NCERT Solutions for Class 8th Science Chapter 10 .2 What Are the Characteristics of Images Formed by Spherical Mirrors? — Activity 10.3: Let us explore
Book page 15510 Updated on2026-09-19
Q1.
Place the two mirrors side by side in an upright position on a table. Keep the object in front of them at a small distance (3–4 cm away) as shown in Fig. 10.5a. What kind of images do you see in each mirror? Are the images of the same size as the object? Are they erect? Do you see lateral inversion in the images? Write down your observations in your notebook.Fig. 10.5, page 155 — the same toy in front of a concave and a convex mirror. Redrawn sketch of the book’s photographs. (a) At a small distance the concave mirror gives a large erect image and the convex mirror a small erect one. (b) Moved far away, the image in the concave mirror has turned inverted, while the one in the convex mirror is erect and smaller still.
Answer
With the toy only 3–4 cm away:
Mirror
Size
Erect or inverted?
Lateral inversion?
Concave
Enlarged — bigger than the toy
Erect
Yes
Convex
Diminished — smaller than the toy
Erect
Yes
So the answer to the middle question is no — neither image is the same size as the object, and that is already a clear difference from a plane mirror. Both images are erect at this small distance, and both show lateral inversion.
Why lateral inversion appears in both: lateral inversion is not caused by curvature at all. It comes from the fact that we are looking at the object from the mirror's side rather than our own — the side of the toy nearest your right hand is reflected to the side of the image nearest your left. That reversal happens in a plane, a concave and a convex mirror alike.
Q2.
Now slowly move the object away from the mirrors (Fig. 10.5b). What changes do you see in the images in both the mirrors? Do the images become smaller or larger? Do they continue to be erect? Again, note down your observations.Fig. 10.5, page 155 — the same toy in front of a concave and a convex mirror. Redrawn sketch of the book’s photographs. (a) At a small distance the concave mirror gives a large erect image and the convex mirror a small erect one. (b) Moved far away, the image in the concave mirror has turned inverted, while the one in the convex mirror is erect and smaller still.
Answer
Concave mirror. The erect image first grows larger. At one particular distance it blurs; past that distance the image reappears inverted, at first enlarged and then getting steadily smaller the farther the toy goes.
Convex mirror. Nothing dramatic happens. The image stays erect throughout and only becomes a little smaller as the toy is moved back.
Why only the concave mirror flips: a concave mirror converges the reflected rays, so beyond a certain object distance they actually cross in front of the mirror. Once light has crossed over, top and bottom are interchanged and the image is inverted. A convex mirror diverges the reflected rays; they never cross, so its image can never become inverted, no matter where the object is placed.
Q3.
Analyse your observations and draw conclusions.
Answer
Conclusion 1. Spherical mirrors do not behave like plane mirrors. A plane mirror always gives an erect image of exactly the same size; in a spherical mirror the size of the image changes as the object distance changes.
Conclusion 2. A concave mirror can give an image that is enlarged, of the same size, or diminished, and erect or inverted — it all depends on how far the object is from the mirror.
Conclusion 3. A convex mirror is far more predictable: its image is always erect and always diminished, whatever the object distance.
Conclusion 4. Lateral inversion is seen in all three types of mirror, so it cannot be used to tell them apart.
Tip: when you write conclusions in your notebook, state the condition along with the result — 'enlarged and erect when the object is close' is a conclusion; 'enlarged' on its own is not.