Question:

A thin prism P_1 of angle 4^0, and made from a glass of refractive index 1.54, is combined with another thin prism P_2 made from a glass of refractive index 1.72, to produce dispersion without deviation.

The angle of P_2 is:

(a) 5.33^0

(b) 4^0

(c) 3^0

(d) 2.6^0

Solution

For no deviation A_1(mu_1-1) = A_2(mu_2-1)

A_1 = 4^0, mu_1 = 1.54 and mu_2 = 1.72

=> 4 (1.54-1)= A_2(1.72-1)

=> A_2 = (40\ xx0.54)/0.72 = (4xx54)/72= 3^0

Therefore, option (c) is correct.