Question

A biconvex lens made of a transparent material of refractive index 1.5 is immersed in water of refractive index 1.33. Will the lens behave as a converging or a diverging lens? Give reason?

Answer 1

in the case of a convex lens
given refractive index of medium =1.33
Ng=1.5
Nl=1.33
Ng/Nl=1.5/1.33>1
therfore
the convex lens in this liquid behaves as convergent lens

in case of biconvex lens just the opposite takes place that is it will no behave as divergent lens as the valueis>1