1. 1 CHAPTER 1 EKT 101 [Electric Circuit I]: V2010/11 School of Computer and Communication Engineering, UniMAP Prepared By: Prepared By: Shahadah binti Ahmad Shahadah binti Ahmad Variables & Circuit Elements

2. 2 Lecturer : Shahadah Ahmad shahadah@unimap.edu.my Office: KKF 8B Textbook: (1) Fundamentals of Electric Circuits – Alexander sadiku (4 th edition) Reference book: (2) Electric Circuits Fundamentals – FLOYD (7 Th edition) (3) Basic Engineering Circuit Analysis – J.David Irwin & R.Mark Nelms( 9 th edition)

3. 3 Syllabus - EKT 101 Chap 1 : Circuit Elements and Variables Overview of circuit analysis, SI unit, voltage and currents, power, energy, elements on the circuit (passive and active) voltage and current source, Ohm’s Law, Kirchhoff’s Law, circuit model, circuit with dependent source. Chap 2 : Resistive Circuit Series / Parallel circuit, voltage divider circuit, current divider circuit, voltage and current measurement, Wheatstone Bridge, equivalent circuit for delta-wye (Pi-Tee). Chap 3 : Circuit Analysis Methods Introduction to the Node-Voltage Method, the Node-Voltage Method with dependent sources and special cases, introduction to Mesh-Current Method, Mesh-Current Method with dependent sources and special cases, source transformations, Thevenin and Norton equivalent circuit, maximum power transfer and superposition. Chap 4 : Inductance and Capacitance Inductor, relationship between voltage, current, power and energy, capacitor, relationship between voltage, current, power and energy, series- parallel combinations for inductance and capacitance.

4. 4 Chap 5 : First-Order and Second-Order Response of RL and RC Circuit Natural response of RL and RC Circuit, Step Response of RL and RC Circuit, general solutions for natural and step response, sequential switching, introduction to the natural and step response of RLC circuit, natural response of series and parallel RLC circuit, Step response of series and parallel RLC circuit. Chap 6: Sinusoidal Steady-State Analysis The sinusoidal source, the sinusoidal response, the phasor and phasor diagram, the passive circuit elements in the frequency domain, impedances and reactance, Kirchhoff’s Laws in frequency domain, techniques of circuit analysis in frequency domain Chap 7 : Sinusoidal Steady-State Power Calculation Instantaneous power, average (active) and reactive power, the rms value power calculation, complex and power triangle, the maximum power transfer Chap 8 : Three Phase System Circuit Single and Three Phase System (Y and Δ circuit), balanced three phase voltage sources, Y – Y circuit analysis, Y - Δ circuit analysis, power calculation in three phase balanced circuit, average power measurement in three phase circuit. Syllabus - EKT 101

5. 5 Basic Electric Circuit Concepts  Review SI  Know the definition of basic electrical quantities : voltage, current, and power  Know the symbols for and definition of independent and dependent sources  Be able to calculate the power absorbed by a circuit element using the passive sign convention

6. 6 Circuit Elements & Variables  Overview of circuit analysis  SI unit  Voltage, currents, power, energy,  elements on the circuit (passive and active) voltage and current source  Ohm’s Law and Kirchhoff’s Law  circuit model  circuit with dependent source.

7. 7 SI Unit SI: International System of Unit is used by all the major engineering societies and most engineers throughout the world. QuantityBase unitSymbol LengthMeterm MassKilogramkg Timeseconds Electric currentAmpereA Thermodynamic temperature KelvinK Luminous intensity candelacd

8. 8  Standardized prefixes to signify powers of 10 Power PrefixSymbol 10 12 TeraT 10 9 GigaG 10 6 MegaM 10 3 Kilok 10 0 10 -3 Milim 10 -6 Micro µ 10 -9 Nanon 10 -12 Picop 10 -15 Femtof 10 -18 Attoa

