Last edited 01 Feb 2019


Electricity pylons.jpg

A watt (W) is a unit of electrical power. Power is the rate at which physical work of some kind is done, or the amount of energy that is transferred per unit of time. It involves a physical system changing over a specified time.

The watt is named after James Watt, the inventor of the steam engine condenser.

According to the International System of Units (SI), one watt is defined as the energy consumption rate of one joule per second (J/s). One watt is also defined as the current flow of one ampere with a voltage of one volt.

Table of unit prefixes of watt:

(P = power)

Picowatt pW 1pW = 10^-12 W P = 10 pW
Nanowatt nW 1nW = 10^-9 W P = 10 nW
Microwatt μW 1μW = 10^-6 W P = 10 μW
Watt W P = 10 W
Kilowatt kW 1kW = 10^3 W P = 2 kW
Megawatt MW 1MW = 10^6 W P = 5 MW
Gigawatt GW 1GW = 10^9 W P = 5 GW

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