Question

There is a small air bubble inside a glass sphere $(\mu =1.5)$ of radius $10cm$. The bubble is $4cm$ below the surface and is viewed normally from the outside the apparent depth of the bubble is :

• A. $3cm$ below the surface
• B. $5cm$ below the surface
• C. $8cm$ below the surface
• D. $10cm$ below the surface

Answer 1

The correct option is A $3cm$ below the surface

Formulae:

$\frac{{\mu }_2}{v}-\frac{{\mu }_1}{u}=\frac{{\mu }_2-{\mu }_1}{R}$

$\frac{1}{v}-\frac{1.5}{-40}=\frac{1-1.5}{-10}$

$\frac{1}{v}=\frac{0.5}{10}-\frac{1.5}{4}$

$v=-3cm$

Bubble will be 3 cm below the surface.