An equilateral prism made of a material of refractive index 2 is completely immersed in a transparent liquid of refractive index 2 . A ray of monochromatic light is incident on one face of the prism such that the refracted ray inside the prism travels parallel to its base. What is the angle of incidence of the ray at the prism face?

Step-by-step solution

For an equilateral prism, the angle of the prism is A = 60^ . When the refracted ray inside the prism is parallel to its base, the prism is in the position of minimum deviation. In this position, the angle of refraction at the first face is r = A 2 = 60^ 2 = 30^ . Applying Snell's law at the first refracting surface, we use the relative refractive index of the prism with respect to the surrounding liquid: _ liquid i = _ prism r Substituting the given values ( _ liquid = 2 , _ prism = 2 ): 2 i = 2 30^ 2 i = 2 1 2 =