A plano-convex 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

A plano-convex lens when silvered in the plane side behaves like a concave mirror of focal length 30 cm. However, when silvered on the convex side it behaves like concave mirror of focal length 10 cm. Then the refractive index of its material will be:

A plano-convex lens, when silvered at its plane surface is equivalent to a concave mirror of focal length 28 cm . When its curved surface is silvered and the plane surface not silvered, it is equivalent to a concave mirror of focal length 10 cm then the refractive index of the mateiral of the lens is:

The rear face of an equiconvex lens of focal length 30 cm is silvered that if behave like a concave mirror The focal length of mirror is [ mu_(Lens) = 3/2]

The rear face of an equiconvex lens of focal length 30 cm is silvered that if behave like a concave mirror The focal length of mirror is [ mu_(Lens) = 3/2]

A planoconvex lens behaves like a concave mirror of 30 cm focal length on silvering the plane surface of the lens, but on polishing by silver on convex surface, it acts as is concave mirror of 10 cm focal length. What will be the refractive index of the material of the lens ?