Let the refractive index of a denser medium with respect to rarer medium be n 12 and its critical angle be θ C . At an angle of incidence A when light is travelling from denser medium to rarer medium, a part of the light is reflected and the rest is refracted and the angle between reflected and refracted rays is 90 o . Angle A is given by

Step-by-step solution

In accordance with Snell's law, μ = μ R μ D = sin ⁡ i c sin ⁡ 90 o here i c is the angle of incidence. μ R μ D = sin ⁡ i c μ = μ R μ D = sin ⁡ A sin ⁡ r = sin A sin 90 ° - A = sin A cos A μ R μ D = tan ⁡ A . The critical angle is related to the angle A as tan ⁡ A = sin ⁡ θ C A = tan - 1 ⁡ sin ⁡ θ C .