Question

What should be the angle of incidence for a ray of light which suffers a minimum deviation of 36° through an equilateral prism?

[Hint: A = 60°, i = (A + δ_min)/2]

Answer 1

Given, 

Angle of prism, A = 60° 

Angle of minimum deviation, δ_min  = 36°

Angle of incidence, i = ?

As  δ_min  = 2i - A

36° = 2i - 60°

i = 48°