Question

A ray passes through on equilateral triangle in such a way that its angle of incidence and angle of emergence are equal and this angle is 3/4 of angle of prism. Then angle of deviation will be :
(a) 45°
(b) 70°
(c) 39°
(d) 30°

Answer 1

(d) 30°
For equilateral triangle A = 60°
∴ Angle of incidence = emergent angle
So, this is condition of minimum deviation.