Permeability (electromagnetism)

2016-06-28T16:23:23Z

138.231.71.53: The value of µ0 is 4E-7\pi, this is how it is defined.

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'''Permeability''' is a [[property]] of a material that describes how [[density|dense]] a [[magnetism|magnetic field]] would be if the same amount of [[electric current|current]] was passed through it. Permeability is measured in henries per [[metre]] (H/m) and its symbol is <math>\mu</math>.

Since [[vacuum|empty space]] has a [[constant]] permeability (called the '''permeability of free space''' or <math>\mu_{0}</math>) of exactly <math>0.0000004 \times \pi</math>, most materials are listed with a ''relative permeability'' (symbol <math>\mu_{r}</math>). Relative permeability is the permeability of the material divided by the permeability of free space (<math>\mu_{r} = \mu / \mu_{0}</math>). The permeability of most materials is very close to 1. That means that the permeability of most materials is close enough that we can typically ignore it and use the permeability of free space instead.<ref>Lines and Fields in Electronic Technology, Stanley and Harrington pg 13</ref> The biggest exceptions are materials called [[ferromagnetism|ferromagnetic materials]]. Some examples are [[iron]] (5000) and [[nickel]] (600). Some materials have been specially designed to have a permeability one million times larger than empty space.<ref>http://info.ee.surrey.ac.uk/Workshop/advice/coils/mu/#mur</ref>

== References ==
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[[Category:Electromagnetism]]

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Permeability (electromagnetism)