Question

Time taken by the sunlight to pass through a slab of $4cm$ and refractive index $1.5$ is ______ s.

• A. $2\times {10}^{10}$
• B. $2\times {10}^{-8}$
• C. $2\times {10}^{80}$
• D. $2\times {10}^{-10}$

Answer 1

The correct option is D $2\times {10}^{-10}$

$d=4cm$
$\mu =1.5$
$\mu =\frac{c}{v}\Rightarrow v=\frac{c}{\mu }=\frac{3\times {10}^8}{1.5}=2\times {10}^{8}m/s$
time $t=\frac{d}{v}=\frac{4\times {10}^{-2}}{2\times {10}^8}=2\times {10}^{-10}second$