9. 9  Overview of circuit analysis  SI unit  Voltage, currents, power, energy,  elements on the circuit (passive and active) voltage and current source  Ohm’s Law and Kirchhoff’s Law  circuit model  circuit with dependent source. Circuit Elements & Variables

10. 10 Electric Units  Charge»»»Coulomb (C)  Current»»»Ampere (A)  Voltage»»»Volt (V)  Resistance»»»Ohm ()  Power»»»Watt (W)

11. 11 Electric charge is a property possessed by both electrons and protons. Quantity is CHARGE (Q) COULOMB (C) Base Unit is Examples of correct usage: Charge = 15 Coulombs Q = 15 C

12. 12 Current is the movement of charge in a specified direction. Current

13. 13 Electric Current Terminology Quantity is CURRENT (I) AMPERE (A) Base Unit is Examples of correct usage: Current = 12 Amperes I = 12 A An ampere equals a coulomb per second.

14. 14 Electric Current Relationships Current = I = Examples: Charge Time Q t I = Q t = 14 C 10 s = 1.4 A t = Q I = 14 C 1.4 A = 10 s

15. 15 Types of Current: Direct current (arus terus) Alternating current (arus ulangalik) Damped alternating current (arus ulangalik teredam) Exponential current AC DC ex: Used to run refrigerator, stove, washing machine, and so on… ex batteries – used in automobiles or flashlight

16. 16  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) or potential. Definition of VoltageVoltage

17. 17 Voltage Terminology Quantity is VOLTAGE (V) VOLT (V) Base Unit is Examples of correct usage: Voltage = 32 Volts V = 32 V A volt equals a joule per coulomb.

18. 18 Voltage Relationships Voltage = V = Examples: Energy Charge W Q V = W Q = 56 J 2 C = 28 V Q = W V = 84 J 21 V = 4 C

19. 19 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 Definition of Resistance Resistance

20. 20 Some Factors That Determine Resistance For a specific material and temperature, this block has given amount of resistance. Doubling the length of the block, Doubling the cross-sectional area, doubles the resistance. halves the resistance.

21. 21 Resistance Terminology Quantity is RESISTANCE (R) OHM (  ) Base Unit is Examples of correct usage: Resistance = 47 ohms R = 47  An ohm equals a volt per ampere.

22. 22 Resistance Relationships Resistance = R = Example: Resistivity x length area KL A R = KL A = = 0.1  1.4 x10 -6   cm x 2 x10 4 cm 0.28 cm 2

23. 23 Work (W) consists of a force moving through a distance. Energy (W) is the capacity to do work. The joule (J) is the base unit for both energy and work. The amount of work done equals the amount of energy used (converted). Fifty joules of energy are required to do fifty joules of work. ENERGY

24. 24 Power is the rate of using energy or doing work. “Using energy” means that energy is being converted to a different form. Definition of Power POWER

25. 25 Power Terminology Quantity is POWER (P) WATT (W) Base Unit is Examples of correct usage: Power = 120 Watts P = 120 W A watt equals a joule per second.

26. 26 Power Relationships Power = P = Examples: Energy Time W t P = W t = 158 J 20 s = 7.9 W W = Pt = 75 W x 25 s = 1875 J

27. 27 Circuit Elements & Variables  Overview of circuit analysis  SI unit  voltage and currents, power, energy,  elements on the circuit (passive and active) voltage and current source  Ohm’s Law and Kirchhoff’s Law  circuit model  circuit with dependent source.

