A plano covex lens when silvered on the plane side behaves

Last updated: 6/9/2023

A plano covex lens when silvered on the plane side behaves like a concave mirror of focal length 60 cm However when silvered on the convex side it behaves like a concave mirror of focal length 20 cm Then the refractive index of the lens is A 3 0 C 1 0 B 1 5 D 2 0