A plano convex lens has focal length `f = 20 cm`. If its plane surface is silvered, then new focal length will be

A point object is placed at a distance of 20cm from a thin plano-convex lens of focal length 15cm If the plane surface is silvered.the image will form at

The radius of curvature of curved surface of a thin plano-convex lens is 10 cm and the refractive index is 1.5 . If the plano surface is silvered, then the focal length will be.

The radius of curvature of curved surface of a thin plano-convex lens is 10 cm and the refractive index is 1.5 . If the plano surface is silvered, then the focal length will be.

A plano-convex lens of focal length 30 cm has its plane surface silvered. An object is placed 40 cm from the lens on the convex side. The distance of the image from the lens is

A plano-convex lens is made of a material of refrative index mu=1.5 .The radius of curvature of curved surface of the lens is 20 cm.If its plane surface is silvered,the focal length of the silvered lens will be