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Electric Circuits: Methods of Analysis

1. The document discusses various circuit analysis methods including superposition, source transformation, Thevenin's theorem, and Norton's theorem. 2. Under superposition, the circuit is analyzed by considering one independent source at a time. For Thevenin's theorem, any linear two-terminal circuit can be replaced by a voltage source and resistor combination. 3. Norton's theorem similarly replaces a circuit with a current source and resistor, and maximum power transfer occurs when the load resistance equals the Thevenin resistance as seen from the load. The document provides examples and homework problems for each topic.

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JalalAlRoumy
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47 views25 pages

Electric Circuits: Methods of Analysis

1. The document discusses various circuit analysis methods including superposition, source transformation, Thevenin's theorem, and Norton's theorem. 2. Under superposition, the circuit is analyzed by considering one independent source at a time. For Thevenin's theorem, any linear two-terminal circuit can be replaced by a voltage source and resistor combination. 3. Norton's theorem similarly replaces a circuit with a current source and resistor, and maximum power transfer occurs when the load resistance equals the Thevenin resistance as seen from the load. The document provides examples and homework problems for each topic.

Uploaded by

JalalAlRoumy
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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1

Electric Circuits

Chapter 4
Methods of Analysis
Dr Jalal Al Roumy

Israa University
2019/2020
Superposition:
2

 It states that the voltage across (or current through) an


element in a linear circuit is the algebraic sum of the
voltages across (or currents through) that element due to
each independent source acting alone.
Superposition:
3

 We consider one independent source at a time while all


other independent sources are turned off. Dependent
sources are left intact because they are controlled by
circuit variables.

 Thus, we replace every voltage source by a short circuit,


and every current source, by an open circuit.
Example 4.3:
4
Exercise 4.3:
5
Exercise 4.4:
6
Source Transformation:
7

 Source transformation is the process of replacing a


voltage source Vs in series with a resistor R by a current
source Is in parallel with a resistor R, or vice versa.
Example 4.6:
8
Exercise 4.6:
9
Thevenin’s Theorem:
10

 The theorem states that a linear two-terminal circuit can


be replaced by an equivalent circuit consisting of a
voltage source VTh in series with a resistor RTh.
Case 1: Without Dependent Sources
11

 VTh is the open-circuit voltage at the terminals and RTh is


the equivalent resistance at the terminals when all of the
independent sources are turned off.
Case 2: With Dependent Sources
12

 We turn off all independent sources and keep the dependent


sources on. Then, we apply a voltage source vo at terminals
a & b and determine the resulting current io.

 Alternatively, we may insert a current source io at terminals a


& b and find the terminal voltage vo.
Thevenin’s Theorem:
13

 Thevenin’s theorem is very important in circuit analysis


as large circuit may be replaced by a single independent
voltage source and a single resistor. The equivalent
network behaves the same way as the original circuit.
Example 4.8:
14
Example 4.9:
15
Example 4.10:
16
Norton’s Theorem:
17

 IN is the short-circuit current through the terminals and


RN is the equivalent resistance at the terminals when the
independent sources are turned off.
Norton’s Theorem:
18

 Dependent and independent sources are treated the


same way as in Thevenin’s theorem.
Example 4.11:
19
Exercise 4.11:
20
Exercise 4.12:
21
Maximum Power Transfer:
22

 Maximum power is transferred to the load when the load


resistance equals the Thevenin resistance as seen from
the load (RL = RTh).
Maximum Power Transfer:
23

 The source and load are said to be matched when RL = RTh.


Example 4.13:
24
HW #4:
25

 4.1, 4.11, 4.20, 4.22, 4.36, 4.39, 4.41, 4.47, 4.66 & 4.71.

 Assignment is due to 2/11/2019.

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