A concave lens has radioi of curvatures of 20 cm and 30 cm respectively. If the refrative index of the material of lens is `1.6` it focal length is given by

A biconves lens has radil of curvature 20 cm and 15 cm each. The refractive index of the material of the lens is 1.5. What is its focal length? Will the focal length change if the lens is fipped by the side?

A biconvex lens has radius of curvature 20 cm each. If the refractive index of the material of the lens is 1.5, what is its focal length?

A double convex lens has faces of radii of curvature 30 cm each. The refractive index of the material of the lens is 1.5. What is the focal length of this lens when immersed is carbondisulphide of refractive index 1.6 ?

A thin douel convex lens has surfaces of radii of curature 30 cm each.Find the refractive index of the material of lens,if the focal length is 25 cm.

The radii of curvature of both the sides of a convex lens are 15 cm and if the refractive index of the material of the lens is 1.5, then focal length of lens in air is ......... cm.

The radii of curvature of the two surfaces of a lens are 20cm and 30 cm and the refractive index of the material of the lens is 1.5 . If the lens is concave - convex, then the focal length of lens is

The radii of curvature of the two surface of a lens are 20 cm and 30 cm and the refractive index of the material of the lens is 1.5 . If the lens is concave - convex, then the focal length of the lens is :

A plano convex lens has radius of curvature 10 cm. Its focal length is 80 cm under water. Calculate the refractive index of the material of the lens, given refractive index of water is 4//3 .

The radii of curvature of the two surfaces of a lens are 20 cm and 30 cm and the refractive index of the material of the lens is 1.5. If the lens is concave -convex, then the focal length of the lens is