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NCERT Solutions for Class 8th Science Chapter 10 .1 What Are Spherical Mirrors? — Activity 10.1: Let us explore

Book page 15310 Updated on2026-09-19

Q1.
Take a shiny metallic spoon and hold its curved surface close to your face. Can you see your image in it?
Answer

Yes, clearly. A polished steel spoon reflects light in the same regular way a mirror does, so an image of your face is formed in it.

Why it happens: a polished metal surface is smooth on the scale of light, so a parallel beam falling on it stays organised after reflection — every ray obeys the law of reflection and neighbouring rays stay together. That is what forms an image. A dull, scratched spoon scatters the rays in all directions and shows no image, only a bright patch.
Q2.
Notice the image of your face. Is it different from the image you see in a plane mirror?
(a) Inner (hollow) side(b) Outer (bulging) sideimage is invertedimage is erect and smaller
Fig. 10.1, page 153 — your own face seen in a shiny metal spoon. Redrawn sketch of the book’s photograph: the hollow inner side acts as a concave mirror and turns the face upside down, while the bulging outer side acts as a convex mirror and gives an erect but smaller face.
Answer

Yes, very different. In a plane mirror your face is the same size and erect. In the hollow inner side of the spoon, held close, your face looks much larger — and it is still erect.

Why it happens: the inner side of the spoon is a concave surface. Because it curves inwards, the rays leaving your face are turned inwards on reflection. When your face is quite close to the spoon those reflected rays still spread apart on the way to your eye, so your eye traces them back to a point behind the spoon — and the picture your eye builds there is bigger than your face.
Q3.
While observing the image, slowly move the spoon away from your face. Do you observe any change in the image?
(a) Inner (hollow) side(b) Outer (bulging) sideimage is invertedimage is erect and smaller
Fig. 10.1, page 153 — your own face seen in a shiny metal spoon. Redrawn sketch of the book’s photograph: the hollow inner side acts as a concave mirror and turns the face upside down, while the bulging outer side acts as a convex mirror and gives an erect but smaller face.
Answer

Yes, and the change happens in a definite order:

  1. At first the image stays erect and grows larger.
  2. At one particular distance it blurs out and cannot be seen properly.
  3. Beyond that distance the image comes back inverted (upside down) — first large, then getting steadily smaller as the spoon moves farther away.
Why it happens: a concave surface converges the reflected rays. While your face is nearer than a certain distance the converging is not enough to bring the rays to a meeting point before they reach your eye, so the image is erect and enlarged. Past that distance the rays actually cross over in front of the mirror, and an image formed after the rays have crossed is upside down. The flip is not gradual — it is the crossing point moving past your eye.
Q4.
Now flip the spoon and repeat the same steps.
Answer

With the bulging outer side facing you the behaviour is far simpler. The image is always erect and always smaller than your face, at every distance. As you move the spoon away the image shrinks a little more, but it never flips over.

Why it happens: the outer side is a convex surface. It spreads the reflected rays apart instead of pulling them together, so the rays never cross. Rays that never cross can never form an inverted image, which is why a convex surface can only ever give an erect, diminished one.
Try This: a bulging spoon also shows you a strip of the whole room, not just your face. That extra width is exactly why convex mirrors are used as side-view mirrors.
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