MAXIMUM POWER TRANSFER THEOREM In many electrical and electronic applications, we are interested in the amount of power received by a particular load (speaker, electric motor, antenna) Electric systems are a source of power and a load connected to that source Sources – Amplifiers, generators, power supplies All linearly constructed sources can be reduced to their Thevenin equivalent In DC circuits, the load can be represented by a resistance RL Maximum Power Transfer Theorem

POWER DELIVERED TO LOAD The source develops a voltage VL across the load and enables current IL to flow into it The power delivered to the load resistance (RL) depends on the value of RL Maximum Power Transfer Theorem

MAXIMUM POWER, CURRENT AND VOLTAGE CONDITIONS Maximum current IL occurs when RL = 0 (shorted terminals) The maximum voltage VL occurs when RL =  (open circuited terminals) Yet load power PL = 0 for both cases PL is maximum when RL equals the Thevenin equivalent resistance of the source, I.e. when RL = RTH The maximum power transfer theorem is thus: Maximum power is developed in a load when the load resistance equals the Thevenin resistance of the source to which it is connected Maximum power is delivered when VL = ETH/2 Thus Maximum Power Transfer Theorem