrical Unit
BASIC ELECTRICAL CONCEPTS AND RESISTIVE CIRCUITS
- Introduction to electric circuit
- SI Unit, Electrical Unit
- Electric Charge, Current, Voltage, Resistance and Power
- Basic circuit elements : Active element and Passive element

4. Introduction to Electric Circuit
Electric circuit can be defined as an interconnection between components or electrical devices for the purpose of communicating or transferring energy from one point to another. The components of electric circuit are always referred to as circuit elements.

5. - Introduction to electric circuit - SI Unit, Electrical Unit
BASIC ELECTRICAL CONCEPTS AND RESISTIVE CIRCUITS
- Introduction to electric circuit
- SI Unit, Electrical Unit
- Electric Charge, Current, Voltage, Resistance and Power
- Basic circuit elements : Active element and Passive element

6. QUANTITY AND ELECTRICAL UNIT
SI Unit
SI : International System of Unit that had been introduced by National Bureau of Standards in 1964
Quantity
Basic Units
Symbol
Length
Meter m
Mass
Kilogram kg
Time
Second s
Electric Current
Ampere A
Temperature
Kelvin K
Luminous
intensity
candela cd

7. SI unit consists of decimal system that connected to the smaller or bigger of basic unit and by using prefix for the power of tenth:
Multiplier
Prefix
Symbol
1018
Exa E
1015
Peta P
1012
Tera T
109
Giga G
106
Mega M
103
Kilo k
102
Hector h
101
Deka da
10-1
Deci d
10-2
Centi
10-3
Mili m
10-6
Micro 
10-9
Nano n
10-12
Pico p
10-15
Femto f
10-18
Atto a

8. The derived unit commonly used in electric circuit theory

9. - Introduction to electric circuit - SI Unit, Electrical Unit
BASIC ELECTRICAL CONCEPTS AND RESISTIVE CIRCUITS
- Introduction to electric circuit
- SI Unit, Electrical Unit
- Electric Charge, Current, Voltage, Resistance and Power
- Basic circuit elements : Active element and Passive element

10. ELECTRIC CHARGE Polarity: type of charge (-ve or +ve)
Electron: -ve charge
Proton: +ve charge
Electric charge create electric field of force
Electric charge is an electrical property of the atomic particles of which matter consists measured in coulombs (C).

11. Continued…
The charge e on one electron is negative and equal in magnitude to  C which is called as electronic charge. The charges that occur in nature are integral multiples of the electronic charge.

12. ELECTRIC CHARGE Quantity is Charge (Q) Base Unit is Coulomb (C)
Examples of correct usage:
Charge = 10 Coulombs
Q = 10 C

13. Current is defined as the movement of charge in a specified direction.

14. Electric Current Terminology
Quantity is Current (I)
Base Unit is Ampere (A)
An Ampere = Coulomb per second
Examples of usage:
Current = 10 Amperes
I = 10 A

15. Electric Current Relationships
Charge Q
Current =
I = t
Time
Electric current i = dq/dt. The unit of ampere can be derived as 1 A = 1C/s.
Examples: Q
10 C
= 2 A
I = = t
5 s

16. Direct current (arus terus)
TYPES OF CURRENT
Alternating current
(arus ulangalik)
Direct current (arus terus)
A direct current (dc) is a current that remains constant with time.
An alternating current (ac) is a current that varies sinusoidally with time. (reverse direction)

17. A conductor has a constant current of 5 A.
Example
A conductor has a constant current of 5 A.
How many electrons pass a fixed point on the conductor in one minute?

18. Total no. of charges pass in 1 min is given by
Solution
Total no. of charges pass in 1 min is given by
5 A = (5 C/s)(60 s/min) = 300 C/min
Total no. of electronics pass in 1 min is given

19. VOLTAGE It is a potential energy difference between two points.
Voltage is the electric pressure or force that causes current.
It is a potential energy difference between two points.
It is also known as an electromotive force (emf).

20. Voltage Terminology Examples of usage: Voltage = 20 Volts V = 20 V
Quantity is Voltage (V)
Base Unit is Volt (V)
A Volt = Joule per second
Examples of usage:
Voltage = 20 Volts
V = 20 V

21. Voltage Relationships
Energy W
Voltage =
V =
Charge Q
Examples: W
24 J
= 6 V
V = = Q
4 C

22. Resistance is the opposition a material offers to current.
Resistance is determined by:
Type of material (resistivity)
Temperature of material
Cross-sectional area
Length of material

23. Resistance Terminology
RESISTANCE (R)
Quantity is
Base Unit is
OHM (W)
An ohm = Volt per ampere
Example of usage:
Resistance = 14 ohm
R = 14 Ω

24. Resistance Relationships
Resistivity x length KL
Resistance =
R = A
area
Example: KL
1.4 x10-6 W· cm x 5 x104 cm
R = = A
2 cm2
= 5 W

25. Power is the rate of using energy or doing work.
Work (W)
Energy (W)
consists of a force moving through a distance.
is the capacity to do work.
Joule (J)
is the base unit for both energy and work.

