NCERT Solutions Curiosity Chapter 10 .1 What Are Spherical Mirrors? — Activity 10.2: Let us distinguish
Book page 15510 Updated on2026-09-05
Q1.
Now view them from the side, keeping your eye at their level, to identify whether the reflecting surface is curved inwards or outwards (Fig. 10.4).
Answer
Looking along the surface, edge-on, the shape shows up at once:
If the shiny surface dips down in the middle — the edges stand higher than the centre — it is a concave mirror.
If the shiny surface rises in the middle — the centre stands higher than the edges — it is a convex mirror.
Seen edge-on, the difference is obvious: the shiny side of a concave mirror is hollowed inwards; the shiny side of a convex mirror bulges outwards. The shaded part is the non-reflecting back.
Why the eye must be at surface level: from directly above, both mirrors look like flat silver discs, because you are seeing the surface face-on and the small rise or dip is hidden. Bringing the eye down to the level of the mirror lets you see the profile of the surface against the background, and a difference of even a millimetre becomes visible.
Check it yourself: without moving the mirrors you can confirm the answer a second way — put a small object 3–4 cm in front of each. The mirror that enlarges it is concave; the one that shrinks it is convex.