What about the thickness of double convex lens ?

What is a double convex lens ?

(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.)

(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.)

What is the focal length of double concave lens kept in air with two spherical surfaces of radii R_1 = -30 cm and R_2=60 cm . Take refractive index of lens as n = 1.5.