If in a plano-convex lens the radius of curvature of the convex surface is 10 cm and the focal length of the lens is 30 cm then the refractive index of the material of lens will be

Q. If in a plano-convex lens the radius of curvature of the convex surface is 10 cm and the focal length of the lens is 30 cm then the refractive index of the material of lens will be :

A.            1.33

B.            3

C.            1.66

D.            1.5

Answer: 1.33