If a substance is behaving as convex lens in air and concave
lens in water then which one of the following is its refractive
index?

When does a convex lens behave as a concave lens ?

When does a convex lens behave as a concave lens ?

A lens behaves as a converging lens in air and a diverging lens in water. The refractive index of the material is (refractive index of water =1.33 )

A lens behaves as a converging lens in air and a diverging lens in water. The refractive index of the material is (refractive index of water =1.33 )

A lens behaves as a converging lens in air and as a diverging lens in water. If refractive index of water is 1.33 , the refractive index of the material of the lens will be

A lens behaves as a converging lens in air and a diverging lens in water. The refractive index of the material is