We can define power as the rate of doing work or simply the work done in unit time. The SI unit of power is Watt (W).

Work is defined as a force causing the movement or displacement of an object. The SI unit of work is joule (J).

We can define time as time taken to do work. The SI unit of time is seconds (s).

**Formula to calculate power from work and time.**

**Example:**

If a 60 watt bulb takes 5 seconds to light up, calculate the amount of power needed for its filament to glow.

Therefore, the amount of power needed to light up the bulb is 12 W.