26. Power Terminology Example of usage: Quantity is POWER (P) Base Unit is
WATT (W)
A watt = Joule per second
Example of usage:
Power = 200 Watts
P = 200 W

27. Power Relationships Energy W Power = P = t Time Example: W 200 J

28. - Introduction to electric circuit - SI Unit, Electrical Unit
BASIC ELECTRICAL CONCEPTS AND RESISTIVE CIRCUITS
- Introduction to electric circuit
- SI Unit, Electrical Unit
- Electric Charge, Current, Voltage, Resistance and Power
- Basic circuit elements : Active element and Passive element

29. ACTVIVE ELEMENT AND PASSIVE ELEMENT
Active Element– elements capable of generating electrical energy. For example:
Voltage source
Current source
Passive Element – elements are not capable of generating electrical energy. For example:
Resistor (dissipates energy)
Capacitor and Inductor (can store or release energy)

30. Independent source Current Voltage
This source maintains a specified voltage between its terminals but has no control on the current passing through it. The symbol of the independent voltage source is a plus-minus sign enclosed by a circle.
Current
This source maintains a specified current through its terminals but has no control on the voltage across its terminals. The symbol of the independent current source is an arrow enclosed by a circle.
Voltage

31. Dependent source Voltage Current
This kind of voltage source has a specified voltage between its terminals but it is dependable on some other variable defined somewhere in the circuit. The symbol for the dependent voltage source is a plus-minus sign enclosed by a diamond shape. The value of the dependent current source is ρix (ohms) where ρ is the scale factor or gain.
This kind of current source has a specified current between its terminals but it is dependent on some other variable defined somewhere in the circuit. The symbol for the dependent current source is an arrow enclosed by a diamond shape. The value of the dependent current source is αVx (in Siemens) where α is the scale factor or gain.

32. Example Obtain the voltage v in the branch shown in Figure below for i2 = 1A.

33. Therefore, v = 10 + vx = 10 + 15(1) = 25 V
Solution
Voltage v is the sum of the current-independent 10-V source and the current-dependent voltage source vx.
Note that the factor 15 multiplying the control current carries the units Ω.
Therefore, v = 10 + vx = (1) = 25 V

34. Circuit symbol of resistor
Resistor is passive element that dissipates electrical energy. Linear resistor is the resistor that obeys Ohm’s law. R
UNIT: Ohm (Ω)

35. Resistor colour code

36. Resistor Colour Codes
Yellow 4 7
Violet 00
Red
±10 %
Silver

37. C CAPACITOR UNIT: Farad (F)
Electrical component that consists of two conductors separated by an insulator or dielectric material.
Its behavior based on phenomenon associated with electric fields, which the source is voltage.
A time-varying electric fields produce a current flow in the space occupied by the fields.
Capacitance is the circuit parameter which relates the displacement current to the voltage.

38. A capacitor with an applied voltage
Plates – aluminum foil
Dielectric – air/ceramic/paper/mica
Plates – aluminum foil
Dielectric – air/ceramic/paper/mica

39. Circuit symbols for capacitors
(a) Fixed capacitor
(b) Variable capacitor

40. The amount of charge stored, q = CV.
Circuit parameters
The amount of charge stored, q = CV.
C is capacitance in Farad, ratio of the charge on one plate to the voltage difference between the plates. But it does not depend on q or V but capacitor’s physical dimensions i.e.,
 = permeability of dielectric in Wb/Am
A = surface area of plates in m2
d = distance between the plates m

41. L INDUCTOR UNIT: Henry (H)
Electrical component that opposes any change in electrical current.
Composed of a coil or wire wound around a non-magnetic core/magnetic core.
Its behavior based on phenomenon associated with magnetic fields, which the source is current.
A time-varying magnetic fields induce voltage in any conductor linked by the fields.
Inductance is the circuit parameter which relates the induced voltage to the current.

42. Typical form of an inductor

43. Circuit symbols for inductors
Variable
iron-core
Air-core
iron-core

44. - Ohm’s Law
- Kirchhoff Current Law (KCL) and Kirchhoff Voltage Law (KVL)
- Series and Parallel circuit
- Voltage Divider Rule (VDR) and Current Divider Rule (CDR)

45. OHM’S LAW
Georg Simon Ohm ( ) formulated the relationships among voltage, current, and resistance as follows:
The current in a circuit is directly proportional to the applied voltage and inversely proportional to the resistance of the circuit.

