Educational Galaxy

Exploring Magnets — EG's own notes, in simple words

Book: Curiosity (CBSE, Class 6)  |  Chapter 4  |  Medium: English

Diagram (labels are printed on the image): A U-shaped magnet with an iron nail lying nearby and a wooden block below it. The nail is made of a magnetic material; the wooden block is not attracted by a magnet. Note: this picture does not show the nail being attracted — it shows the objects side by side.

A child using a compass outdoors. A general picture about finding direction with a magnet.

Diagram (labels are printed on the image): A bar magnet has a north pole (N) at one end and a south pole (S) at the other. A compass needle is itself a small magnet, so it turns to point north-south.

Diagram (labels are printed on the image): Iron filings stick in large numbers near the two ends (poles) of a bar magnet and only very few stick in the middle — the poles are where attraction is strongest.

What the chapter is about

A magnet is an object that attracts certain materials — iron, nickel and cobalt — without even touching them. The earliest magnets were found in nature: a rock called lodestone, made of the mineral magnetite, was already known in ancient times, and its name comes from Magnesia, the place where it was found. Most magnets we use today are artificial, made by magnetising steel or iron.

Not everything is attracted. Materials attracted by a magnet are called magnetic materials: iron nails, steel needles and paper clips. Materials not attracted are non-magnetic: wood, plastic, rubber, glass, copper and aluminium. Note the trap: a magnet does not attract all metals. Copper, aluminium and brass coins are metals, but they are not magnetic.

Every magnet has two poles — a north pole (N) and a south pole (S). The poles are the ends where attraction is strongest; the middle attracts least. If a magnet is hung freely by a thread, it turns until it points north-south. The end pointing north is its north pole, and the end pointing south is its south pole. That is how poles are named, and it is also why a compass works.

The pole rule is the heart of the chapter: like poles repel each other, and unlike poles attract each other. North pushes north away; north pulls south towards itself. A magnet's force works at a distance and even through non-magnetic things: a magnet can pull an iron nail through a sheet of paper, a plastic sheet or glass, because those materials do not block magnetism.

Two more properties surprise students. First, if a bar magnet is broken into two pieces, each piece becomes a complete magnet with its own north and south poles — a single pole is never found alone. Second, a magnet can be made by rubbing: stroke an iron nail or steel needle again and again in one direction with one pole of a bar magnet, and it becomes a magnet itself. And magnetism can be lost: strong heating, hammering or dropping a magnet again and again weakens it.

Magnets are used everywhere. A compass needle, itself a small magnet, points north-south because the Earth behaves like a giant magnet. Fridge doors close with small magnets; scrapyard cranes lift iron with electromagnets that can be switched on and off; and magnets inside motors, generators, speakers and headphones turn electricity into movement and sound. To store bar magnets safely, keepers (small iron pieces) are placed across the poles, and magnets are kept apart so they do not weaken each other.

What you should learn

• Name magnetic materials (iron, nickel, cobalt, steel) and non-magnetic ones (wood, plastic, copper, aluminium, glass).
• State the pole rule exactly: like poles repel, unlike poles attract.
• Explain how a freely suspended magnet and a compass find north-south.
• Describe how to make a magnet by rubbing, and how magnetism can be lost.
• Explain why a broken magnet still has two poles, and why a magnet works through paper.

Chart / Table: What happens between two poles?

Table: What happens between two poles?

Table: Magnetic or not?

Practice set — try it yourself

1. Name three magnetic materials and three non-magnetic materials.
   Hint: Think about iron versus wood and plastic.
2. What happens when the north pole of one magnet is brought near the north pole of another?
   Hint: Think about the like-pole rule.
3. How does a compass help a traveller?
   Hint: Think about the north-south direction.
4. A coin is not attracted by a magnet. What can you say about the coin's material?
   Hint: Think about which metals magnets attract.
5. How can you keep a magnet strong for a long time?
   Hint: Think about heating, hammering and dropping.

Questions with Answers

1. What is a magnet? Give examples of magnetic and non-magnetic materials.
   A magnet is an object that attracts iron, nickel and cobalt. Iron nails, steel pins and nickel coins are magnetic materials. Wood, plastic, rubber and copper are non-magnetic materials because a magnet does not attract them.
2. State the law of magnetic poles and give an example.
   Like poles repel each other and unlike poles attract each other. For example, if the north pole of one magnet is brought near the north pole of another, they push apart, but a north pole and a south pole pull towards each other.
3. Why does a freely suspended magnet always point north-south?
   The Earth itself acts like a giant magnet. Its magnetic field turns a freely suspended magnet until its north pole points roughly towards the Earth's geographic north, so the magnet rests in the north-south direction.
4. How is a compass useful?
   A compass contains a small magnetised needle that is free to turn. Since it always points north-south, a traveller, sailor or trekker can find directions even in a forest, desert or sea where there are no landmarks.
5. An iron nail is brought near a magnet and sticks to it, but an aluminium strip does not. Explain.
   Iron is a magnetic material, so the magnet attracts the nail. Aluminium is a non-magnetic material, so the magnet has no attraction for it. This shows that magnets attract only certain metals, not all metals.

