# Definition:Ampere (Unit)

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## Definition

The ampere is the SI base unit of electric current.

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

$\mathrm A$

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

Its $\LaTeX$ code is \mathrm A .

## Source of Name

This entry was named for André-Marie Ampère.