NCERT Solutions Curiosity Chapter 2 How small a thing can the eye actually see? — In-text Questions
Book page 9 Updated on2026-09-05
Q1.
Have you ever noticed the smallest organism around you that is visible to the naked eye? Think about it — how small a thing can your eyes actually see?
Answer
The smallest living things most of us can spot unaided are creatures like a small ant, a mite on a leaf, or a tiny insect on a flower — roughly the size of a full stop or a mustard seed. Below about that size the eye can no longer separate an object from its background.
Why there is a limit: the human eye can only see objects that are above a certain size. An object smaller than that forms too small an image for the eye to register as a separate shape, so it simply disappears from view. This is not a failure of attention — it is a fixed limit of the eye, and it is exactly why so many living things around us stayed unknown for so long.
Try This: put a full stop on paper with a sharp pencil and step back slowly. The distance at which the dot vanishes tells you the limit of your own eye. Now look at the same dot through a magnifying glass — it becomes a rough, uneven blob. Every organism in this chapter is smaller than that dot.
Q2.
You might have seen some people using reading glasses. How does it help them see better? Or what happens when we use a magnifying glass to observe something?
Answer
Both work in the same way — a curved piece of glass makes the object appear larger to the eye than it really is.
Reading glasses use a lens that is thick in the middle and thin at the edge. Print that looked small and blurred is made to appear bigger and sharper, so the reader can make out the letters comfortably.
A magnifying glass does the same for an object you hold under it. The ant, the grain of sand or the flower part fills a much larger part of your field of view, so details that were merged together become separate.
Why it happens: the piece of glass is curved — thick in the middle, thin at the edge, like a lentil seed, which is why it is called a lens. Light from the object is bent as it passes through the lens and enters the eye as if it had come from a much larger object. Improving lenses in exactly this way, step by step, is what finally produced the microscope.