46. Calculating Current V R = 24 V 1200 W I = = 0.02 A = 20 mA Vs = 24 V R
1.2 kW
Vs =
24 V V R =
24 V
1200 W
I =
= A
= 20 mA

47. Calculating Resistance
Vs =
12 V A
0.02 A V I =
12 V
0.02 A
R =
= 600 W
= 0.6 k W

48. Calculating Voltage A V = IR = 0.025 A x 470 W = 11.75 V 0.025 A
Vs = ? A
0.025 A
V =
IR =
0.025 A x 470 W =
11.75 V

49. Calculating Power A V IV = P = 0.25 A x 67.5 V = 16.9 W P = I2R =
0.25 A x A x 270 W =
16.9 W
P = V2/R =
(67.5 V x V) / 270 W =
16.9 W

50. A branch represents a single element such as a voltage source or a resistor.
A node is the point of connection between two or more branches.
A loop is any closed path in a circuit.
A network with b branches, n nodes, and l independent loops will satisfy the fundamental theorem of network topology:

51. How many branches, nodes and loops are there?
Example:
Original circuit
Equivalent circuit
How many branches, nodes and loops are there?

52. - Ohm’s Law
- Kirchhoff Current Law (KCL) and Kirchhoff Voltage Law (KVL)
- Series and Parallel circuit
- Voltage Divider Rule (VDR) and Current Divider Rule (CDR)

53. KIRCHHOFF’S LAW Gustav Robert Kirchhoff (1824 – 1887)
Models relationship between:
circuit element currents (KCL)
circuit element voltages (KVL)
He introduces two laws:
Kirchhoff Current Law (KCL)
Kirchhoff Voltage Law (KVL)

54. Kirchhoff’s Current Law (KCL)
Current entering node = current exiting
Convention: +i is exiting, -i is entering
For any circuit node:

55. Kirchhoff’s Current Law (KCL)
Kirchhoff’s Current Law (KCL) states that the algebraic sum of current entering a node must be equal to that of leaving the same node.

56. Determine the current I for the circuit shown in the figure below.
Example
Determine the current I for the circuit shown in the figure below.
I + 4-(-3)-2 = 0
I = -5A
This indicates that the actual current for I is flowing in the opposite direction.
We can consider the whole enclosed area as one “node”.

57. Kirchhoff’s Voltage Law (KVL)
voltage increases = voltage decreases
Convention: hit minus (-) side first, write negative
For any circuit loop:

58. Kirchhoff’s Voltage Law (KVL)
Kirchhoff’s Voltage Law states that the algebraic sum of voltage drop in a loop must be equal to that of voltage rise in the same loop. Stated it in a different way is that the algebraic sum of all voltages around a loop must be zero.

59. Applying the KVL equation for the circuit of the figure below.
Example
Applying the KVL equation for the circuit of the figure below.
va-v1-vb-v2-v3 = 0
V1 = IR1 v2 = IR2 v3 = IR3
va-vb = I(R1 + R2 + R3)

60. - Ohm’s Law
- Kirchhoff Current Law (KCL) and Kirchhoff Voltage Law (KVL)
- Series and Parallel circuit
- Voltage Divider Rule (VDR) and Current Divider Rule (CDR)

61. SERIES AND PARALLEL CIRCUIT
Resistor below is arranged in series connection:
The equivalent resistance for any number of resistors in series connection is the sum of each individual resistor.
Req = R1 + R2 + ……….+ RN

62. CURRENT IN SERIES CIRCUIT VOLTAGE IN SERIES CIRCUIT
Current in series circuit is the same as in each circuit element.
VOLTAGE IN SERIES CIRCUIT
Voltage (VT) in series circuit is the total voltage of each element circuit.

63. Resistor below is arranged in parallel connection:
The equivalent resistance for any number of resistors in parallel connection is obtained by taking the reciprocal of the sum of the reciprocal of each single resistor in the circuit.

64. Equivalent resistance:

65. For the circuit which have two resistors in parallel connection:

66. CURRENT IN PARALLEL CIRCUIT VOLTAGE IN PARALLEL CIRCUIT
Current in series circuit is equal to the total current for each element circuit
VOLTAGE IN PARALLEL CIRCUIT
Voltage (VT) in series circuit is the same as for each element circuit

67. - Ohm’s Law
- Kirchhoff Current Law (KCL) and Kirchhoff Voltage Law (KVL)
- Series and Parallel circuit
- Voltage Divider Rule (VDR) and Current Divider Rule (CDR)

68. VOLTAGE DIVIDER
Whenever voltage has to be divided among resistors in series use voltage divider rule principle.

69. By applying Ohm’s Law:
Voltage at resistor R2:

70. CURRENT DIVIDER
Whenever current has to be divided among resistors in parallel, use current divider rule principle.

71. By applying Ohm’s Law:

72. So, to find current, I1 and I2 :