GCSE Physics · AQA 8463 · Topic 4.7.1
Permanent and induced magnetism, magnetic forces and fields
Key points
- Magnets have a north pole and a south pole. Like poles repel; unlike poles attract. The magnetic force is non-contact.
- A permanent magnet produces its own field. An induced magnet becomes a magnet only when placed in a magnetic field, and the force between them is always attraction.
- Field lines go from north to south. The field is strongest at the poles, where lines are closest.
- A compass contains a small bar magnet that points along the field. Compasses show that Earth has a magnetic field, which suggests its core is magnetic.
- A current in a wire makes a circular magnetic field around it. Coiling the wire into a solenoid concentrates the field; adding an iron core makes a strong electromagnet that can be switched on and off.
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Magnets attract paper clips, stick to fridges and point compass needles north. This sub-topic explains what magnetic poles and fields are, which materials are magnetic, and how we know the Earth itself behaves like a magnet.
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