Optics Question 746

Question: Time taken by the sunlight to pass through a window of thickness 4 mm whose refractive index is 1.5 is

[CBSE PMT 1993]

Options:

A) $ 2\times {{10}^{-8}} $ sec

B) $ 2\times 10^{8} $ sec

C) $ 2\times {{10}^{-11}} $ sec

D) $ 2\times 10^{11} $ sec

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Answer:

Correct Answer: C

Solution:

Velocity of light in the window = $ \frac{3\times 10^{8}}{1.5}m{{s}^{-1}} $

$ =2\times 10^{8}m{{s}^{-1}} $

Hence $ t $ = $ \frac{4\times {{10}^{-3}}}{2\times 10^{8}}s=2\times {{10}^{-11}}s $



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