Question

A concave lens of refractive index 1.5 is immersed in a medium of refractive index 1.65. What is the nature of the lens?

Answer 1

A concave lens made up of certain material behaves as a diverging lens when it is placed in a medium of refractive index less than the refractive index of the material of the lens, and behaves as a converging lens when it is placed in a medium of refractive index greater than the refractive index of the material of the lens, then it behaves as a diverging lens.

In the given case, concave lens is immersed in the medium having refractive index greater then the refractive index of the material of the lens. Therefore, it will behave as a diverging lens.