Question

The time required by a ray of light to travel through a glass slab of thickness $2mm$ and refractive index $1.5$will be

• A. ${10}^{-8} s$
• B. ${10}^{-10} s$
• C. ${10}^{-12} s$
• D. $2\times {10}^{-8} s$

Answer 1

The correct option is B

${10}^{-10} s$

Step 1: Given Data

Refractive index of glass ${\mu }_g=1.5$

Thickness $d=2 cm=2\times {10}^{-2}m$

Step 2: Calculate the time taken:

We know that $velocity=\frac{dis\tan ce}{time}$ here the thickness of the glass slab will be the distance traveled by the light.

$\text{time(}t)=\frac{d}{v}\text{and}v=\frac{c}{\mu }$where c is the speed of light in a vacuum

So, $t=\frac{d\mu }{c}=\frac{2\times {10}^{-2}\times 1.5}{3\times {10}^8}={10}^{-10}s$

Hence, the correct option is (b) ${10}^{-10} s$