Question

A ray of light passes through a glass plate of thickness $t$ and refractive index $\mu$. If the speed of light in vacuum is $c$, then the time taken by light in passing through the plate will be

• A. $\mu t$
• B. $\mu t/c$
• C. $tc/\mu$
• D. $t/\mu c$

Answer 1

The correct option is B $\mu t/c$

As $\mu =\frac{c}{v}$
$\therefore v=\frac{c}{\mu }$
Time taken $=\frac{thickness}{velocity\left(v\right)}=\frac{t}{c/\mu }=\frac{\mu t}{c}$.