Electric power is measured in the same way as is water power. Water power is equal to the quantity of water in pounds that falls per minute multiplied by the "head" or "drop" in feet.

Electric power is equal to the intensity of current in amperes multiplied by the pressure in volts. The unit of electric power is a watt. A watt is the power given by a current of one ampere flowing with a pressure of one volt.

The watt is a very small unit, so that the kilowatt (1000 watts) is generally used. Electricity is measured by the number of kilowatts used per hour. To illustrate: If an electric generator gives 14 kw. for 9 hrs., it produces 126 kilowatt-hours of work.