NCERT Solutions Curiosity Chapter 2 A water-filled flask behaving like a lens — Activity 2.1: Let us observe
Book page 9 Updated on2026-09-05
Q1.
Do you notice something interesting?
Answer
Yes — the letters of the book look larger when you see them through the water-filled flask.
Why it happens: look at the shape of the water inside the round-bottom flask. It is thick in the middle and thin near the edges — exactly the shape of the curved piece of glass that people long ago called a lens, because it looked like a lentil seed. Light coming from a letter is bent as it passes through this curved body of water, and reaches your eye as though it had come from a much bigger letter. So the flask of water behaves like a magnifying glass.
Check it yourself: move the flask slowly up and down above the page. The letters grow and shrink, and at one position they turn blurred. A lens only magnifies clearly at the right distance — the same reason a microscope has a focusing knob.
Q2.
Now, use a real magnifying glass to look at small organisms, like an ant. Were you able to see the details of its body more clearly?
Answer
Yes. Details that the naked eye cannot separate become clear under a magnifying glass.
On an ant you can now make out:
the body divided into distinct parts, with a narrow ‘waist’ between them;
a pair of bent antennae that the ant keeps tapping the ground with;
six jointed legs, each with tiny claws at the tip;
fine hairs on the body, and the jaws in front.
Why the magnifying glass helps: two points on the ant's leg that are too close together look like one point to the naked eye. The lens makes the ant occupy a much larger part of your field of view, so those two points now fall far enough apart for the eye to see them separately. That is all magnification does — and it is why each better lens, from the magnifying glass to the microscope, showed people more than the one before it.
Q3.
For a long time, people were curious to explore the tiny organisms around them, but they could not see them with their naked eyes. So, how did we finally discover this invisible world? Do you know which scientific discovery helped us see the tiny world for the first time?
Answer
The invention of the microscope. It was the microscope that first opened the hidden world of tiny living creatures.
Scientist
When
What was done
Robert Hooke
1665
Published Micrographia with detailed drawings of tiny things nobody had seen before. His microscope made things look 200 to 300 times bigger than the unaided eye could see. Looking at a thin slice of cork he found many small empty compartments that reminded him of a honeycomb, and called each one a cell — the first use of the word in science.
Antonie van Leeuwenhoek
1660s
A Dutch scientist who made better lenses and built more useful microscopes. He was the first person to clearly see and describe tiny living things such as bacteria and blood cells, and is known as the Father of Microbiology.
Why it took so long: the difficulty was never a lack of curiosity — it was that no tool existed to make these organisms big enough to see. Once lenses were improved enough to be combined into a microscope, the whole world of microbes became visible in a single generation.