Volt
The volt (symbol: V) is the SI unit of electric potential difference and electromotive force. It is named after the Italian physicist Alessandro Volta (1745–1827).
A similar unit, used for practical measurements of potential difference, is the conventional volt (symbol: V90).[note 1] The 2006 CODATA recommended value for V90 is:[1]
- V90 = (KJ–90/KJ) V = [1 + 1.9(2.5) × 10−8] V
The international volt (symbol: Vint) is now obsolete.
Contents
Definition
The volt is defined as the potential difference between two points on a conductor when the current flowing is one ampere and the power dissipated is one watt:[2] from the usual laws of electromagnetism, this implies that the volt is one watt per ampere:
- 1 V = 1 W A−1
Several equivalent definitions can be constructed, for example one volt is one ampere ohm, a historically important definition which derives from Ohm's law. Equally, one volt is one joule per coulomb, which gives the electronvolt as a convenient unit of energy at the atomic scale.
- 1 V = 1 A Ω = 1 J C−1 = 1 kg m2 A−1 s−3
Conventional volt
Realization
History
Notes and references
Notes
- ↑ V90 is considered to be a physical constant, hence the use of italics for the symbol.
References
- ↑ Mohr, Peter J.; Taylor, Barry N.; Newell, David B. CODATA Recommended Values of the Fundamental Physical Constants: 2006. Rev. Mod. Phys. 2008, 80 (2), 633–730. doi:10.1103/RevModPhys.80.633, <http://physics.nist.gov/cuu/Constants/codata.pdf>.
- ↑ CIPM (1946), Resolution 2.
External links
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See also the corresponding article on Wikipedia. |
- volt at Sizes.com
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