A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3 / 4 of the angle of the prism. The angle of deviation is

Question

A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3 / 4 of the angle of the prism. The angle of deviation is (A) 45° (B) 39° (C) 20° (D) 30°

Tardigrade Admin · Accepted Answer

Given i=e=(3/4) A=(3/4) × 60=45° In the position of minimum deviation 2 i=A+δm or δm=2 i-A=90-60=30°

Q. A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to $3/4$ of the angle of the prism. The angle of deviation is

$4 5^{\circ}$

$3 9^{\circ}$

$2 0^{\circ}$

$3 0^{\circ}$

Given $i = e = \frac{3}{4} A = \frac{3}{4} \times 60 = 4 5^{\circ}$
In the position of minimum deviation
$2 i = A + δ_{m}$ or $δ_{m} = 2 i - A = 90 - 60 = 3 0^{\circ}$

Q. A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3/4 of the angle of the prism. The angle of deviation is

45∘

39∘

20∘

30∘