Question

Explain how will the power of a lens change when its surrounding medium is changed

from air to water. Give the condition under which a convex lens will start working as a

diverging lens by changing its surrounding medium. Show this phenomenon by drawing a

ray diagram

Answer 1

Explanation:

As the medium is changed from air to water the refractive index of medium increases. As a result, the focal length will increase since the rays will take a lot of distance to converge.

Since, the focal length is inverse of the power, hence the power will decrease. If the glass lens is taken to a surrounding medium whose refractive index is more than that of a glass the converging lens will behave like a divergent lens.