## Question

A lens made of glass having refractive index 1.5 has a focal length of 50 cm in air. What will be its focal length if it is immersed in a liquid of refractive index 1.2?

### Solution

100 cm

The focal length of the lens is given by

Now, refractive index of glass with respect to liquid

= refractive index of air with respect to liquid × refractive index of glass with respect to air. That is

Focal length of the glass lens immersed in liquid is given by

…(ii)

Dividing eq. (i) by (ii), we get

#### SIMILAR QUESTIONS

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