A thin plano-convex lens acts like a concave mirror of focal length 0.2 ~m when silvered from its plane surface. The refractive index of the material of the lens is 1.5 . The radius of curvature of the convex surface of the lens will be

Step-by-step solution

Resultant focal length (f) of the given combination is 0.2 ~m . Refractive index of the material, =1.5 From the lens Maker formula, we get 1 f =( -1) ( 1 R₁ - 1 R₂ ) where, R₁ is the radius of curvature of convex surface and R₂ is the radius of curvature of plane surface (R₂= ) . Hence, array ll & 1 f =(15-1) ( 1 R₁ - 1 ) & 1 0.2 =(0.5) ( 1 R₁ ) & R₁=0.5 0.2=0.1 ~m array