A parallel beam of light is incident from air at an angle $\alpha$ on the side PQ of a right angled triangular prism of refractive index $n = \sqrt{2}$ . Light undergoes total internal reflection in the prism at the face PR when $\alpha$ has a minimum value of ${45}^{o} .$ The angle $\theta$ of the prism is:

Question

A parallel beam of light is incident from air at an angle

\alpha

on the side PQ of a right angled triangular prism of refractive index

n = \sqrt{2}

. Light undergoes total internal reflection in the prism at the face PR when

\alpha

has a minimum value of

{45}^{o} .

The angle

\theta

of the prism is:
A parallel beam of light is incident from air at an angle α on the side PQ of a right angled triangular prism of

Quantrex Academy · Accepted Answer

Correct answer: A. 15 ^ o

1sin 45 ^ o = 2 sin r _ 1 r _ 2 - r _ 1 = θ θ = 45 ^ o - 30 ^ o ⇒ θ = 15 ^ o

A parallel beam of light is incident from air at an angle α on the...