The amount of work done or energy expended per unit of time is called power. The algebraic expression for power is
Where ΔW is the energy expended in a time interval Δt.
The SI unit of power is called the watt (W) and it is defined as a rate of transfer of energy of 1 Joule per second. Thus 1 watt = 1 Joule /sec =107 ergs/s. Larger units used are the kilowatt (KW) and the megawatt(MW).
1KW = 1000 W
1 MW = 1000000W.
