**coulomb**

##### SI coherent derived unit with special name and symbol

Name | Symbol | Derived quantity | Expressed in terms of SI base units | |

coulomb | C | electric charge | s A | |

## DefinitionThe coulomb, symbol C, is the SI coherent derived unit of electric charge. One coulomb is the charge transported by a constant current of one ampere in one second. |

The coulomb is named after the French physicist, Charles-Augustin de Coulomb (1736 – 1806).

The fixed numerical value of the elementary charge, *e*, is defined as 1.602 176 634 × 10^{−19} C. This definition implies the exact relation *e* = 1.602 176 634 × 10^{−19} C. Inverting this relation gives an exact expression for the coulomb in terms of the defining constant *e*:

The effect of this definition is that one coulomb is exactly 1/(1.602 176 634 × 10^{−19}) of the value of the elementary charge, *e*.

### Capacitance

One coulomb is the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt.