The poles of a magnet are the places where the magnetic forces are…

The idea

Every magnet has two poles, north and south, and these are the regions where the magnetic force is strongest. You can show this by sprinkling iron filings around a bar magnet: they cluster densely at the ends and are sparse in the middle. When two magnets are brought close together, each exerts a force on the other. Like poles (N–N or S–S) repel, so the magnets push apart; unlike poles (N–S) attract, so they pull together. These forces act without the magnets touching, so attraction and repulsion between magnetic poles are non-contact forces. The pattern of attraction and repulsion is the basis of simple tests for identifying an unknown pole and of understanding how a compass needle responds to a nearby magnet.

What earns the marks

• State that the poles are the ends of a magnet where the magnetic force is strongest, and that a magnet has a north pole and a south pole.
• Describe the interaction between two magnets: like poles repel and unlike poles attract, naming the pole pairs correctly.
• Classify attraction and repulsion between magnetic poles as non-contact forces because the magnets exert forces on each other without touching.
• Use a described test, such as bringing a known pole near an unknown pole, to identify whether the unknown pole is north or south from whether repulsion or attraction occurs.
• Explain that repulsion is the reliable test for a like pole, because attraction can also occur between a magnet and an induced magnet.

Common mistakes and how to put them right

• Saying that like poles attract and unlike poles repel.

  Put it right: Like poles repel and unlike poles attract; remember 'like repels, unlike attracts'.

• Describing magnetic attraction as a contact force because the magnets feel as if they pull together.

  Put it right: The force acts at a distance, so it is a non-contact force.

• Claiming that a magnet has only one pole or that the poles are in the middle.

  Put it right: Every magnet has two poles, located at the ends, where the force is strongest.

Exam tips

• When asked to identify an unknown pole, state that repulsion is the decisive observation, because attraction can happen with an induced magnet as well as with an unlike pole.
• Use the terms 'attract' and 'repel' precisely, and always name the poles involved, for example 'the north pole of one magnet repels the north pole of the other'.
• Link the idea of strongest force at the poles to a practical observation, such as iron filings clustering at the ends of a bar magnet, to gain credit for explaining evidence.