A biconvex thin lens is prepared from glass of refractive index 3//2. The two building surfaces have equal radii of 25 cm each. One of the surface is silvered from outside to make it reflecting . Where should an object be placed before this lens so that the image coincides with the object.

A biconvex thin lens is prepared from glass of refractive index 3//2.

1.	A biconvex thin lens is prepared from glass of refractive index 3//2. The two building surfaces have equal radii of 25 cm each. One of the surface is silvered from outside to make it reflecting . Where should an object be placed before this lens so that the image coincides with the object.
Answer» Solution :Here `R_1=+25 cm R_2=-25cm and mu=3//2` IMAGE coincides with OBJECT hence `u=v=-x` (say) `1/F=4/25`, by using `1/v+1/u=1/F, -1/x-1/x=4/25` x=12.5 cm Hence, the object should be PLACED at a distance 12.5 cm in front of the silvered lens.