On entering in a medium from air, the speed of light becomes half

Reflection & Refraction (C10)

On entering in a medium from air, the speed of light becomes half of its value in air. Find the refractive index of that medium with respect to air?

Answer

Refractive Index of a medium (µ) = Velocity of light in vacuum / Velocity of light in the medium

Let the velocity of light in vacuum be v1 and velocity of light in the medium be v2.

v1/2 = v2

Hence, µ = v1/v2

= v1/(v1/2)

= 2