Watt
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)
| NAME | SYMBOL | CONVERSION | EXAMPLE |
| 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 |
| Terawatt | TW | 1TW = 10^12W | P = 5 TW |
Planning our electric future: a White Paper for secure, affordable and low-carbon electricity, Glossary, published by the Department of Energy & Climate Change on 14 July 2011, states: ‘One gigawatt of electricity from wind could meet the annual energy needs of over 600,000 UK households, around 1.5 per cent of the UK energy demand.’
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