Published by:
CGP EDU Academic Team
Published on: September 12, 2026
A light ray from air is incident (as shown in figure) at one end of a glass fiber (refractive index
) making an incidence angle of
on the lateral surface, so that it undergoes a total internal reflection. How much time would it take to traverse the straight fiber of length 1 km

Text Solution
Verified by ExpertsThe correct answer is:
D
When total internal reflection just takes place from lateral surface
, i.e., 

Time taken by light to traverse some distance in a

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