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The **permeability of free space**, **μ _{0}**, is a physical constant used often in electromagnetism. It is defined to have the exact value of 4π x 10

It is related to the speed of light by the equation:

where

- [math]c[/math] is the speed of light and
- [math]\epsilon_0[/math] is the permittivity of free space.

A magnetic field, [math]B[/math] in a region of space has field energy associated with it. That energy density is defined as:^{[2]}

One particular use is the magnetic force. The constant gives how strong the force is between two electric currents separated by a distance:^{[1]}

where

- [math]F[/math] is the Magnetic force,
- [math]I_1[/math] and [math]I_2[/math] are two currents, and
- [math]r[/math] is the separation between the wires carrying the currents.

Visit Hyperphysics for more information on this constant.

For further information please see the related pages below:

- ↑
^{1.0}^{1.1}Hyperphysics. (August 28, 2015).*Electric field*[Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elefie.html - ↑ Jackson, John David (1998). Classical Electrodynamics (3rd ed.). New York: Wiley. p. 213

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Kailyn Stenhouse, Jordan Hanania, Bethel Afework, Jason Donev

Last updated: June 4, 2018

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