Question

A prism is an optical medium bounded by three refracting plane surfaces. A ray of light suffers successive refractions on passing through its two surfaces and deviates by a certain angle from its original path. The refractive index of the material of the prism is given by `mu = sin((A + deltam)/2)//sin  A/2`. If the angle of incidence on the second surface is greater than an angle called critical angle, the ray will not be refracted from the second surface and is totally internally reflected.

Three beams of red, yellow and violet colours are passed through a prism, one by one under the same condition. When the prism is in the position of minimum deviation, the angles of refraction from the second surface are r_R, r_Y and r_V respectively. Then ______.

Options

• r_V < r_Y < r_R

• r_Y < r_R < r_V

• r_R < r_Y < r_V

• r_R = r_Y = r_V

Answer 1

Three beams of red, yellow and violet colours are passed through a prism, one by one under the same condition. When the prism is in the position of minimum deviation, the angles of refraction from the second surface are r_R, r_Y and r_V respectively. Then r_R = r_Y = r_V.

Explanation:

In the scenario of minimum deviation, the refraction from the second surface for all three beams is identical. To achieve minimum deviation, the beam must be parallel to the prism's base.