Question

A plano-convex lens $(\mu =1.5)$ of focal length $20cm$ has its plane side silvered :

• A. The radius of curvature of its curved surface is half that of a surface of equi-convex lens of focal length $20cm$ made of same material .
• B. An object placed at $15cm$ on the axis on the convex side gives rise to an image at a distance of $30cm$ from it .
• C. An object placed at a distance of $20cm$ on the axis on the convex side gives rise to an image at $40cm$ from it .
• D. It acts as a convex mirror .

Answer 1

Answer: (A), (B)

The correct options are
A An object placed at $15cm$ on the axis on the convex side gives rise to an image at a distance of $30cm$ from it .
B The radius of curvature of its curved surface is half that of a surface of equi-convex lens of focal length $20cm$ made of same material .