A convex lens has 10 cm focal length in air.What is its focal length in water? (Refractive index of air-water is 1.33, refractive index for air glass = `(1.5)`

A convex lens has 20 cm focal length in air.What is its focal length in water? (Refractive index of air-water is 1.33 , refractive index for air¬glass = 1.5).

A convex lens has 12 cm focal length in air. What is its focal length in water? (Refractive index of air-water is (1.33) , refractive index for air-glass = (1.5) .

A converging lens has a focal length of 20 cm in air. It is made of a material of refractive index 1.6. If it is immersed in a liquid of refractive index 1.3, what will be the new focal length? How does the nature of the lens change. If this lens is immersed is a liquid of refractive index 1.8 ?

If refractive index of glass w.r.t. air is 1.55, then what is the refractive index of air w.r.t. glass.

An equiconvex lens has focal length equal to the radius of curvautre.Its refractive index is