The radius of curvature of the faces of a double convex lens are `10 cm and 15 cm`. If focal length of lens of lens is `12 cm`, find the refractive index of the material of th lens.

The radii of curvature of the surfaces of a double convex lens are 20 cm and 40 cm respectively, and its focal length is 20 cm . What is the refractive index of the material of the lens ?

(i) If f = + 0.5 m , what is the power of the lens ? (ii) The radii of curvature of the faces of a double convex lens are 9 cm and 15 cm . Its focal length is 12 cm . What is the refractive index of glass ? (iii) A convex lens has 20 cm focal length in air. What is the focal length in water ? (Refractive index of air-water = 1.33 , refractive index of air-glass = 1.5 ).

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

If in a plano-convex lens, the radius curvature of the convex surface is 10 cm and the focal length of the lens is 20 cm , then the refractive index of the material of lens will be

The radius of curvature of convex surface of piano convex lens is 10 cm and its focal length is 30 cm, then the refractive index of the material of the lens is

The power of a biconvex lens is 10 dioptre and the radius of curvature of each surface is 10 cm. Then the refractive index of the material of the lens is