Question

Determine time taken for the sunlight to pass through a window glass of 5 mm thickness when incident normally. $({\mu }_{glass}=1.5)$

• A. $2.5\times {10}^{-11}s$
• B. $3.5\times {10}^{-7}s$
• C. $3.5\times {10}^{-11}s$
• D. $2.5\times {10}^{-7}s$

Answer 1

The correct option is A $2.5\times {10}^{-11}s$

Since , we know that
$\mu =\frac{speedoflightinvaccum}{speedoflightinmedium}$
So speed of light in glass $=\frac{3/{10}^8}{1.5}=2/{10}^8\frac{m}{s}$
So, time taken by the light ray to cover 5mm thickness in glass is
$t=\frac{5/{10}^{-3}m}{2/{10}^8\frac{m}{s}}=2.5/{10}^{-11}s$