Physics Unit 7: Magnetism and electromagnetism
GCSE Revision Notes
Magnets:
All magnets have two poles – north
(north-seeking) and south (south-
seeking).
All magnets produce a magnetic field – a
region where other magnets or magnetic
materials experience a force.
Magnetism is a non-contact force, so
does not require contact to act.
The three magnetic materials are iron,
nickel and cobalt.
You can show a magnetic field by drawing magnetic
field lines. The lines always go from north to south and
they show which way a force would act on a north pole
if it was put at that point in the field.
The closer the field lines are, the stronger the magnetic
field. The further away from a magnet you get, the
weaker the magnetic field is. The magnetic field is
strongest at the poles of a magnet.
The force between a magnet and a magnetic material is
always attractive, no matter the pole.
If two like poles (e.g. north and north) are put together then they will repel, but if two
oppositely charged poles (e.g. north and south) are put together then they will attract.
Compasses show the directions of magnetic fields – inside a compass there is a tiny bar
magnet. The north pole of this magnet is attracted to the south pole of any other magnet it
is near, so the compass points in the direction of the magnetic field it is in.
When they are not near a magnet, compasses point north because the Earth generates its
own magnetic field, which shows the inside (core) of the Earth must be magnetic.
Permanent and induced magnetism:
There are two types of magnet – permanent magnets and induced magnets.
Permanent magnets produce their own magnetic field.
Induced magnets are magnetic materials that turn into a magnet when they’re put in a
magnetic field.
The force between permanent and induced magnets is always attractive. When you take
away the magnetic field, induced magnets quickly lose their magnetism and stop producing
a magnetic field.
Electromagnetism:
When a current flows through a wire, a magnetic field is created around the wire.
The field is made up of concentric circles perpendicular to the wire, with the wire in the
centre.
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GCSE Revision Notes
Magnets:
All magnets have two poles – north
(north-seeking) and south (south-
seeking).
All magnets produce a magnetic field – a
region where other magnets or magnetic
materials experience a force.
Magnetism is a non-contact force, so
does not require contact to act.
The three magnetic materials are iron,
nickel and cobalt.
You can show a magnetic field by drawing magnetic
field lines. The lines always go from north to south and
they show which way a force would act on a north pole
if it was put at that point in the field.
The closer the field lines are, the stronger the magnetic
field. The further away from a magnet you get, the
weaker the magnetic field is. The magnetic field is
strongest at the poles of a magnet.
The force between a magnet and a magnetic material is
always attractive, no matter the pole.
If two like poles (e.g. north and north) are put together then they will repel, but if two
oppositely charged poles (e.g. north and south) are put together then they will attract.
Compasses show the directions of magnetic fields – inside a compass there is a tiny bar
magnet. The north pole of this magnet is attracted to the south pole of any other magnet it
is near, so the compass points in the direction of the magnetic field it is in.
When they are not near a magnet, compasses point north because the Earth generates its
own magnetic field, which shows the inside (core) of the Earth must be magnetic.
Permanent and induced magnetism:
There are two types of magnet – permanent magnets and induced magnets.
Permanent magnets produce their own magnetic field.
Induced magnets are magnetic materials that turn into a magnet when they’re put in a
magnetic field.
The force between permanent and induced magnets is always attractive. When you take
away the magnetic field, induced magnets quickly lose their magnetism and stop producing
a magnetic field.
Electromagnetism:
When a current flows through a wire, a magnetic field is created around the wire.
The field is made up of concentric circles perpendicular to the wire, with the wire in the
centre.
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