Question

A beam of parallel light rays is incident through the holes on one side of a box and emerges out through the holes on its opposite side as shown in the diagram below:

Which of the following could be inside the box?

Options

• a rectangular glass block

• a concave lens

• a convex lens

• a glass prism

Answer 1

A concave lens

Explanation:

The diagram shows that parallel light rays enter the box and converge to meet at a single point after emerging. A convex lens is a converging lens that bends parallel incident rays inward toward a common focal point. The other options either cause lateral displacement, divergence, or dispersion rather than focusing parallel rays to a point.