Question

A layer of benzene $(\mu =1.5)$ having thickness $12\text{cm}$ floats in a vessel on water layer $(\mu =4/3)$ having thickness $8\text{cm}$. When viewed from top obliquely, the apparent depth of the bottom of the vessel below the surface of benzene will be

• A. $18\text{cm}$
• B. $16\text{cm}$
• C. $14\text{cm}$
• D. $12\text{cm}$

Answer 1

The correct option is C $14\text{cm}$


For the multiple media of different refractive index,
Apparent depth,
$d_{\text{app}}=\frac{t_1}{{\mu }_1}+\frac{t_2}{{\mu }_2}$
$\Rightarrow d_{\text{app}}=\frac{12}{1.5}+\frac{8}{4/3}=14\text{cm}$
Thus, the bottom of the vessel will appear at a depth of $14\text{cm}$.

Why this question? It tests your understanding of apparent depth, when more than one media is present.