28. 28 Active and Passive Elements Circuit Elements Active elements capable of generating electric energy Example : voltage and current sources Passive elements incapable of generating electric energy Example : resistor, inductor, capacitor, diode and etc

29. 29 Independent Source Voltage Current

30. 30 VoltageCurrent Dependent Source

31. 31 Ideal Voltage Source Connected in Series

32. 32 Ideal Current Source Connected in Parallel

33. 33 Symbol of Circuit Elements  Resistor R UNIT: Ohm (Ω)

34. 34 Resistor Color Code

35. 35 Yellow 4  10 % Silver 7 Violet 00 Red Resistor Color Code

36. 36 Green = 5white= 9Orange = 3 Gold =  5 % 59 x 10 3  5 % =59,000  5 % =59 K  5 % Resistor Color Code

37. 37 40 0 064  2% = 464 k  2% Resistor Color Code

38. 38 Conductance  Conductance is a measure of the ability of an element to conduct electric current  Inverse of resistance  The units is Siemens (S) or mhos

39. 39  Capacitor  Inductor C UNIT: Farad (F) L UNIT: Henry (H)

40. 40 Circuit Elements & Variables  Overview of circuit analysis  SI unit  voltage and currents, power, energy,  elements on the circuit (passive and active) voltage and current source  Ohm’s Law and Kirchhoff’s Law  circuit model  circuit with dependent source.

41. 41 Short Circuit  R = 0  no voltage difference exists  all points on the wire are at the same potential.  Current can flow, as determined by the circuit

42. 42 Open circuit  R =   no current flows  Voltage difference can exist, as determined by the circuit

43. 43 Circuit Nodes and Loops  A node is a point where two or more circuit elements are connected.  A loop is formed by tracing a closed path in a circuit through selected basic circuit elements without passing through any intermediate node more than once

44. 44 Example: Find the Nodes + - VsVs node

45. 45 Example: Find the loops loop

46. 46 Ohm’s Law  George Simon Ohm (1787-1854) 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.

47. 47 Kirchhoff Law  Gustav Robert Kirchhoff (1824–1887)  Models relationship between:  circuit element currents (KCL)  circuit element voltages (KVL)  Introduce two laws:  Kirchhoff Current Law (KCL)  Kirchhoff Voltage Law (KVL)

48. 48  Current entering node = current exiting (What goes in, must come out)  Convention: +i is exiting, -i is entering  For any circuit node: Kirchhoff’s Current Law (KCL)

49. 49  No matter how many paths into and out of a single point all the current leaving that point must equal the current arriving at that point. Kirchhoff’s Current Law (KCL)

50. 50  voltage increases = voltage decreases (What goes up, must come down)  Convention: hit minus (-) side first, write negative  For any circuit loop: Kirchhoff’s Voltage Law (KVL)

51. 51  The voltage drops around any closed loop must equal the applied voltages Kirchhoff’s Voltage Law (KVL)

52. 52 Circuit Elements & Variables  Overview of circuit analysis  SI unit  voltage and currents, power, energy,  elements on the circuit (passive and active) voltage and current source  Ohm’s Law and Kirchhoff’s Law  circuit model  circuit with dependent source.

53. 53 PARALLEL-SERIES Circuit Model SERIES PARALLEL

54. 54 This complete circuit uses the following: An energy or power source A control device A load Conductors Insulation (not shown)

55. 55 Calculating Current I =I = VRVR = 36 V 1800  = 0.02 A = 20 mA S 1 SPST R 1.8 k  B 1 36 V

56. 56 Calculating Resistance R = V I V I = 24 V 0.03 A = 800  = 0.8 k  R B 1 24 V A 0.03 A

57. 57 Calculating Voltage V =V = IR =IR = 0.15 A * 270   = 40.5 V R  B1B1 A 0.15 A

58. 58 Calculating Power P =  0.2 A IV =IV = 0.2 A * 54 V  = 10.8 W V 54 V P = I 2 R = 0.2 A * 0.2 A * 270  =10.8 W P = V 2 /R = (54 V * 54 V) / 270  = 10.8 W A

59. 59 Circuit Elements & Variables  Overview of circuit analysis  SI unit  voltage and currents, power, energy,  elements on the circuit (passive and active) voltage and current source  Ohm’s Law and Kirchhoff’s Law  circuit model  circuit with dependent source.

60. 60 Circuit With Dependent Source

61. 61  Using KVL on the first loop,  Using KCL on the second loop,  Solve the equations,

62. 62  Using Ohm law for the resistor,