Ray Optics and Optical Instruments - Result Question 8

8. In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction?

[2019]

(a) $180^{\circ}$

(b) $0^{\circ}$

(c) equal to angle of incidence

(d) $90^{\circ}$

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Answer:

Correct Answer: 8. (d)

Solution:

  1. (d) For total internal reflection when $i=i_c$, then

refracted ray grazes with the surface. That means the angle of refraction $r=90^{\circ}$.