Fun with Magnets

Why this chapter matters for UPSC: Magnetism runs from Class VI's compass to the electric motor, the MRI scanner and the evidence for plate tectonics. Prelims asks the basics (which materials are magnetic, where the poles are, why a magnet points north-south) and the applications (electromagnets, MRI, field rules). This chapter is the base. In NCERT's rationalised 2023-24 edition it is Chapter 10, "Fun with Magnets", with the text unchanged.

🧠 First Principles — Read This First

Paheli and Boojho watch a crane in a junkyard: a block lowered onto a heap of scrap lifts away with pieces of iron stuck to it. There must be a magnet at the end of the crane. Magnets also hide in refrigerator stickers, pin holders and pencil boxes whose lids snap shut.

The chapter's ideas, in order:

1. Magnets attract some materials (iron, nickel, cobalt: magnetic) and not others (plastic, wood, leather, paper: non-magnetic).
2. Attraction is strongest near the two ends, the poles.
3. A freely suspended magnet always comes to rest pointing north-south: the basis of the compass.
4. Like poles repel; unlike poles attract.
5. Magnets can be made from iron, and they lose their magnetism if heated, hammered or dropped.

PART 1 — Quick Reference

Natural and Artificial Magnets (NCERT)

Properties of Magnets (NCERT)

PART 2 — Concepts & Narrative

Testing Materials and Soil

NCERT's "Magnes walk": tape a magnet to a hockey stick or walking stick and see what it picks up around the school. Objects that stick contain magnetic materials. Boojho's puzzle: a tailor drops his needle on the floor; a magnet finds it.

Is there iron in your soil? Rub a magnet in sand or soil and shake off the loose grains. Particles that still cling are iron filings, and the amount varies from place to place: many, a few or none.

Poles and Directions

Spread iron filings on paper and lay a bar magnet on them: far more filings cling near the ends than in the middle. The poles are near these ends.

NCERT recalls the legend of the Chinese emperor Hoang Ti, whose chariot carried a statue with an outstretched arm that always pointed south. Suspend a bar magnet by a thread from a stand, away from air currents: however you turn it, it settles in the same north-south line. An iron bar or a wooden scale does not. Using the rising sun (face east and north is on your left) you can tell which end points north.

Travellers once found directions by hanging natural magnets on a thread. The compass is a small box with a glass cover and a magnetised needle pivoted to rotate freely over a dial; the north end of the needle is usually painted a different colour. Turn the box until N and S on the dial line up with the needle's ends.

Attraction and Repulsion

Fix bar magnets on two toy cars. With opposite poles facing, the cars move towards each other; with like poles facing, they move apart. The same can be seen by bringing the poles of one magnet towards a suspended magnet. Two similar poles repel; opposite poles attract. Repulsion, not attraction, is the sure test that a bar is a magnet: an iron bar is attracted by both poles of a magnet, but only a magnet can be repelled by one of them. Boojho asks what happens when a magnet is brought near a compass: the needle swings, because the compass needle is itself a magnet.

NCERT's Puzzles, Solved

NCERT's exercises test the chapter's ideas in everyday settings:

• A plastic pencil sharpener is attracted by both poles of a magnet. Some part of it, most likely the blade, must be made of a magnetic material such as iron. Attraction by both poles shows it is magnetic material, not a magnet.
• "A compass can find the east-west direction at any place." It can, but only indirectly: the needle shows north-south, and east and west follow from it.
• Iron and steel from a junkyard can be sorted from aluminium, copper and plastic with a magnet, which is exactly what the crane in the chapter's opening does.

Magnetic Field Lines (NCERT Class X)

The space around a magnet where its force can be felt is its magnetic field, mapped with iron filings or a compass. NCERT Class X's rules:

• Outside the magnet, field lines emerge from the north pole and merge at the south pole; inside, they run from south to north, so field lines are closed curves.
• Where field lines are closer together, the field is stronger: near the poles.
• No two field lines cross, since a compass at the crossing would have to point two ways at once.

