The rate at which electric work is done by the source of emf in maintaining the current in electric circuit
Therefore Electric Power (P) = W/t =VIt/t=VI watt or joule/s
Power is said to be one watt if one ampere of current flows I it against a potential difference of 1 volt
Commercial unit of power is horse power, 1HP=746watt
It is the chemical energy of cell which supplies the power to the circuit.