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 Figure10.3. 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
Let us go through the options.
(a) A rectangular glass slab :
- The emergent beams that come out from C and D are laterally shifted
- Emergent rays have undergone lateral displacement
- Emergent rays have come out parallel to the incident rays.
This is consistent with the behaviour of light passing through a glass slab
(b) A convex lens : The incident rays passing through the holes A and B are parallel. A convex lens makes parallel rays converge onto a single point (the focus), which is not the case here .
(c) A concave lens : A concave lens would make parallel rays diverge , which is also not the case here .
(d) A prism : A prism splits white light into 7 colours which emerge at an angle after diverging from their original paths. That is also not the case here .
So, the correct
answer is (a)