Electricity and Magnetism (NCERT Classes VII and X)

PART 3 — UPSC Integration

The chapter's simple tests (does it stick, where do filings gather, which way does it point, do the poles push or pull) build the vocabulary for a much bigger story. The north-seeking needle became the compass that guided navigation for centuries; Oersted's deflected needle joined magnetism to electricity, giving electromagnets, bells, motors and generators; and magnetism inside the body and in ancient rock gave medicine the MRI scanner and geology the proof of moving continents. Prelims questions test definitions, rules and exceptions; answers should name the property or rule and give one everyday or Indian example.

Exam Strategy

Prelims traps:

• Magnetic materials: iron, nickel, cobalt (NCERT). Plastic, wood, rubber, paper are non-magnetic.
• Magnetite is the natural magnet; artificial magnets come in bar, horse-shoe and cylindrical or ball-ended shapes.
• Every magnet has two poles; cutting a magnet gives two smaller magnets, each with two poles. A cylindrical magnet does not have only one pole.
• Strongest attraction near the poles, weakest in the middle.
• Freely suspended magnet = north-south; a compass shows N-S directly and other directions only from that.
• Repulsion is the sure test of a magnet.
• Heating, hammering, dropping weaken magnets; store in pairs with unlike poles together and soft-iron keepers.
• Field lines: N to S outside, S to N inside, closed, never cross, crowded at poles.
• Oersted 1820; right-hand thumb rule (field round a wire); Fleming's left-hand rule (force, motor).
• Electromagnet = soft iron in a current-carrying coil; temporary.

Mains angle: Explain how the discovery that electric currents produce magnetic fields led to everyday devices such as electromagnets, bells and motors.

Practice Questions

Practice (UPSC-pattern, not past papers).

Prelims:

1. Which of the following is a magnetic material?
   (a) Aluminium
   (b) Copper
   (c) Nickel
   (d) Plastic

2. Iron filings sprinkled on a bar magnet collect mostly:
   (a) In the middle
   (b) Near the two ends
   (c) Evenly all over
   (d) Only at the north pole

3. You have two identical-looking bars, one a magnet and one plain iron. The surest way to identify the magnet is to check whether:
   (a) It attracts iron filings at its ends
   (b) It repels one pole of another magnet
   (c) It is attracted by a magnet
   (d) It is heavier

4. Consider the following statements about magnetic field lines:
   

   1. Outside a magnet they go from the north pole to the south pole.
      
   2. They are closer together where the field is stronger.
      
   3. Two field lines can cross each other.
      Which of the statements given above are correct?
      (a) 1 and 2 only
      (b) 2 and 3 only
      (c) 1 and 3 only
      (d) 1, 2 and 3

5. Bar magnets are best stored:
   (a) With like poles on the same side
   (b) In pairs with unlike poles on the same side and soft-iron pieces across the ends
   (c) Near a television to keep them strong
   (d) In a heated box

6. The scientist who first showed that an electric current deflects a compass needle was:
   (a) Faraday
   (b) Oersted
   (c) Fleming
   (d) Maxwell

7. Strips of normal and reverse magnetic polarity running parallel to the mid-oceanic ridges are evidence for:
   (a) Glaciation
   (b) Sea-floor spreading
   (c) Ocean currents
   (d) Tides

Mains (UPSC-pattern):

1. "A compass needle is a magnet that has found its direction." Explain with reference to the properties of magnets and the use of the compass. (150 words)
2. Describe how electromagnets work and give their uses in industry, medicine and daily life. (150 words)

📦 Revision Capsule

Sources

Sources

• NCERT, Science (Class VI), ch. 13 "Fun with Magnets" (2020-21 print) and ch. 10 in the Rationalised 2023-24 edition: NCERT's book archives as captured by the Wayback Machine, 2020 copy and 2023-24 copy.
• NCERT, Science (Class VII), ch. 10 "Electric Current and its Effects" (Reprint 2024-25); Science (Class X), ch. 12 "Magnetic Effects of Electric Current" (Reprint 2025-26).
• NCERT, Fundamentals of Physical Geography (Class XI), ch. 4 "Distribution of Oceans and Continents", Reprint 2025-26.