Question

In given figure, a light ray AB is incident normally on one face PQ of an equilateral glass prism. Find out the angles at faces PQ and PR. 

A. 60° B. 30° C. 45° D. 90°

Answer 1

Angle of incidence, i = 0° 

Angle of refraction, r = sin (i)×n 

Where n = refractive index 

So, r₁ = 0° 

Where, 

r₁ = angle of refraction at PQ 

r₂ = angle of incidence from inside on side PR 

A = angle of prism 

We know that 

A = r₁ + r₂ 

r₂ = A – r₁ 

= 60° – 0° 

= 60°