The radii of curvatures ( R ) of biconvex lens is same. An object is kept at center of curvature. The refractive index of material is n. Lens is kept in air.
What is focal length ?

The radii of curvatures ( R ) of biconvex lens is same. An object is kept at center of curvature. The refractive index of material is n. Lens is kept in air. Find out image distance.

The radius of curvature of a plano-convex lens is R. The refractive index of material of prism is n then find the focal length of the lens ?

The focal length of an equi-convex lens is greater than the radius of curvature of any of the surfaces. Then, the refractive index of the material of the lens is

(i) If f = 0.5 m for a glass lens, what is the power of the lens? (ii) The radii of curvature of the faces of a double convex lens are 10 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 focal length in water? (Refractive index of air-water = 1.33, refractive index for air-glass = 1.5.)

The two surfaces of a 1 biconvex lens has same radii of curvatures. This lens is made of glass of refractive index 1.5 and has a focal length 10 cm in air. The lens is cut into two equal halves along a plane perpendicular to its principal axis to yield two plano-convex lenses. The two pieces are glued such that combination lens is immersed in water (refractive index = 4/3 ), its focal length (in cm) is

(ii) The radii of curvature of the faces of a double convex lens are 10 cm and 15cm. Its focal length is 12 cm. What is the refractive index of glass ? (Refractive index of air-water = 1.33. Refractive index for ar - glass = 1.5.)