# Definition:Abampere

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## 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.

By Force between Infinite Parallel Straight Conductors carrying Steady Current, we have:

- $\mathbf F \propto \dfrac {2 I_1 I_2} r$

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**.