Question

Time taken by sunlight to pass through a window of thickness $ 4 \,mm $ whose refractive index is $ \frac{3}{2} $ is:

• A. $ 2\times {{10}^{-4}}s $
• B. $ 2\times {{10}^{4}}s $
• C. $ 2\times {{10}^{-11}}s $
• D. $ 2\times {{10}^{11}}s $
• E. $ 2\times {{10}^{8}}s $

Answer 1

Answer: (C)

Time taken $ =\frac{\mu t}{c} $
$ =\frac{\frac{3}{2}\times 4\times {{10}^{-3}}}{3\times {{10}^{8}}} $
$ =2\times {{10}^{-11}}s $