The rate at which an electrical machine uses electrical energy or converts it into other forms of energy—for example, light, heat, mechanical energy. Usually measured in watts (equivalent to joules per second), it is equal to the product of the voltage and the current flowing.
An electric lamp that passes a current of 0.4 amps at 250 volts uses 100 watts of electrical power and converts it into light —in ordinary terms it is a 100-watt lamp. An electric motor that requires 6 amps at the same voltage consumes 1,500 watts (1.5 kilowatts), equivalent to delivering about 2 horsepower of mechanical energy.