CBSE Class 12 Physics 2019 Outside Delhi Set 1 Paper

Question : 22

Total: 27

A triangular prism of refracting angle 60∘ is made of a transparent material of refractive index ‌

√3

.
A ray of light is incident normally on the face KL as shown in the figure. Trace the path of the ray as it passes through the prism and calculate the angle of emergence and angle of deviation.

Solution:

If iC is the critical angle for the prism/material,
µ‌=‌

sin‌iC

∴‌‌sin‌iC‌=‌

=‌

√3

⇒‌‌iC‌=60∘

Angle of incidence at face AC of the prism
=60∘
Hence, refracted ray grazes the surface AC.
⇒‌ Angle of emergence ‌=90∘
⇒‌ Angle of deviation ‌‌=30∘

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