Question

An air bubble in a glass sphere $(\mu =1.5)$ is situated at a distance $3cm$ from a convex surface of diameter $10cm$. At what distance from the surface will the bubble appear?

• A. $2.5cm$
• B. $-2.5cm$
• C. $5cm$
• D. $-5cm$

Answer 1

Answer: (B)

Since refraction occurs from denser to rarer medium,
Therefore, $-\frac{{\mu }_2}{u}+\frac{{\mu }_1}{v}=\frac{{\mu }_1-{\mu }_2}{R}$
$-\frac{3}{2\left(-3\right)}+\frac{1}{v}=\frac{1-\frac{3}{2}}{-5}=\frac{1}{10}$ or
$\frac{1}{v}=\frac{1}{10}-\frac{1}{2}=-\frac{4}{10}$
$\Rightarrow v=-2.5cm$