Maximum power transfer theorem may be stated as
A resistive load will abstract maximum power from a network when the load resistance is equal to resistance of the network as viewed from the output terminals with all other energy source removed leaving behind their internal resistance.
In the given fig is a G/R, Rg is internal resistance, R is a resister connect in series with the Rg.
Total internal resistance of the circuit.
Ri = Rg + R
Ri = RL
Then RL will be maximum power from the circuit we know that
Where Vs is the voltage source
The power delivered to the load
Pi = PL
PL= VL IL