Question

Focal length of a lens it when immersed in water.

Answer 1

refractive index for lens immersed in water is less than that of lens in air, so according to the refractive index valuefocal length will shift. in case 2 focal length is more than case 1.

Answer 2

This is because the focal length of mirrors does not depend on the external medium in which it is held. In case of lenses, refraction takes place. When a lens is immersed in water, the value of refractive index decreases. Hence its focal lengthincreases.
HOPE IT IS HELPFUL
PLEASE MARK IT AS BRAINLIEST