Question

If angle of incidence is 42° and angle of refraction is 30°, then refracted ray is deviated
by an angle:
(a) 12°
(b) 72°
(c) 1.4°
(d) sin 42°/sin 30°.
​

Answer 1

Option(a) is the correct answer.

12°

Given:

The Angle of incidence is 42°. The angle of refraction is 30°.

To find:

The angle of deviation.

Solution:

The angle of incidence(i)= 42°

The angle of refraction(e)=30°

The angle of the prism (A)=60°

This is the case of light entering the prism.

We know the relation between the angle of incidence, angle of refraction, angle of deviation, and the angle of the prism.

The angle of deviation= Angle of incidence + Angle of refraction - Angle of prism

= 42°+30°-60°

=72°-60°

=12°

So, the angle of deviation is 12°.

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