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

The idea

Every magnet has two poles, north seeking and south seeking, and they are where the magnetic force is strongest. On a field diagram the poles are easy to spot because the field lines are packed closest together there, and in a practical the iron filings pile up thickest at the two ends of a bar magnet. Move away from a pole and the lines spread out, so the field and the force both get weaker with distance. The two ideas are examined together: the field is strongest at the poles and weakens further from the magnet. You cannot get a single pole on its own, because snapping a bar magnet in half simply gives two shorter magnets, each with a north and a south.

What earns the marks

• Stating that the magnetic field is strongest at the poles.
• Stating that the magnetic field gets weaker further from the magnet.
• Identifying the poles on a field diagram as where the field lines are closest together.
• Stating that cutting a bar magnet in half gives two magnets, each with a north and a south pole.

Common mistakes and how to put them right

• Ticking 'the magnetic field is uniform away from the poles', which is false for a bar magnet.

• Drawing field lines that cross or converge to a single point.

• Believing a single isolated north pole can be produced by cutting a magnet.

• Assuming the force is strongest at the middle of the bar because that is the bulk of the magnet.

Exam tips

• Read the spacing of field lines as the strength of the field: closest lines mean strongest field.
• Tick-two questions need both correct statements; one right and one wrong scores one.
• Answer the where and the how: strongest at the poles, weaker with distance.