Question

A small air bubble is trapped inside a transparent cube of side 12 cm. When viewed from one of the vertical faces, the bubble appears to be at 5 cm from it. When viewed from opposite face, it appears at 3 cm from it.

• A. The distance of the air bubble from the first face is 7.5 cm.
• B. The distance of the air bubble from the first face is 9 cm.
• C. Refractive index of the material of the cube is 2.0.
• D. Refractive index of the material of the cube is 1.5.

Answer 1

Answer: (A), (D)

The correct options are
A The distance of the air bubble from the first face is 7.5 cm.
D Refractive index of the material of the cube is 1.5.


$5=\frac{x}{\mu }\dots \dots \left(i\right)$
and $3=\frac{12-x}{\mu }\dots \dots \left(ii\right)$
Solve (i) and (ii)
$\mu =\frac{3}{2}$
and $x=7.5cm$