basic engineering circuit, Lecture notes of Electrical Circuit Analysis

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Circuit Analysis: EE

Engr. Dr. Muhammad Waqas Email: [email protected], Room: G- TA: Ms. Areeba Lab Instructor: Engr. Samman Surraya 1

Text Book:

1. Basic Engineering Circuit Analysis, 10th^ edition, J. David Irwin and R. Mark Nelms
2. Introductory to Circuit Analysis, 13th^ edition, Robert. L. Boylested

Reference Book:

Fundamentals Of Electric Circuits by Alexander

Assignments and Plagiarism Policy

• Assignment must be written on an A-4 size paper

or it will NOT be accepted.

• Submit your assignments within due time.

• Any assignment(s) submitted at the end of the

lecture or during lecture will NOT be accepted.

• Assignments must be collected in lecture hall and

will not be accepted in office.

• Those involved in plagiarism will get zero marks

for their assignment(s).

Course Objective and Learning Outcomes

• (^) Be able to differentiate among different circuit parameters/elements e.g; resistor, capacitor inductor, impedance, admittance etc and explain their current voltage relationship. (PLO-1)
• (^) Be able to use basic circuit analysis techniques and circuit theorems for calculating various parameters in a DC or AC circuit. (PLO-2)
• (^) Be able to solve RL, RC and RLC circuits using first order and second order differential equations and illustrate the transient response of these circuits graphically. (PLO-2)

Specific Topics

• Circuit elements, sources, vaiables and laws (Kirchoff and Ohm’s law)
• DC circuit analysis by node and mesh methods
• Theorems:
  • Superposition
  • Thevenin Equivalent
  • Norton Equivalent
  • Maximum Power Transfer
• Inductors & Capacitors
• Operational amplifier circuits
• Transient analysis
  • First order circuits
  • Second order circuits
• AC Circuits
  • Sinusoids and complex forcing functions
  • Phasors and Phasor analysis in AC Circuits

Chapter 1: Basic Electric Circuit

Concepts

8

Current

• (^) Rate of flow of charge per unit time is called current
  • (^) Denoted by I
  • (^) Current (I) = Charge (Q) /Time (t)
    • (^) I = coulombs/sec = Ampere → SI Unit
  • (^) Flow of charge from one point to another through a conductor is actually flow of electron
• (^) There are two types of currents
  • (^) DC (Direct Current)
    • (^) The polarity of the current does not change
      • (^) e.g, car batteries, electronic gadgets, cell phones
  • (^) AC (Alternating Current)
    • (^) The polarity of the current changes every half cycle
      • (^) Common current found in every house hold to run refrigerator, washing machine, stoves etc. AC DC

Circuit Elements: Absorbers and Suppliers Of Energy

• (^) One of the elements in the figure is supplying energy while the other is absorbing the energy? - (^) (Hint: Current’s exit & positive terminal)
• (^) Charges entering the bulb have higher energy than charges leaving the bulb 11

Contd..

Conventional Current and Actual Current

• (^) Conventional current always flows from positive terminal to negative terminal - (^) Flow of positive charge
• (^) In reality actual current or the electron current flows from negative terminal to positive terminal - (^) Flow of negative charge or electron
• (^) In this course we will treat all currents and their direction of flow to be conventional i.e; current due to positive charge, hence; - (^) Positive will always be higher potential - (^) Negative will always be lower potential

• (^) The variable for the voltage v(t) is defined as the voltage across the element with the positive reference at the same terminal that the current variable i(t) is entering.
• (^) This convention is called the passive sign convention and will be so noted in the remainder of this book.
• (^) The product of v and i, with their attendant signs, will determine the magnitude and sign of the power.
• (^) If the sign of the power is positive, power is being absorbed by the element;
• (^) if the sign is negative, power is being supplied by the element.

Basic Quantities

Basic Quantities: Power

• (^) Which one is absorbing power and which one is supplying power?
• (^) Current direction in figure (b)?
• (^) Power =? 17 -2V x 4A = -8W 2V x (-2A) = -4W

Electrical Circuits and Conservation Of Energy

• (^) Energy → Joules
• (^) Power → Watt →Joules/sec
  • (^) Thus a relation between power and energy exists Þ (^) Power can also be conserved in an electrical network (Tellegen’s Theorem)
• (^) Power = Voltage x Current = VI Tellegen’s Theorem: The algebraic sum of all the Powers absorbed/supplied by all elements in an electrical network is zero OR Power Supplied in a network is equal to the power absorbed 19

Indpendant Sources Independent Voltage Source:

• (^) A two terminal element that maintains a specified voltage between its terminals regardless of the current through it
• (^) Symbolically represented by a circle Independent Current Source:
• (^) Two terminal element that maintains a specified current regardless of the voltage across its terminals
• (^) Symbolically represented by a circle with an arrow
• (^) Arrow indicates positive direction of current flow 20