Magnetism and Electromagnetism
Permanent and induced magnetism:
• Magnets have two poles – north and south.
• Magnets produce a magnetic field – a regions where other magnets or magnetic materials experience a
force.
• 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 together the lines are, the stronger the magnetic field.
The further away from a magnet you get, the weaker the field is.
• The magnetic field is strongest at the poles of a magnet.
• Opposite poles attract, like poles repel.
• Compasses show the directions of magnetic fields
o Inside a compass 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.
o You can move a compass around a magnet and trace its position on some paper to build up a
picture of what the magnetic field looks like.
o When they’re not near a magnet, compasses always point north. This is because the Earth
generates its own magnetic field, which shows the core of the Earth must be magnetic.
• There are two types of magnets
o Permanent magnets produce their own magnetic field.
o Induced magnets are magnetic materials that tun into a magnet when they’re put into a
magnetic field.
The magnetic field near a straight wire and Right-hand Rule:
• 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.
• Changing the direction of the current changes the direction of the magnetic field – use the right-hand
thumb rule to work out which way it goes.
o Using your right hand, point your thumb in the direction of current and curl your fingers. The
direction of your fingers is the direction of the field.
The magnetic field of a solenoid:
• A solenoid is a long coil of wire.
• The strength of the magnetic field produced by a solenoid can be increased by
o Using a larger current
o Putting more turns of wire
o Putting turns closer together
o Putting an iron core in the middle of a solenoid.
• Outside the coil, the magnetic field is just like a bar magnet.
• If you stop the current, the magnetic field disappears. A solenoid with an iron core is called an
electromagnet.
Electromagnetics:
Permanent and induced magnetism:
• Magnets have two poles – north and south.
• Magnets produce a magnetic field – a regions where other magnets or magnetic materials experience a
force.
• 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 together the lines are, the stronger the magnetic field.
The further away from a magnet you get, the weaker the field is.
• The magnetic field is strongest at the poles of a magnet.
• Opposite poles attract, like poles repel.
• Compasses show the directions of magnetic fields
o Inside a compass 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.
o You can move a compass around a magnet and trace its position on some paper to build up a
picture of what the magnetic field looks like.
o When they’re not near a magnet, compasses always point north. This is because the Earth
generates its own magnetic field, which shows the core of the Earth must be magnetic.
• There are two types of magnets
o Permanent magnets produce their own magnetic field.
o Induced magnets are magnetic materials that tun into a magnet when they’re put into a
magnetic field.
The magnetic field near a straight wire and Right-hand Rule:
• 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.
• Changing the direction of the current changes the direction of the magnetic field – use the right-hand
thumb rule to work out which way it goes.
o Using your right hand, point your thumb in the direction of current and curl your fingers. The
direction of your fingers is the direction of the field.
The magnetic field of a solenoid:
• A solenoid is a long coil of wire.
• The strength of the magnetic field produced by a solenoid can be increased by
o Using a larger current
o Putting more turns of wire
o Putting turns closer together
o Putting an iron core in the middle of a solenoid.
• Outside the coil, the magnetic field is just like a bar magnet.
• If you stop the current, the magnetic field disappears. A solenoid with an iron core is called an
electromagnet.
Electromagnetics:
