Page 35 - NETWORK ANALYSIS

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Thevenin Theorem

Thevenin’s theorem states that any linear circuit can be simplified to an

equivalent circuit consisting of a single voltage source with a series resistance
connected to a load. Any complex circuit can be reduced to a Thevenin equivalent

circuit and become easier to determine the value of current for certain load.

iL

Figure 2(a): Thevenin equivalent circuit

There are a few steps to solve the circuit using Thevenin’s theorem.

1) Find the Thevenin resistance, Rth by removing the load resistor and all the power
sources in the circuit. Remove all sources by replacing voltage sources with a

short circuit and current sources with an open circuit.

2) Find the Thevenin voltage, Vth by removing the load resistor from the circuit.

3) Draw the Thevenin equivalent circuit as in Figure 2(a).

4) Find the load current, iL flowing through the load resistor by using:

V th = i LR th + i LR L

= i L(R th + R L)

L = V th
i
(Rth + RL)