Magnets create a magnetic force between one another and between themselves and magnetic materials.
Magnetism
Magnets can attract and repel one another. They also attract magnetic materials.
Magnetic materials are attracted to magnets but not to each
other. Examples of magnetic materials are; iron, steel and nickel.
Non-magnetic materials are not affected at all by magnets.
The magnetic force passes through
non-magnetic materials but not
through magnetic materials.
The ends of magnets are called
poles. The south-seeking pole
points south and the north
seeking pole points north.
A north-seeking pole and a
south-seeking pole attract
each other, but two
south-seeking poles or two
north-seeking poles repel
each other.
Magnetic Field
The area around magnets is called the magnetic field. Magnetic field lines can be plotted with a compass.
The direction of the magnetic field goes from the magnet's north pole to its south pole.
Stronger magnets are represented by showing more lines of force around them.
The Earth behaves as if it
had a giant magnet inside it.
The
magnet in a
compass
lines up
with the
Earth's
magnetic
field.
Own magnet
You can make your own magnet by stroking an iron nail with one end of a magnet.
Electromagnet
When an electric current flows through a wire, the wire behaves like a weak magnet.
Magnets made using electricity are called electromagnets. These contain a
core, usually of iron, and a coil of wire which carries an electric current.
Electromagnets are very useful because they can be switched on and off.
You can change the strength of an electromagnet by changing the size of
the current, coiling the wire or placing a piece of iron inside the coil of wire.
Relays
Relay switches use the current from one circuit to switch on the current in another circuit.
A relay switch has an electromagnet in one circuit next to an iron switch in the other circuit.