IGCSE Physics / Magnetism and electromagnetism
Magnets and magnetic materials
Edexcel International GCSE Physics (4PH1), chapter 20: Magnetism and electromagnetism, specification point 6.2, 6.5, 6.1. Free lesson.
Read the revision notes · IGCSE Physics past papers
Magnets have north and south poles, and only some materials are attracted to them. Knowing how poles interact and how induced magnetism works helps you identify magnets and explain how they attract magnetic materials.
How the poles of a magnet act
A magnet’s magnetic effect is strongest at its ends, called poles. A bar magnet has a north pole (N) and a south pole (S). If a magnet hangs freely, its north pole turns to point north. Like poles repel: N pushes N away, and S pushes S away. Unlike poles attract: N and S pull together.
Which materials are magnetic
A magnetic material is attracted by a magnet, even if the material is not itself a magnet. Learn the names of the four magnetic materials. Most metals are not magnetic, so writing only “metal” is not precise enough. The magnetic materials are iron, steel, nickel and cobalt. Copper, aluminium and brass are non-magnetic. They are not attracted by a magnet.
How to tell a magnet from iron
A magnet and a piece of unmagnetised iron can look the same. Test each with a known magnet. Iron is always attracted, whichever pole you bring near it. A magnet may be attracted or repelled, depending on the poles. Therefore, only repulsion proves that an object is a magnet. Attraction alone does not tell you whether the object is a magnet, because iron is attracted too. A magnetic material such as iron is never repelled by a magnet.
How induced magnetism makes a chain
When a magnetic material is in a magnet’s magnetic field, it can become a magnet itself. This is called induced magnetism. The induced poles are arranged so that the material is attracted to the magnet, allowing it to pick up another clip. A steel paper clip near a magnet’s north pole becomes a magnet. The end nearest the north pole becomes south, so the clip is attracted to the magnet. The far end becomes north. It magnetises the next clip in the same way, making a chain. Induced magnetism always gives attraction, never repulsion.