Volt
The volt is the SI derived unit for electric potential and voltage (derived from the ampere and watt). It is named in honor of Alessandro Volta, who, in 1800, invented the voltaic pile, the first chemical battery.
The volt is defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power. Hence, it is has the base SI representation m2 · kg · s-3 · A-1, which can be equally represented as one joule of energy per coulomb of charge, J/C.
Since 1990 the volt is maintained internationally using the Josephson effect, where a conventional value is used for the Josephson constant, fixed by the 18th CGPM as
K{J-90} = 0.4835979 GHz/µV.
SI electricity units
| SI electromagnetism units | |||
|---|---|---|---|
| Name | Symbol | Dimensions | Quantity |
| ampere (SI base unit) | A | A | Current |
| coulomb | C | A·s | Electric charge, Quantity of electricity |
| volt | V | J/C = kg·m2·s−3·A−1 | Potential difference |
| ohm | Ω | V/A = kg·m2·s−3·A−2 | Resistance, Impedance, Reactance |
| ohm metre | Ω·m | kg·m3·s−3·A−2 | Resistivity |
| farad | F | C/V = kg−1·m−2·A2·s4 | Capacitance |
| farad per metre | F/m | kg−1·m−3·A2·s4 | Permittivity |
| reciprocal farad | F−1 | kg1·m2·A−2·s−4 | Elastance |
| siemens | S | Ω−1 = kg−1·m−2·s3·A2 | Conductance, Admittance, Susceptance |
| siemens per metre | S/m | kg−1·m−3·s3·A2 | Conductivity |
| weber | Wb | V·s = kg·m2·s−2·A−1 | Magnetic flux |
| tesla | T | Wb/m2 = kg·s−2·A−1 | Magnetic flux density |
| ampere per metre | A/m | m−1·A | magnetic induction |
| ampere-turns per weber | A/Wb | kg−1·m−2·s2·A2 | Reluctance |
| henry | H | V·s/A = kg·m2·s−2·A−2 | Inductance |
| henry per metre | H/m | kg·m·s−2·A−2 | Permeability |
| (dimensionless) | - | - | Magnetic susceptibility |
See also
Categories: SI derived units | Units of electrical potential