Poles of a magnet: A permanent magnet produces its own magnetic field.

The idea

A permanent magnet is made from a hard magnetic material such as steel, alnico or neodymium, and it produces its own magnetic field all the time. Its north and south poles are fixed, and they are there whether or not another magnet is anywhere near. That is the crucial contrast with an induced magnet, which is only magnetic while it sits inside somebody else's field. Because a permanent magnet has its own fixed poles, it can repel as well as attract, which an induced magnet can never do. It is not indestructible: heating it strongly, hammering it or dropping it repeatedly jumbles the domains and demagnetises it, but simply moving it away from other magnets does not.

What earns the marks

• Stating that a permanent magnet produces its own magnetic field.
• Stating that the field is present whether or not another magnet is nearby.
• Stating that the poles of a permanent magnet are fixed, so it can repel as well as attract.
• Contrasting with an induced magnet, which is magnetic only while it is in an external field.

Common mistakes and how to put them right

• Asserting that a permanent magnet can never lose its magnetism.

• Describing a permanent magnet simply as one that is always attracting things.

• Confusing a permanent magnet with an electromagnet, which needs a current.

• Saying a permanent magnet has no field until something magnetic is brought near it.

Exam tips

• Difference questions need both sides written out, not just the permanent magnet.
• Use the phrase 'produces its own magnetic field' word for word.
• Mention that only a permanent magnet can repel, as your test for telling them apart.