Express velocity of electromagnetic wave in a material medium in terms of `mu` and `epsi`.

Explanation

An electromagnetic wave consists of oscillating electric and magnetic field vectors produced by an accelerating charged particle.
`C=(1)/sqrt(mu_(0)epsilon_(0))`
where c= velocity of light in vacumm
`epsilon_(0)`= electrical permittivity for free space
`mu_(0)` = magnetic permeability for free space