Question

If an object is placed at a distance R from the pole of first surface, then the real image is formed at a distance R from the pole of the second surface. The refractive index $\mu$ of the sphere is given by

• A. 1.5
• B. 2
• C. $\sqrt{2}$
• D. none of these

Answer 1

The correct option is B 2

Let $\mu$ be the refractive index of the second medium and 1 be of the first medium.
Then,
$\frac{\mu }{R}+\frac{-1}{R}=\frac{\mu -1}{R}$

Solving for $\mu$ gives, $\mu =2$