Power is a physical quantity that indicates how much work a force does per unit of time. Power (symbol P or N) thus expresses the rate of doing work:
$$P=\frac{A}{\Delta t}$$
where,
A— work;
Δt— time interval.
The unit of measurement for power in the SI system is the watt (W). One watt is equivalent to the power expended when one joule (J) of work is done in one second (s). The unit is named after the inventor of the steam engine, James Watt, and was adopted in 1889.