Question

 Find focal length and nature of a silvered equviconvex lens of radius of curvature 20 cm & refractive index 2 placed in a medium of refractive index 3. 

(a) +30 cm, silvered lens will be like a concave mirror or converging 

(b) +30 cm, silvered lens will be like a convex mirror or diverging 

(c) +20 cm, silvered lens will be like a concave mirror or converging 

(d) +20 cm, silvered lens will be like a convex mirror or diverging

Answer 1

i.e. silvered lens will be like a concave mirror of focal length 30 cm i.e. nature will be converging.