Convex lens made up of glass `(mu_(g)=1.5)` and radius of curvature R is dipped into water. Its focal length will be (Refractice index of water =4/3)

Convex lens made up of glass (mu_(g)=1.5) and radius of curvature R is dipped into water. Its focal length will be (Refractive index of water =4/3)

A plano convex lens is made of glass of refractive index 1.5. The radius of curvature of its convex surface is R. Its focal length is

A plano convex lens is made of glass of refractive index 1.5. The radius of curvature of its convex surface is R. Its focal length is

A plano-convex lens (focal length f_2 , refractive index mu_(2) , radius of curvature R) fits exactly into a plano-concave lens (focal length f_(1) refractive index mu_1 , radius of curvature R). Their plane surfaces are parallel to each other. Then, the focal length of the combination will be :

A plano-convex lens (focal length f_2 , refractive index mu_(2) , radius of curvature R) fits exactly into a plano-concave lens (focal length f_(1) refractive index mu_1 , radius of curvature R). Their plane surfaces are parallel to each other. Then, the focal length of the combination will be :