# Volt

Volt
Josephson junction array chip developed by the National Bureau of Standards as a standard volt
Unit information
Unit system SI derived unit
Unit of Electric potential, electromotive force
Symbol V
Named after Alessandro Volta
In SI base units: kg· m2· s−3· A−1

The volt (symbol: V) is the derived unit for electric potential, electric potential difference ( voltage), and electromotive force. [1] It is named after the Italian physicist Alessandro Volta (1745–1827).

## Definition

One volt is defined as the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. [2] It is also equal to the potential difference between two parallel, infinite planes spaced 1 meter apart that create an electric field of 1 newton per coulomb. Additionally, it is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it. It can be expressed in terms of SI base units ( m, kg, s, and A) as

${\displaystyle {\text{V}}={\frac {\text{potential energy}}{\text{charge}}}={\frac .}$

It can also be expressed as amperes times ohms (current times resistance, Ohm's law), watts per ampere (power per unit current, Joule's law), or joules per coulomb (energy per unit charge), which is also equivalent to electronvolts per elementary charge:

${\displaystyle {\text{V}}={\text{A}}{\cdot }\Omega ={\frac {\text{W}}{\text{A}}}={\frac {\text{J}}{\text{C}}}={\frac {\text{eV}}{e}}.}$

### Josephson junction definition

The " conventional" volt, V90, defined in 1988 by the 18th General Conference on Weights and Measures and in use from 1990, is implemented using the Josephson effect for exact frequency-to-voltage conversion, combined with the caesium frequency standard. For the Josephson constant, KJ = 2e/h (where e is the elementary charge and h is the Planck constant), the "conventional" value KJ-90 is used:

${\displaystyle K_{\text{J-90}}=0.4835979\,{\frac {\text{GHz}}{\mu {\text{V}}}}.}$

This standard is typically realized using a series-connected array of several thousand or tens of thousands of junctions, excited by microwave signals between 10 and 80 GHz (depending on the array design). [3] Empirically, several experiments have shown that the method is independent of device design, material, measurement setup, etc., and no correction terms are required in a practical implementation. [4]

Other Languages
Afrikaans: Volt
Alemannisch: Volt
العربية: فولت
aragonés: Volt
অসমীয়া: ভল্ট
asturianu: Voltiu
azərbaycanca: Volt
বাংলা: ভোল্ট
Bân-lâm-gú: Bó͘-lú-to͘h
беларуская (тарашкевіца)‎: Вольт
български: Волт
བོད་ཡིག: ཝོལ།
bosanski: Volt
brezhoneg: Volt
català: Volt
čeština: Volt
dansk: Volt
Deutsch: Volt
eesti: Volt
Ελληνικά: Βολτ
español: Voltio
Esperanto: Volto
euskara: Volt
فارسی: ولت
Fiji Hindi: Volt
français: Volt
furlan: Volt
Gaeilge: Volta
galego: Volt

한국어: 볼트
हिन्दी: वोल्ट
hrvatski: Volt
Ido: Volto
Bahasa Indonesia: Volt
interlingua: Volt
íslenska: Volt
italiano: Volt
עברית: וולט
къарачай-малкъар: Вольт
ქართული: ვოლტი
Kiswahili: Volti
Kreyòl ayisyen: Vòlt
Kurdî: Volt
Latina: Voltium
latviešu: Volts
lietuvių: Voltas
Limburgs: Volt (einheid)
magyar: Volt
македонски: Волт
മലയാളം: വോൾട്ട്
मराठी: व्होल्ट
مصرى: فولت
Bahasa Melayu: Volt
монгол: Вольт (нэгж)
မြန်မာဘာသာ: ဗို့
Nederlands: Volt (eenheid)
नेपाल भाषा: भोल्त
Nordfriisk: Volt
norsk: Volt
norsk nynorsk: Volt
occitan: Vòlt
oʻzbekcha/ўзбекча: Volt
پنجابی: وولٹ
Patois: Vuolt
Piemontèis: Vòlt
polski: Wolt
português: Volt
română: Volt
русский: Вольт
Scots: Volt
shqip: Volti
sicilianu: Volt
Simple English: Volt
slovenčina: Volt
slovenščina: Volt
српски / srpski: Волт
srpskohrvatski / српскохрватски: Volt
suomi: Voltti
svenska: Volt
Tagalog: Bolt
தமிழ்: வோல்ட்டு
tarandíne: Volt
татарча/tatarça: Вольт
తెలుగు: వోల్ట్
ไทย: โวลต์
Türkçe: Volt
українська: Вольт
vèneto: Volt
Tiếng Việt: Vôn
Winaray: Boltahe

žemaitėška: Vuolts