Definition:Vacuum Permeability

Physical Constant
The vacuum permeability is the physical constant denoted $\mu_0$ defined as:


 * $\mu_0:= \dfrac {2 \alpha h} {e^2 c}$

where:
 * $e$ is the elementary charge
 * $\alpha$ is the fine-structure constant
 * $h$ is Planck's constant
 * $c$ is the speed of light defined in $\mathrm m \, \mathrm s^{-1}$

Of the above, only the fine-structure constant $\alpha$ is a measured value; the others are defined.

It can be defined as the capability of a magnetic field to permeate a vacuum.

From Value of Vacuum Permeability, it has the value:


 * $\mu_0 = 1 \cdotp 25663 \, 70621 \, 2 (19) \times 10^{-6} \, \mathrm H \, \mathrm m^{-1}$ (henries per metre)

It can equivalently be defined as:


 * $\mu_0 := \dfrac 1 {\varepsilon_0 c^2}$

where:
 * $\varepsilon_0 $ is the vacuum permittivity defined in $\mathrm F \, \mathrm m^{-1}$ (farads per metre)
 * $c$ is the speed of light defined in $\mathrm m \, \mathrm s^{-1}$

Also known as
The vacuum permeability is also known by the terms:


 * vacuum magnetic permeability
 * permeability of free space
 * permeability of vacuum
 * magnetic constant

Also see

 * Value of Vacuum Permeability
 * Definition:Vacuum Permittivity