MAXIMUM POWER TRANSFER
In many practical situations, a circuit is designed to provide power to a load. There are applications in areas such as communications where it is desirable to maximize the power delivered to a load. The Thevenin equivalent is useful in finding the maximum power a linear circuit can deliver to a load. We assume that we can adjust the load resistance RL. If the entire circuit is replaced by its Thevenin equivalent except for the load, as shown in figure, the power delivered to the load is
Showing that the maximum power transfer takes place when the load resistance RL equals the Thevenin resistance Rth.