Question

A bicanvex thin lens is prepared from glass of refractive index 3/2. The two bounding 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 1

Image coincides with object, hence, u = v = -x (say)

Substituting in equation (iv), we have

Hence, the object should be placed at a distance 12.5 cm in front of the silvered lens.