Question

Two rectangular slabs $\text{A}$ and $\text{B}$ through which light ray passes as shown in figure. If both slabs are identical, made by different materials and $x_A<x_B$, then





(${\mu }_A$ and ${\mu }_B$ are the refractive indices of slab $A$ and slab $B$)

• A. ${\mu }_A>{\mu }_B$
• B. ${\mu }_A<{\mu }_B$
• C. ${\mu }_A={\mu }_B$
• D. Cannot say

Answer 1

The correct option is A ${\mu }_A>{\mu }_B$

Since incident angle and emergent angle in both slabs are same and $x_A<x_B$.

So, $i_A<i_B$

From Snell's law, we can write that,

$\frac{\sin i}{\sin i_A}=\frac{{\mu }_A}{\mu }..........\left(1\right)$

(where $\mu$ is the refractive index of air)

Similarly,

$\frac{\sin i}{\sin i_B}=\frac{{\mu }_B}{\mu }..........\left(2\right)$

From eq $\left(1\right)$ and $\left(2\right)$

${\mu }_A\sin i_A={\mu }_B\sin i_B$

${\mu }_A>{\mu }_B(\because i_A<i_B)$

Hence, option (a) is the correct answer.

Why this question? This question will check the basic understanding of student regarding the concept of bending of light when a light ray travels from one medium to another.