The velocity of electromagnetic radiation in a medium of permittivity ${\mathrm{\epsilon }}_0$ and permeability ${\mathrm{\mu }}_0$ is given by

Velocity of electromagnetic radiation is the velocity of light (c), i.e.,

$\mathrm{c}=\frac{1}{\sqrt{{\mathrm{\mu }}_0{\mathrm{\epsilon }}_0}}$

Where ${\mathrm{\mu }}_0$ is the permeability and ${\mathrm{\epsilon }}_0$ is the permittivity of free space.