If ε0 and µ0 are the electric permittivity and magnetic

If ε₀ and µ₀ are the electric permittivity and magnetic permeability in vacuum, ε and µ are corresponding quantities in medium, then refractive index of the medium is

We know that velocity of electromagnetic wave in vacuum

v₀ =	1
	√μ₀∊₀

and velocity of electromagnetic wave in medium is

v =	1
	√μ∊

Therefore refractive index of the medium

(μ) =	Vel of E.M. wave in medium (v₀)
	Vel of E.M. wave in medium (v)

=	1/√μ₀∊₀
	1/√μ∊