A convex lens made up of glass of refractive index 1.5 is dipped, in turn, in (i) a medium of refractive in dex 1.65, (ii) a medium of refractive index 1.33.
(a) Will it behave as a converging or a diverging lens in the two cases ?
(b) How will its focal length change in the two media ?

Explanation

`(1)/(f) = ( mu -1) ( ( 1)/(R_(1)) - ( 1)/( R_(2)))`
(a) (i) Diverging lens or concave lens
(ii) Converging lens or convex lens
(b) (i) Focal length will become negative nad its magnitude would increase
(ii) Focal length increases.