Question

A ray of light falls on the surface of a spherical glass paper weight making an angle alpha with the normal and is refracted in the medium at an angle beta. The angle of deviation of the emergent ray from the direction of the incident ray is –

• A. (alpha – beta)
• B. (beta – alpha)
• C. $\frac { 1 } { 2 }$ (alpha – beta)
• D. 2 (alpha – beta)

Answer 1

Answer: (D)

2 (alpha – beta)

Answer 2

deviations at A and B are equal in magnitude and have the same order total deviation
(a - b) + (a - b) = 2(a - b)