# Biot (unit)

Physical unit
Unit name Biot
Unit symbol ${\ displaystyle \ mathrm {Bi}}$
Physical quantity (s) Amperage ; magnetic flooding
Formula symbol ${\ displaystyle I; \, \ Theta}$
dimension ${\ displaystyle {\ mathsf {L ^ {1/2} M ^ {1/2} T ^ {- 1}}}}$
system Electromagnetic CGS unit system
In SI units ${\ displaystyle \ mathrm {1 \, Bi \ sim 10 \; A}}$
Named after Jean-Baptiste Biot

The biot ( unit symbol  Bi, after the French physicist Jean-Baptiste Biot ), also Abampere  (abA), is a non- legal unit of electrical current strength . It is part of the electromagnetic cgs unit system  (EMU).

Abampere is not to be equated with the designation "absolute ampere", which is used for today's SI unit amperes .

${\ displaystyle 1 \ {\ text {Biot (Bi)}} = 1 \ {\ text {Abampere (abA)}} \ {\ mathrel {\ hat {=}}} \ 10 \ {\ text {Ampere (A )}}}$

## definition

A biot is defined by the Lorentz force between two parallel, straight, infinitely long conductors with negligible cross-sections in a vacuum , similar at times to the ampere (now replaced): The strength of the current that is constant over time is 1 Bi if there is a distance of 1 cm between the conductors a force of 2  dynes per centimeter of conductor length acts from each other .

## Conversions

In addition to the EMU system, there are other variants of the cgs system, e.g. B. the electrostatic cgs system  (ESU). In the ESU system, the unit of electrical current strength is not Biot or Abampere, but static amps, whereby the current strength has a different definition and dimension . The conversion between biot and statampere therefore depends on the respective size . A current strength can be converted by multiplying it with the speed of light in a vacuum:

${\ displaystyle 1 \ {\ text {Bi}} = 1 \ {\ text {abA}} \ sim 2 {,} 998 \ cdot 10 ^ {8} \ {\ text {Statampere (statA)}}}$

Further conversion:

${\ displaystyle \ mathrm {1 \ Bi = 4 \ \ pi \ Gb}}$

with for the cgs unit Gilbert . ${\ displaystyle \ mathrm {Gb}}$

## Individual evidence

1. ^ A b Herbert Arthur Klein: The Science of Measurement: A Historical Survey . Courier Corporation, 2012, ISBN 0-486-14497-6 , pp. 431 ( limited preview in Google Book search).