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NCERT Solutions Curiosity Chapter 4 Activity 4.2: Let us investigate — Poles of Magnet

Book page 64 Updated on2026-09-05

Q1.
Do all parts of a magnet attract magnetic materials equally?
Answer

No. The pull of a magnet is not the same everywhere along it. It is strongest at the two ends and weakest in the middle.

You can feel this yourself: touch the middle of a bar magnet to a heap of pins and lift it — hardly any pins come up. Touch an end to the same heap and a whole bunch clings on.

Why it happens: the magnetic strength of a magnet is concentrated at its two ends. These strong ends are called the poles of the magnet. The region near the middle is almost neutral, so a magnetic object placed there feels very little pull.
Q2.
Spread some iron filings on a sheet of paper. Place a bar magnet over them. Tap the paper and observe carefully what happens to the iron filings. Do you observe anything special about the way they stick to the magnet? Do the iron filings stick all over the magnet uniformly? Or do the iron filings stick more at some places?
Answer

Observation: the filings do not spread evenly. They gather in two thick, bushy clumps at the two ends of the bar magnet, and only a few stray filings are seen along the middle.

N S Filings crowd here almost bare and here
Fig. 4.4 redrawn: iron filings pile up at the two ends of a bar magnet and thin out towards the middle.

Answers to the three questions:

  • Yes, something special is seen — the filings arrange themselves in two bunches, one at each end, and they stand out like a beard rather than lying flat.
  • No, they do not stick uniformly all over the magnet.
  • Yes, they stick far more at the two ends. These strong ends are the poles of the magnet — the North pole and the South pole.
Check it yourself: Instead of putting the magnet on the filings, place a thin card over the magnet and sprinkle the filings on top of the card. Tap the card gently. The filings do not just clump — they line up in beautiful curved lanes running from one pole to the other. That pattern is a picture of the magnet's field.
N S
The pattern the filings make on a card above a bar magnet. The curved lanes leave the North pole, loop around and come back into the South pole — and they are packed most tightly at the poles, which is why the pull is strongest there.
Q3.
If we repeat this activity with magnets of other shapes, do we get the same result?
Answer

Yes — the result is the same for every shape. Whatever the shape of the magnet, most of the iron filings collect at its poles.

Shape of magnetWhere the filings crowd
Bar magnetAt the two flat ends
U-shaped (horseshoe) magnetAt the two open tips, which are close together
Ring magnetOn the two flat faces (the top face and the bottom face)
Disc / cylindrical magnetOn the two flat circular faces
Why the shape does not change the rule: shape decides only where the poles sit, not whether they exist. Every magnet, of every shape and size, has exactly two poles, and the filings always mark them out for you. That is why the “More to know!” box at the end of the chapter says that the poles occur in pairs no matter what the magnet looks like.
Tip: A U-shaped magnet lifts more pins than a bar magnet of the same material because both its poles face the same way and pull on the same heap together.
Q4.
Can we find a magnet with a single pole?
Answer

No. A magnet with a single pole cannot exist. North and South poles always occur in pairs.

Test it: take a bar magnet marked N and S, and break it in two.

One magnet: N ——— S
Break it → two magnets: N ——— S   and   N ——— S
Break each again → four magnets, each still with both poles
However small the piece, it always has a North pole and a South pole.
Why it happens: a magnet is not made of a “north lump” joined to a “south lump”. Every tiny part of the material is itself a complete miniature magnet with two ends, all lined up in the same direction. Cut anywhere and you simply expose the two ends of the smaller stack — so a fresh N and a fresh S appear at the cut.
Did you know? Scientists have searched for a lone magnetic pole (a magnetic monopole) for over a hundred years and have never found one. So far, nature has kept the rule with no exceptions.
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