In physics, the Time rate of doing Work or of producing or expending Energy. The unit of power in the Metric System is the Watt, which equals 1 Joule per Second. It is also the amount of power that is delivered to a component of an Electric Circuit when a current of 1 Ampere flows through the component and a voltage of 1 Volt exists across it. The English Units of Measurement is the horsepower, which equals 550 foot-pounds per second or 746 Watts.