In many practical situations, a circuit is designed to provide power to a load. We now address the problem of delivering the maximum power to a load when given system with known internal losses. It should be noted that this will result in significant internal losses greater than or equal to the power delivered to the load.
Maximum power is transferred to the load when the load resistance equals the Thevenin resistance as seen from the load (RL = RTh).
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 id replaced by its Thevenin equivalent except for the load, the power delivered to the load is: