question_answer

The layered lens shown in Fig. is made of two different transparent materials. A point object is placed on its axis. How many images does it form?

Answer:

               The lens is made up of two materials of different refractive indices. It has two different focal lengths given by \[\frac{1}{{{f}_{1}}}=({{\mu }_{1}}-1)\left[ \frac{1}{{{R}_{1}}}-\frac{1}{{{R}_{2}}} \right]\] and        \[\frac{1}{{{f}_{2}}}=({{\mu }_{2}}-1)\left[ \frac{1}{{{R}_{1}}}-\frac{1}{{{R}_{2}}} \right].\] So the given lens will form two different images of the point object.