Maximum Average Power Transfer

Maximum Average Power is transferred from a source to a load, the load impedance should be chosen equal to the conjugate of the Thevenin equivalent impedance representing the reminder of the network.

Maximum power transfer theorem is explained by the figure. Let a network consisting of one or more independent sources and other resistive elements be represented by its Thevenin's equivalent circuit.  We find out now the value of load resistance for which the power transferred to it is the maximum.

The average power dissipated in the load is the square of the current multiplied by the resistive portion (the real part)   of the load impedance.