What is maximum power transfer??,?
Given a supply of power with an internal resistance and a variable external load, the maximum possible power is transferred to the load when it equals the resistance of the supply. Note that the reverse is not true, because for a given load, a lower resistance supply will always transfer more power. The situation is not symmetrical because the theory is only interested in maximising load power.
Maximum power transfer is the maximum rate, often expressed in Watts, at which electrical energy can be transfered from any given electrical energy source (EMF) to a load resistance. Formula for maximum electrical energy transfer rate ----> (Resistance of load) must be made = to fixed resistance of a given electrical energy source. This can be verified by modeling a Voltage source of a given magnitude connected in series with it's own arbitrary valued internal resistance and also in series with the load resistance and observing that the load resistance value equal to the arbitrary valued internal resistance of the Voltage source is the value of load resistance at which maximum power is transfered to the load resistance. This maximum rate (Watts) occurs when the value of the load resistance is selected such that it is equal to the value of the internal resistance of the electrical energy source that is furnishing the electrical energy.
Maximum power transfer happens when the source impedance is equal to the load impedance.
To be complete, look up "conjugate matching".