Talk:Permeability constant

The permeability constant or magnetic constant (μ0) is the permeability of vacuum (or of free space). It is a physical constant not defined by other physical constants.

It is defined as the ratio of magnetic field density to magnetic field strength in vacuum:

In SI units, the value is exactly expressed by:

μ0 = 4π×10−7 N/A2 = 4π×10−7 H/m