Page 192 - Basic Electrical Engineering

or, R = R i
L

Thus, maximum power transfer will occur when the value of the load

resistance is equal to the internal resistance of the source.
The maximum power transfer theorem is stated as follows:

In a dc network maximum power will be consumed by the load or
maximum power will be transferred from the source to the load when the
load resistance becomes equal to the internal resistance of the network as

viewed from the load terminals.
The value of maximum power when R = R is calculated as
L
i

When a complex dc network is to be analysed for maximum power transfer,
the circuit can first be converted into a voltage source with one internal

resistance by applying Thevenin’s theorem.
Let us take a few specific problems to understand this theorem.

Example 2.32 A 12 V battery is supplying power to a resistive load R L
through a network as shown in Fig. 2.101. Calculate at what value of R L

power transferred to the load will be maximum and what would be the value
of that maximum power.