Permeability

Related physics
Free Space impedance $$Z_0 $$ as connection of permeability $$\mu_0$$ and permittivity $$\epsilon_0$$.

$$ \mu_0=4 \pi \cdot \10^{-7} N/A^2$$. The unit of $$\mu_0$$ is $$Newton/Ampere^2 N/A^2 = kg m/s^2 1/A^2$$

$$\epsilon_0=\frac{1}{\mu_0 c^2} = 8.854 \cdot \10^{-12} F/m$$. The unit of $$\epsilon_0$$ is Farad/m: $$F/m = A s/V = A^2 s^4/(kg m^2)$$