NCERT Solutions Curiosity Chapter 10 .3 What Are the Laws of Reflection? — Activity 10.6: Let us explore
Book page 16010 Updated on2026-09-05
Q1.
Let the multiple parallel beams of light fall upon the plane mirror, concave mirror, and convex mirror, one by one. Observe the reflected beams. Is your observation similar to what is shown in Fig. 10.11 (b), (c), and (d)?
Answer
Yes, the observations match the figure exactly:
Plane mirror (Fig. 10.11b) — the reflected beams are still parallel to one another.
Concave mirror (Fig. 10.11c) — the reflected beams come closer together, that is, they converge, and meet at a point.
Convex mirror (Fig. 10.11d) — the reflected beams spread apart, that is, they diverge.
Every single ray still obeys i = r. Because the surface is curved, the normal points in a different direction at each point of the mirror — and that is what makes the reflected beam close in (concave) or spread out (convex). The point F, where a parallel beam is brought together — or from which it seems to spread — is called the focus of the mirror.
Why the three results differ: every one of these beams obeys i = r. On the plane mirror all the normals are parallel, so every beam is turned through the same angle and the set stays parallel. On the concave mirror the normals lean inwards as you go away from the centre, so the outer beams are turned inwards more than the inner ones and the whole set closes in. On the convex mirror the normals lean outwards, so the outer beams are thrown further out and the set opens up.
Tip: keep the comb, torch and mirror all standing on the same sheet of paper. If the torch is lifted even slightly the beams leave the plane of the paper and the pattern becomes hard to see.