[" A plano-convex lens "(f=20cm)" is silvered at plane surface.Now it's focal length will b "],[[" (a) "20cm," (b) "40cm],[" (c) "30cm," (d) "10cm]]

A plano-convex lens (f = 20 cm) is silvered at plane surface. Now focal length will be

A plano-convex lens (mu = 1.5) has a curved surface of radiys 15 cm. what is its focal length ?

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

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

As shown in figure, a plano-convex lens of focal length 20 cm is silvered at its plane surface and it is made reflecting, then find new focal length of system.