More NCERT-exercise questions — extra practice

1. What is a lodestone? Why is it called a natural magnet?
   Lodestone is a naturally magnetic rock made of the mineral magnetite, found in nature. It is called a natural magnet because it was not made by people — it occurs in the Earth already magnetised.
2. Fill in the blank: Like poles ________ each other, and unlike poles ________ each other.
   Repel; attract.
3. True or False: A magnet attracts a copper coin because copper is a metal. Give a reason.
   False. A magnet attracts only certain materials — iron, nickel, cobalt and steel. Copper is a metal, but it is non-magnetic.
4. How can you find which end of an unmarked bar magnet is its north pole?
   Hang the magnet freely by a thread and let it settle. The end pointing towards geographic north is the north pole; the other end is the south pole.
5. A magnet is broken into two pieces. Will one piece have only a north pole? Explain.
   No. Each piece becomes a complete magnet with its own north pole and south pole. A single pole never exists alone.
6. Why can a magnet pick up an iron nail that is lying under a sheet of paper?
   Because magnetic force works at a distance and passes through non-magnetic materials. Paper does not block magnetism, so the nail is still attracted.
7. How can you make a magnet from an ordinary steel needle?
   Rub the needle again and again in one direction with the same pole of a bar magnet. After many strokes, test it: if it attracts pins or paper clips, it has become a magnet.
8. Name two ways in which a magnet can lose its magnetism.
   Strong heating, and repeated hammering or dropping. Both disturb the alignment inside the magnet that makes it magnetic.
9. Why does a compass needle point north even though nobody turns it?
   Because the compass needle is itself a small magnet, and the Earth behaves like a giant magnet. The needle turns until it lines up north-south with the Earth's magnetic field.
10. Atharv rolls a bar magnet over a heap of steel U-clips. At the two ends (A and C) about 10 clips stick, but in the middle (B) only about 2 stick. Which option matches: (i) 10, 2, 10 or (ii) 10, 10, 2?
    Option (i) 10, 2, 10. The most clips stick at the poles (the ends), and very few stick in the middle, because attraction is strongest at the poles.
11. Reshma has three identical-looking bars: two are magnets and one is plain iron. With no other material, how can she find which two are magnets?
    By repulsion. Bring the bars near each other in pairs: the two magnets will repel each other when like poles face. Iron is attracted by a magnet but never repels one, so the bar that never repels is the plain iron bar. Attraction alone cannot prove a bar is a magnet — repulsion can.
12. You have an unmarked magnet and another magnet with its poles marked. How do you find the unmarked magnet's poles?
    Bring the marked north pole near one end of the unmarked magnet. If that end is pushed away (repulsion), it is also a north pole; if it is pulled closer (attraction), it is a south pole. Check the other end the same way — it must be the opposite pole.
13. If the Earth itself is a magnet, what are the poles of the Earth's magnet, judging by a compass?
    A compass needle's north-seeking end points towards geographic north, and unlike poles attract. So the Earth's magnetic pole near geographic north must be a magnetic south pole, and the one near geographic south a magnetic north pole. That is why the needle lines up north-south.
14. A mechanic's steel screws keep falling off his screwdriver while he repairs a gadget. Suggest a fix from this chapter.
    Magnetise the screwdriver: stroke its tip again and again in one direction with one pole of a bar magnet, about 30–40 times. The magnetised tip will then hold the steel screws instead of letting them fall.
15. Two ring magnets X and Y are stacked so that X floats above Y and does not slide down. Why? How can X be brought into contact with Y without pushing either magnet?
    X floats because like poles are facing each other and repel — the repulsion balances X's weight. Turn X over (flip it) so that unlike poles face each other: then attraction pulls X down into contact with Y, with no pushing needed.
16. Name the shapes of magnets shown in the chapter.
    Bar magnet, U-shaped magnet, ring magnet, disc magnet, cylindrical magnet and spherical magnet. Whatever the shape, a magnet always has its poles in pairs — never a single pole alone.
17. What is special about the needle of a magnetic compass, and how is the compass box used?
    The needle is itself a small magnet, mounted on a pin so it can turn freely, and its north-seeking end is usually painted red. Put the compass down, wait for the needle to rest north-south, then gently rotate the box until the N and S marks on the dial line up with the needle — now all directions on the dial are correct for that place.
18. State True or False with reasons: (i) A magnet can be broken to get a single pole. (ii) Similar poles repel each other. (iii) Iron filings mostly stick in the middle of a bar magnet. (iv) A freely suspended bar magnet always aligns north-south.
    (i) False — every broken piece is a complete magnet with both poles. (ii) True — like poles repel. (iii) False — filings stick mostly at the poles (ends), very few in the middle. (iv) True — because the Earth behaves like a giant magnet.

How to use this page: Read the summary, say the Key Terms in your own words, then try the practice set without looking. Use the Questions with Answers to check yourself afterwards. Ask your teacher or parent to check your answers.