Question

An optical fibre is of length 2.1 kilometer.
Refractive indices of core and cladding
mererials are 1.6 and 1.4. A light ray enters the
core from one end of the fibre such that it strikes
the core - cladding interface at an angle slightly
greater than the critical angle. Time taken by
the light ray to come out of the fibre is ... micro
second.
1) 2.4 2) 4.8 3) 6.8 4)12.8
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Answer 1

Answer:

12.8

Explanation:

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