# Definition:Abampere

## Definition

The abampere is the CGS unrationalised electromagnetic base unit of electric current.

It is defined as being:

The constant current which will produce a force of attraction whose value is $2$ dynes per centimetre of length between two straight, parallel conductors of infinite length and of infinitesimal circular cross-section placed one centimetre apart in a vacuum.
$\mathbf F \propto \dfrac {2 I_1 I_2} r$

where:

$I_1$ and $I_2$ denote the current through the two conductors
$r$ denotes the distance between the two conductors.

In the CGS unrationalised electromagnetic system, the constant of proportion is taken to be $1$, hence:

$\mathbf F = \dfrac {2 I_1 I_2} r$

### Symbol

$\mathrm {abA}$

The symbol for the abampere is $\mathrm {abA}$.

Its $\LaTeX$ code is \mathrm {abA} .

## Also known as

The abampere is also known as:

the electromagnetic unit, abbreviated $\mathrm {e.m.u.}$
the biot, abbreviated $\mathrm {Bi}$, for Jean-Baptiste Biot.

## Source of Name

This entry was named for André-Marie Ampère.

## Linguistic Note

The word abampere is a shortened form of absolute ampere, as evolved from its original full name absolute electromagnetic cgs unit of current.