Question

A transparent cube of 15 cm edge contains a small air bubble. Its apparent depth when viewed through one face is 6 cm and when viewed through the opposite face is 4 cm. Then the refractive index of the material of the cube is

• A. 2
• B. 2.5
• C. 1.6
• D. 1.5

Answer 1

The correct option is D 1.5

When viewed from face (1)

$\mu =\frac{u}{v}=\frac{x}{v}=\frac{x}{6}......\left(i\right)$
Now when viewed from face (2)
$\mu =\frac{15-x}{v}=\frac{15-x}{4}.....\left(ii\right)$
From equation (i) and (ii) $\mu =\frac{15-6\mu }{4}\Rightarrow \mu =1.5$.