A beam of light is incident through the holes on side A and emerges out of the holes on the other face of the box as shown in the Figure 10.4. Which of the following could be inside the box?

Fig 10.4.jpg

(a) Concave lens

(b) Rectangular glass slab

(c) Prism

(d) Convex lens



Let us go through the options. 

(a) A concave lens : The incident beams of light are parallel. A concave lens would make parallel rays diverge .   The given figure is consistent with the behaviour of light passing through a Concave lens. 



(b) A rectangular glass slab

  • The emergent beams that come out from C and D are laterally shifted and parallel to the incident rays. which is not the case here

(c) A prism : A prism splits white light into 7 colours which emerge at an angle after diverging from their original paths. That is not the case here .


(d) 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 also not the case here

So, the correct answer is (a)

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CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo