electric power

Rate at which an electrical machine uses electrical energy or converts it into other forms of energy – for example, light, heat, or mechanical energy. Usually measured in watts (equivalent to joules per second), it is equal to the product of the voltage and the current flowing.

In a closed circuit the potential difference (voltage) causes electrons to flow towards the positive potential. Work is done in moving the electrons, and the rate at which this work is done is called the electrical power. If the voltage is V volts and the current is I amps, then the power, P watts, is given by P = V × I

An electric lamp that passes a current of 0.4 amperes at 250 volts uses 100 watts of electrical power and converts it into light and heat – in ordinary terms it is a 100-watt lamp. An electric motor that requires 6 amperes at the same voltage consumes 1,500 watts (1.5 kilowatts), equivalent to delivering about 2 horsepower of mechanical power.