Principe purpose of this lecture is to present on how to measure Power. The rate of doing work is called as power or the rate at which work is done or energy is transferred is called as power. In the British system, work is expressed in foot-pounds, and the unit of power is the foot-pound per second. A larger unit called the horsepower (hp) is also used: 1 hp = 550 ft.lb/s = 33,000 ft.lb/min. The units of power can be used to define new units of work and energy. The kilowatt-hour (kWh) is the usual commercial unit of electrical energy. One kilowatt-hour is the total work done in 1 hour (3600 s) when the power is 1 kilowatt (103 J/s).