Probe and Ponder — The Opening Questions — "Light: Mirrors and Lenses"

1. 13 marksCuriosity Grade 8, Chapter 10, page 152

   Can we make mirrors which can give enlarged or diminished images?

   Hint. The chapter answers this with the very first activity you do.

   Yes — and Activity 10.1 shows you how simply.

   Hold a shiny metallic spoon close to your face. Look at its inner curved surface — the image is enlarged (and, held close, erect). Flip it and look at the outer curved surface — the image is smaller and erect.

   ✦ A curved reflecting surface is all it takes. A flat mirror always gives an image the same size as the object; a spoon does not, because the surface is not flat. The chapter builds an entire vocabulary from this one household object: mirrors curved inwards are called concave, and curved outwards are called convex.

   And the enlarging or diminishing is not a fixed property of the mirror alone. A concave mirror gives an enlarged image only when the object is close; move the object away and the image shrinks and eventually flips upside down (Activity 10.3). So the answer is yes, mirrors can do this — and how much, and whether the image is upright or inverted, depends on the shape of the mirror and the distance of the object.

2. 23 marksCuriosity Grade 8, Chapter 10, page 152

   On side-view mirrors of vehicles there is a warning: 'Objects in mirror are closer than they appear'. Why is this warning written there?

   Hint. These mirrors are not flat — the chapter tells you which kind, and what that kind always does to size.

   Because side-view mirrors are convex mirrors, and a convex mirror always makes things look smaller than they really are.

   Look at the side-view mirrors on vehicles. These mirrors are convex. They always form an erect image of the traffic behind and smaller than the actual vehicles.

   Why smaller looks farther. A driver judges distance partly by size — a smaller image is read as a farther object. Since the convex mirror shrinks the image of a car that may in fact be quite close, the driver's instinct can badly underestimate how near it really is. The warning exists precisely to correct for this built-in shrinking.

   ✦ And the shrinking is the whole reason these mirrors are used at all, not a flaw to be tolerated. Since the convex mirror is curved outside, it provides a much wider area of the road behind — the same curve that shrinks the image is what lets the mirror fit a much wider scene into the same small glass. The warning is the price of a genuinely useful trade-off.

3. 33 marksCuriosity Grade 8, Chapter 10, page 152

   Why is there a curved line on some reading glasses?

   Hint. Look at what a curved transparent surface does to the size of letters underneath it, in Activity 10.8.

   Because part of the lens is curved to make nearby print look larger — the same effect a drop of water has on the text beneath it.

   The letters under the water drop look different — they might appear larger than the letters nearby! The curved surface of the water drop made the size of the text look different.

   Bifocal-style reading glasses often carry exactly such a curved region — a small convex zone built into the lower part of the lens — so that looking through that line magnifies close text for reading, while the rest of the lens is shaped for distance. Since a lens is defined by its curvature (a lens which is thicker at the middle as compared to the edges is called a convex lens), a visible line marks where the curvature — and so the magnifying effect — changes.

   ✦ This is the same idea the chapter uses the magnifying glass to illustrate: it is also a lens that helps in reading small print by making the letters appear bigger. A curved line on reading glasses is a magnifying glass built into part of the lens rather than held separately.

4. 43 marksCuriosity Grade 8, Chapter 10, pages 152-153

   Meena saw her face enlarged in one curved mirror and upside down in another, and tiny in a third. Recall what she already knew from Grade 7, and explain her confusion.

   Hint. She was comparing these mirrors to a kind of mirror that never changes size at all.

   Meena's confusion came from expecting all mirrors to behave like the plane mirror she already knew.

   She remembered doing activities with a mirror earlier where the image formed by the mirror was of the same size as the object and was erect (in the chapter 'Light: Shadows and Reflections' in Curiosity, Grade 7).

   A plane mirror always gives an erect image the same size as the object — no exceptions, whatever the distance. So when Meena's face came out enlarged in one science-centre mirror, upside down in a second view, and tiny in a third, none of it fit what she had learned to expect.

   ✦ The guide's answer names exactly what was different: These are not plane mirrors ... These are spherical mirrors. When the mirror is curved inward or outward, your image looks different in them! Since a spherical mirror's surface is curved rather than flat, the size and orientation of the image can change with the shape of the mirror and the position of the object — which a plane mirror's flat surface never allows. Her puzzle is the whole reason this chapter exists.

5. 53 marksCuriosity Grade 8, Chapter 10, page 153

   Meena saw a different image at each of two curved mirrors at the science centre — enlarged and erect at one, and upside down at the other, while her brother standing farther away also looked upside down. What can you already infer about these two mirrors before reading further?

   Hint. One detail matters more than it looks: her brother was standing farther from the mirror than Meena was.

   A reasonable inference, to be confirmed later in the chapter: at least one of the mirrors is concave, and how the image looked depended on how far the person was standing from it.

   Meena, standing close, saw her own face enlarged and (it can be inferred) the right way up. Her brother, standing farther away at the very same mirror, appeared upside down. Since the same mirror gave two different kinds of image for two different distances, the mirror's behaviour must depend on the object's distance from it — which a plane mirror's image never does.

   ✦ This is exactly what Activity 10.3 later measures directly. In the concave mirror, when the object is placed close to the mirror, the image is erect but larger ... when the object is moved farther away, the image becomes inverted. Meena close, and her brother farther back, at the same concave mirror, is precisely this pattern acted out by two people instead of one toy.

   The tiny image she saw in the third mirror is consistent with a convex mirror, which the chapter says always gives a diminished image, whatever the distance — nothing further needs to be inferred about that one; the size alone marks it.

Solutions written by the tuition.in editorial team and checked against NCERT Curiosity — Textbook of Science for Grade 8, Chapter 10 (hecu110.pdf), Reprint 2026-27, pages 152-169. Questions are referenced from the NCERT textbook for identification.