Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
What is a Magnet?
A magnet is an object that attracts certain materials — mainly iron, nickel, and cobalt — and has two poles where the force is strongest.
Natural magnet: Magnetite (lodestone) — found in nature. Artificial magnet: Made by humans — bar magnet, horseshoe magnet, cylindrical magnet.
Magnetic and Non-Magnetic Materials
| Magnetic (attracted to magnet) | Non-Magnetic (not attracted) |
|---|---|
| Iron | Aluminium |
| Steel | Copper |
| Nickel | Wood |
| Cobalt | Plastic |
| — | Glass |
| — | Rubber |
Note: Not all metals are magnetic. Aluminium, copper, gold, silver are metals but are NOT magnetic.
Properties of Magnets
1. Attraction
- Magnets attract objects made of iron, nickel, and cobalt.
- Force is strongest at the poles.
2. Directive Property
- A freely suspended magnet always comes to rest pointing North–South.
- The end pointing North = North Pole (N).
- The end pointing South = South Pole (S).
- This is the basis of the compass.
3. Law of Magnetic Poles (Poles Attract/Repel)
- Like poles repel: N–N push away; S–S push away.
- Unlike poles attract: N–S pull together.
4. Magnets Always Have Two Poles
- You cannot isolate a single pole.
- If you break a magnet in half, each half has its own North and South poles.
Parts of a Bar Magnet
- North Pole — one end, marked N.
- South Pole — other end, marked S.
- Neutral region — middle area where magnetic force is weakest.
Compass
- A compass contains a small, lightweight magnet (needle) balanced on a pivot.
- The needle aligns itself with Earth's magnetic field.
- North end of needle → Geographic North direction.
- Used for navigation — finding directions.
Making a Magnet
Single-Touch Method
1. Place an iron strip on a table. 2. Take a bar magnet and place one pole (say N) at one end of the strip. 3. Slide the magnet along the strip to the other end in one direction only. 4. Lift the magnet and bring it back to the starting end. 5. Repeat 30–40 times. 6. The iron strip becomes a magnet.
Important: Always stroke in one direction. Going back and forth cancels the effect.
Demagnetisation — How Magnets Lose Their Properties
A magnet loses its magnetism when:
- Hammered or dropped repeatedly.
- Heated strongly.
- Rough handling — dropping or banging.
Storing Magnets
- Bar magnets → kept in pairs with unlike poles adjacent, with soft iron pieces (keepers) across the ends.
- Horseshoe magnet → store with a keeper (iron bar across the poles).
- Should be kept away from electronic devices (phones, computers) — their magnetic field can cause damage.
Earth is a Giant Magnet
- Earth behaves like a giant bar magnet.
- Earth's geographic North Pole is near Earth's magnetic South Pole (that's why the North Pole of a compass needle is attracted to it).
- This is why a freely hanging magnet points North–South.
Key Vocabulary
| Term | Meaning |
|---|---|
| Magnet | Object that attracts iron/nickel/cobalt |
| Poles | Ends of magnet where force is strongest |
| Magnetic material | Attracted to a magnet |
| Non-magnetic | Not attracted to a magnet |
| Compass | Navigation device using a magnetic needle |
| Magnetite | Natural magnet (lodestone) |
| Keeper | Iron bar used to preserve magnetism in stored magnets |
Exam Tips
- Like poles repel, unlike attract — this exact phrase is tested.
- Not all metals are magnetic — copper, aluminium are non-magnetic metals — common tricky MCQ.
- A broken magnet has two poles — both pieces become complete magnets.
- Compass needle points North because Earth acts as a magnet.
- Heating or hammering destroys magnetism — heating is most effective.