Watt
lastmod 2025-11-05created 2020-09-228 edits
One watt (symbol W) is the SI unit of power, equal to 1 joule (N·m) per second. It is named after James Watt, who contributed to improving the steam engine, and was adopted at the general meeting of the British Association for the Advancement of Science in 1889.
Simple brief
It refers to the amount of electric power, and its unit is the watt (W).
Voltage(V)XCurrent(A)=Power(W)
Definition
\(1~\rm{W} = 1~\dfrac{\rm{J}}{\rm{s}} = 1~\dfrac{\rm{N\cdot m}}{\rm{s}} = 1~\dfrac{\rm{kg} \cdot \rm{m^2}}{\rm{s^3}} = \mathrm{1 ~ V \cdot 1 ~ A}\)
1W * 3,600s = 1J/s * 3,600s = 3,600J = 1Wh
W (watt) is the unit of power for doing 1J (joule) of work in 1 second, and multiplying this by 3,600 seconds (1 hour) gives the electrical energy unit watt-hour (Wh).
By the definitions of the ampere and volt units, when 1 ampere flows through a potential difference of 1 volt, work is done at a rate of 1 watt.
Volt/Ampere/Watt relationship
Volt
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- For example, here are 3 waterfalls with different widths and heights.
- Waterfall 2, which is wider, has more force than waterfall 1 of the same height. (difference in A)
- Between waterfalls 2 and 3, which have the same width, waterfall 3, which is higher, has more force. (difference in V)
Ampere
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- Filling a 100-liter water tank through a 1 cm diameter pipe at a pressure (V) of 10 (①) takes 10 seconds.
- Increasing the pressure (V) to 20 would take 5 seconds, and widening the diameter to 2 cm also takes 5 seconds (②).
- When filling the same amount of water in the same time, pressure (V) and diameter (A) are inversely proportional.
- On the other hand, if the goal is simply to fill it as fast as possible regardless of time, you would raise both the pressure and the diameter. (③)
Watt
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Categories
See also
- Adapter
- Electrical cable
- P: Korean: 전력 (Korean: 와트, W, Watt)
- V: Korean: 전압 (Korean: 볼트, V, Volt)
- I: Korean: 전류 (Korean: 암페어, A, Ampere)