Ampere

The SI unit of Electric current

The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce a force between the conductors equal to 2x10^-7 newton per metre of length.

The official symbol is A.

Named after the French physicist André-Marie Ampère (1775-1836), one of the pioneers in studying electricity.

The other electrical units are all defined in terms of the ampere:

• One ampere represents a current flow of one coulomb of charge per second.


One ampere of current results from a potential distribution of one volt per ohm of resistance.

See also: Abampere, Ammeter, Ampere Andre Marie, Current, Current Density, Kirchoffs Law, Newton, SI Units, Statampere, Voltampere (VA).