MAGNETS
What are bar magnets?
Magnet: a piece of material that can attract other magnetic material
Bar magnets are permanent magnets. This means that their magnetism is there all the time and cannot be turned on or off. They have two poles:
▪ north pole (or north-seeking pole)
▪ south pole (or south-seeking pole).
The north pole is normally shown as N and the south pole as S.
What are magnets made of?
Magnets are made from magnetic materials. These are metals that can be magnetised or will be attracted to a magnet. Most materials are not magnetic, but iron, cobalt and nickel are magnetic. Steel is mostly iron, so steel is magnetic too.
Do magnets just attract?
No, they attract and repel.
If you bring two bar magnets together, there are two things that can happen:
· if you bring a north pole and a south pole together, they attract
· if you bring two north poles together, or two south poles together, they repel and the magnets push each other away.
We say that unlike poles attract, and like poles repel.
What are bar magnets?
Magnet: a piece of material that can attract other magnetic material
Bar magnets are permanent magnets. This means that their magnetism is there all the time and cannot be turned on or off. They have two poles:
▪ north pole (or north-seeking pole)
▪ south pole (or south-seeking pole).
The north pole is normally shown as N and the south pole as S.
What are magnets made of?
Magnets are made from magnetic materials. These are metals that can be magnetised or will be attracted to a magnet. Most materials are not magnetic, but iron, cobalt and nickel are magnetic. Steel is mostly iron, so steel is magnetic too.
Do magnets just attract?
No, they attract and repel.
If you bring two bar magnets together, there are two things that can happen:
· if you bring a north pole and a south pole together, they attract
· if you bring two north poles together, or two south poles together, they repel and the magnets push each other away.
We say that unlike poles attract, and like poles repel.
How can you test if a piece of metal is a magnet?
Seeing if it sticks to a magnet is not a good test, because unmagnetised iron, steel, cobalt and nickel objects will be attracted to either pole of a magnet.
So you can't test for what it is attracted to. But you can test what it repels: You show that an object is a magnet if it repels another magnet
What is magnetism and what are magnetic fields?
Magnets create magnetic fields. These cannot be seen. Magnetism: a non-contact force, it acts at a distance.
The magnetic fields fill the space around a magnet where the magnetic forces work, where they can attract or repel magnetic materials.
The Earth has a magnetic field because it has an iron core.
Seeing if it sticks to a magnet is not a good test, because unmagnetised iron, steel, cobalt and nickel objects will be attracted to either pole of a magnet.
So you can't test for what it is attracted to. But you can test what it repels: You show that an object is a magnet if it repels another magnet
What is magnetism and what are magnetic fields?
Magnets create magnetic fields. These cannot be seen. Magnetism: a non-contact force, it acts at a distance.
The magnetic fields fill the space around a magnet where the magnetic forces work, where they can attract or repel magnetic materials.
The Earth has a magnetic field because it has an iron core.
What are Electromagnets?
When an electric current flows in a wire it creates a magnetic field around the wire.
By winding the wire into a coil we can strengthen the magnetic field. Electromagnets are made from coils like this.
Making an electromagnet stronger
We can make an electromagnet stronger by doing these things:
▪ wrapping the coil around an iron core
▪ adding more turns to the coil
▪ increasing the current flowing through the coil.
Does an electromagnet have a magnetic field?
Of course. The magnetic field around an electromagnet is just the same as the one around a bar magnet. It can, however, be reversed by turning the battery around.
Unlike bar magnets, which are permanent magnets, the magnetism of electromagnets can be turned on and off just by closing or opening the switch
When an electric current flows in a wire it creates a magnetic field around the wire.
By winding the wire into a coil we can strengthen the magnetic field. Electromagnets are made from coils like this.
Making an electromagnet stronger
We can make an electromagnet stronger by doing these things:
▪ wrapping the coil around an iron core
▪ adding more turns to the coil
▪ increasing the current flowing through the coil.
Does an electromagnet have a magnetic field?
Of course. The magnetic field around an electromagnet is just the same as the one around a bar magnet. It can, however, be reversed by turning the battery around.
Unlike bar magnets, which are permanent magnets, the magnetism of electromagnets can be turned on and off just by closing or opening the switch