Question

A lens behaves as a converging lens in air and as a diverging lens in water. The refractive index of the material is

• A. Equal to unity
• B. Equal to $1.33$
• C. Between unity and $1.33$
• D. Greater than $1.33$

Answer 1

The correct option is C Between unity and $1.33$

For a converging lens, ${\mu }_l>{\mu }_a$ for a diverging lens, ${\mu }_l>{\mu }_w$
$\therefore {\mu }_l$ lies between ${\mu }_a$ and ${\mu }_w$ i.e. $1$ and $1.333$.