Q. A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and the latter is equal to $\frac{3}{4}$the angle of prism. The angle of deviation is
A) $25{^\circ}$
B) $30{^\circ}$
C) $45{^\circ}$
D) $35{^\circ}$
Explanation
(b) It is observed if $\angle i = \angle e$ deviation produced is minimum
And $i = \frac{A\ + \ \delta_{m}}{2}$
Here $A = 60{^\circ}$
And $\angle i = \ \angle e = \frac{3}{4}\angle A$
$\delta_{m} = 2 \times \frac{3}{4} \times 60{^\circ} - 60{^\circ} = 30{^\circ}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.