Question

Beams of light are incident through the holes A and B and emerge out of box through the holes C and D respectively as shown in the figure. Which of the following could be inside the box?

• A. A rectangular glass slab
• B. A convex lens
• C. A concave lens
• D. A prism

Answer 1

The correct option is A

A rectangular glass slab

If 'i' is the angle of incidence and x is the refracted angle then at the second surface also x will be the angle of incidence by alternate angle property and hence, angle 'i' will be the emergent angle which is equal to the incidence angle. So these two rays will be parallel. Hence, angle between incident ray and emergent ray = $0^{\circ }$. So it is a rectangular glass slab.