Find the value of R for which maximum power is transferred from source. According to maximum power transfer theorem, the maximum power is transferred when the load resistance equals the source resistance. The source resistance is given by Rin. Find the equivalent resistance of the R network. It should be equal to 4 Ohm for maximum power transfer. To verify measure the power from the V and I of the R network and find the power using V.I. Vary the resistance and verify the power value.