Question

Two similar convex lenses are made up of two different materials, as shown in the figures below. Find the number of images formed in the following setups:

(i)
(ii)

Answer 1

1. The convex lens is made of two different materials, so each half has a different refractive index and hence a different focal length. Parallel rays therefore focus at two different points, forming two images.
2. The two convex lenses of different materials act together as a single coaxial lens system with one effective focal length. Hence, only one image is formed.