Question

The ratio of thickness of plates of two transparent media $A$ and $B$ is $6:4$ . If light takes equal time in passing through them, then the refractive index of medium $B$ with respect to medium $A$ will be:

• A. $1.4$
• B. $1.5$
• C. $1.75$
• D. $1.33$

Answer 1

Answer: (B)

Time taken by light to travel distance $x$ through a medium of refractive index $\mu $ is
$t=\frac{\mu x}{c}\Rightarrow \frac{\mu _{B}}{\mu _{A}}=\frac{x_{A}}{x_{B}}=\frac{6}{4}\Rightarrow _{A}\mu _{B}=\frac{3}{2}=1.5$