magnetism
Magnetic Materials
Magnetism
Magnetism describes the ability of magnets to attract (pull towards) and repel (push away) other magnets without touching them.
Attraction
Magnets have a north pole (N) and south pole (S).
If two magnets are close enough to each other, then the south pole of one magnet will attract the north pole of the other magnet.
This is an example of a non-contact force.
Repulsion
If one magnet is turned so that both south poles (or both north poles) are close together, then the magnets will repel each other.
Opposite poles on a magnet attract and like poles on a magnet repel. This is an example of a non-contact force.
The poles of a magnet
A magnet's poles are where the magnetic forces are strongest.
Iron, nickel and cobalt are the only pure metals that can be turned into a magnet. These metals are “magnetic materials”.
Properties of magnetic materials
Magnetic materials, like iron, don’t always act as magnets.
For example a normal piece of iron won’t attract (pull) or repel (push) another piece of iron.
But magnetic materials, like iron, are attracted to a magnet if they are close enough to the magnet.
Magnetic materials can be attracted by a magnet, but can’t be repelled by a magnet.
Only two magnets can repel each other.
Non-magnetic materials will never be attracted to magnets.
Permanent magnets are always magnetic, even when they are not near other magnets.
They produce their own magnetic field.
Induced Magnetism
A magnetic material will temporarily become a magnet when it is close to a permanent magnet. There is always an attractive force between an induced magnet (or magnetic material) and a permanent magnet.
Induced magnets are magnetic materials that become magnets when they are in a magnetic field.
When moved away from the permanent magnet, the magnetic material will stop being a magnet.
This is called induced magnetism.
Poles
The permanent magnet induces (creates) temporary poles in the magnetic material and these align so that the magnetic material is attracted to the permanent magnet.
If the north pole of the magnet is next to the magnetic material, then a south pole will be induced in the part of the material closest to the magnet.
Magnets
The key phrase to remember when thinking about magnet behaviour is: 'like poles repel, unlike poles attract'.
Like poles repel
Unlike poles attract