This document discusses the applications of Thevenin's and Norton's theorems. Thevenin's theorem states that any linear electrical network can be reduced to an equivalent circuit with a voltage source in series with a resistor. This is useful when a load resistor in a complex circuit needs to be changed. Norton's theorem states that any linear network can be represented by a current source in parallel with a resistor. Both theorems allow simplifying complex circuits for analysis. Thevenin's theorem is applied to power systems and circuits where the load resistance varies. Norton's theorem allows focusing on part of a circuit by reducing the rest to a simple equivalent.

1. GANDHINAGAR INSTITUTE
OF TECHNOLOGY
Case study on:
Application of Thevenin and Norton’s
theorem
Guided by: pratik
Branch: I.T.(C)
Academic Year:2013-14

2.  Application of Thevenin’s Theorem:
 Thevenin’s theorem is a simplification technique used in circuit analysis. Any complex
network with several voltage sources & resistors can be reduced to a Thevenin’s equivalent
circuit consist of a single voltage source and a series resistance connected to a load.
 Thevenin’s theorem can be applied in various networks and these applications of Thevenin
theorem are,
 This theorem is very useful tool in circuit analysis method where the network is linear &
bilateral.
 Practically, Thevenin’s Theorem is considered as a very useful tool in analyzing a special
type of circuits where a particular load resistor in the circuit is varying, the voltage across it
and current through it is easily calculated by analyzing the circuit with each trial value of that
load resistance.
 Measurement of resistance with the Wheatstone bridge is a important application of the
Thevenin’s theorem.
 However, Thevenin’s equivalent circuits of active networks consisting of transistors, voltage
Sources such as batteries etc are very useful in circuit design.
 Another practical application of this theorem is, the Thevenin theorem is used to solve
asymmetrical series faults in any network.
 By using Thevenin's theorem we can make a complex circuit into a simple circuit with a
voltage source(Vth) in series with a resistance(Rth)
 Thevenin's Theorem is especially useful in analyzing power systems and other circuits where
one particular resistor in the circuit (called the "load" resistor) is subject to change, and re-calculation
of the circuit is necessary with each trial value of load resistance, to determine
voltage across it and current through it.
 Thevenin's theorem is only valid for linear and bilateral networks. Practically, linearity of
any circuit is over a certain range. Hence it is only valid for certain range.
 Thevenin's Theorem is especially useful in analyzing power systems and other circuits where
one particular resistor in the circuit (called the “load” resistor) is subject to change, and re-

3. calculation of the circuit is necessary with each trial value of load resistance, to determine
voltage across it and current through it.
 Application of Norton’s Theorem:
 Norton’s Theorem allows us to replace a complicated circuit with a simple equivalent
circuit containing only a current source and a parallel connected resistor. This
theorem is very important from both theoretical and practical viewpoints.
 It is important to note that the Norton equivalent circuit provides equivalence at the
terminals only. Obviously, the internal structure and therefore the characteristics of
the original circuit and its Norton equivalent are quite different.
Concisely stated, Norton’s Theorem says:
 “Any two-terminal linear circuit can be replaced by an equivalent circuit consisting of
a current source (IN) and a parallel resistor (RN).”
 We want to concentrate on a specific portion of a circuit. The rest of the circuit can be
replaced by a simple Norton equivalent.
 We have to study the circuit with different load values at the terminals. Using the
Norton equivalent, we can avoid having to analyze the complex original circuit each
time.
 In some ways Norton’s Theorem can be thought of as the opposite to “Thevenins
Theorem”, in that Thevenin reduces his circuit down to a single resistance in series
with a single voltage. Norton on the other hand reduces his circuit down to a single
resistance in parallel with a constant current source.
 Norton’s Theorem states that “Any linear circuit containing several energy sources
and resistances can be replaced by a single Constant Current generator in parallel
with a Single Resistor“.
 Norton's Theorem states that it is possible to simplify any linear circuit, no matter
how complex, to an equivalent circuit with just a single current source and parallel
resistance connected to a load. Just as with Thevenin's Theorem, the qualification of

4. “linear” is identical to that found in the Superposition Theorem: all underlying
equations must be linear (no exponents or roots).
 The application of Norton’s theorem is similar to the application of Thevenin’s
theorem. It can be illustrated with the help of a sketch.
 Thevenin’s resistance is obtained as described above. These steps have been
described earlier, for getting Thevenin’s resistance for Thevenin’s theorem.