# Definition:Ampere (Unit)

## Definition

The ampere is the SI base unit of electric current.

Note that, although one of the SI base units, electric current is not one of the fundamental dimensions of physics.

It is defined as being:

The constant current which will produce a force of attraction whose value is $2 \times 10^{–7}$ newtons per metre of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one metre apart in a vacuum.

This arises from Ampère's Force Law, which states that such an attractive force exists.

### Symbol

The symbol for the ampere is $\mathrm A$.

## Source of Name

This entry was named for André-Marie Ampère.