Question

The converging or diverging power of a lens depends upon the difference of refractive index of lens with respect to the medium in which it is placed. If a converging lens having power P is immersed in a liquid, its focal length

• A. Will increase
• B. Will decrease
• C. Will remains unchanged
• D. May decrease or may increase

Answer 1

The correct option is D May decrease or may increase

According to the lens maker’s formula,
$\frac{1}{f}=\left(\frac{{\mu }_2}{{\mu }_1}-1\right)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)$So, the focal length of the lens will increase or decrease, depending upon the refractive index of liquid $\left({\mu }_1\right)$.
Hence, the correct answer is option (d).