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
Show Answer
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 $
