You may have noticed that the force is strongest if you use the end of the magnet. A bar magnet's magnetism is strongest at the ends. The ends of the magnet are called its magnetic poles.
The poles are called the north pole (N) and the south pole (S). Why is this?
If you hang up a bar magnet so that it is free to turn around, it will turn until one end points towards the north - this end is the north pole of the magnet. The south pole points towards the south.
north

Two magnets

The diagram shows what happens when the poles of two magnets are close together. They may attract each other, or they may repel each other (push each other away). The arrows show the direction of the force on cach magnet.

A bar magnet turns until it points north-south

1) In each of the diagrams are the magnets attracting each other or repelling each other?

2) a: Copy and complete the sentence:
When a north pole is close to a south pole, the magnets ....
b: Write a similar sentence to say what happens when two north poles are close to each other.

Two magnets can attract or repel each other

Magnet rules

Here are the rules which tell us whether two magnetic poles will attract or repel:
• Like poles repel.
• Unlike poles attract.
In these rules, 'like poles' means both poles are the same (both north poles or both south poles). 'Unlike poles' means one north pole and one south pole. Sometimes people simply remember the phrase 'opposites attract'.

1) Use two bar magnets and test the rules given on the opposite page. Are they correct?

2) Wrap one magnet in paper so that you cannot tell which pole is which Exchange your wrapped magnet with another group. Test the wrapped magnet and label its poles. Unwrap it and see if you are correct.

Making a magnet

You can use a permanent magnet to magnetise a piece of iron or steel. Here is how:
• Lay the piece of iron or steel on the bench.
• Using one pole of the magnet, stroke it gently from one end to the other.
• Stroke it several times, using the same pole, Make sure you always stroke it in the same direction.

stroking the iron piece of iron This end will become the south pole.

3) Copy the diagram which shows how to magnetise a piece of iron. Label the poles of the iron when it has been magnetised.

SE: 1) Use a bar magnet to magnetise a piece of iron or steel.

2) Devise a way to show that the metal has been magnetised.

3) Test the new magnet: which end is its north pole?

4) Can you devise a way to produce a magnet with north poles at both ends?

Summary

• The north pole of a magnet will turn to point north.
• Like poles repel, unlike poles attract.
• A piece of unmagnetised iron or steel can be magnetised by stroking with one pole of a permanent magnet.