EET101 LITAR ELEKTRIK 1 ELECTRIC CIRCUIT 1 SEM Lecturer : Wan Nur Suryani Firuz Bt Wan Ariffin Office: KKF 8C Reference Book: 1. Fundamentals of Electric Circuits – Alexander sadiku (3 rd edition) 2. Electric Circuits Fundamentals – FLOYD (7 Th edition) 3. Basic Engineering Circuit Analysis – J.David Irwin & R.Mark Nelms( 9 th edition)

Syllabus - EET 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.

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 reactances, Kirchhoff’s Laws in frequency domain, techniques of circuit analysis in frequency domain Chap 7 : Sinusoidal Steady-State Power Calculation Instantanenous 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 - EET 101

COURSE STRUCTURE Final Exam = 50% Laboratory = 20% Test (2 test) = 20% Test 1 – 6 September 2008 Test 2 – 18 October 2008 Assignment = 10% Group & Tutorial Total : =100%

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

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.

SI UNIT Unit SI 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

Standardized prefixes to signify powers of 10 Power PrefixSymbol TeraT 10 9 GigaG 10 6 MegaM 10 3 Kilok Milim Micro µ Nanon Picop Femtof Attoa

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.

ELECTRIC UNITS Charge»»»Coulomb (C) Current»»»Ampere (A) Voltage»»»Volt (V) Resistance»»»Ohm (  ) Power»»»Watt (W)

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

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

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.

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

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

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 Voltage VOLTAGE

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.

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

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

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.

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.

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

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

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

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.

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

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.

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 : resistore, inductor, capacitor, diode and etc

Independent source Voltage Current

Dependent source VoltageCurrent

Ideal voltage source connected in series

Ideal current source connected in parallel

Symbol of circuit elements Resistor R UNIT: Ohm (Ω)

Resistor colour code

Resistor Colour Codes Yellow 4  10 % Silver 7 Violet 00 Red

Resistor Colour Codes Green = 5Blue = 6Orange = 3 Gold =  5 % 56 x 10 3  5 % =56000  5 % =56 k  5 %

Resistor Colour Codes  2% = 464 k  2%

Conductance Conductance is a measure of the ability of an element to conduct electric current Inverse of resistance Units: Siemens (S) or mhos

Capacitor C UNIT: Farad (F)

Inductor L UNIT: Henry (H)

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.

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

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

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

Example: Find the Nodes + - VsVs node

Example: Find the loops loop

OHM LAW George 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.

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)

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)

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.

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)

The voltage drops around any closed loop must equal the applied voltages

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.

PARALLEL-SERIES CIRCUIT MODEL SERIES PARALLEL

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

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

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

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

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

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.

CIRCUIT WITH DEPENDENT SOURCE

Using KVL on the first loop, Using KCL on the second loop,

Solve the equations,

Using Ohm law for the resistor,