If the critical angle for total internal reflection from a medium to vacuum is 45 ° , then velocity of light in the medium is,

Step-by-step solution

Use the concept of critical angle in terms of the refractive index of a medium with respect to another medium, sin θ C = 1 μ , ⇒ μ = 1 sin θ C = 1 sin 45 ° = 1 ( 1 / 2 ) = 2 , now we know that the ratio of the speed of light in vacuum and speed of light in a medium is called the refractive index of the medium, μ = c v ⇒ v = c μ = 3 × 10 8 2   m   s - 1 .