[" 4.A concave lens is placed in water.Will there be any change in focal length? "],[" Give reason."]

A convex lens is placed in water. a. Will there be any change in its focal length? B. Give reason.

A concave miror is placed in water will there be any change in focal length? Give reason?

Is there any limit to change of focal length of eye lens ?

If the lens is placed in water instead of air, how does its focal length change?

A concave lens is placed in contact with a convex lens of focal length 25 cm . The combination produces a real image at a distance of 80 cm , when an object is at a distance of 40 cm . What is the focal length of concave lens ?