Magnets
A An object capable of exerting a magnetic force. can exert a force on another nearby magnet. Magnets have two poles:
- a In a magnet, the end that is attracted to the Earth's magnetic north pole.
- a In a magnet, the end that is attracted to the Earth's magnetic south pole.
The Able to be magnetised or attracted to a magnet. force is strongest near the magnet's poles.
The rules of magnetism
Two magnets will either attract or repel each other in the following way:
- like poles (N–N or S–S) repel
- unlike poles (N–S or S–N) attract
Magnetic forces are Force exerted between two objects, even when they are not touching, such as the force of gravity. – this means that magnets affect each other without touching.
Induced and permanent magnetism
Iron, steel, nickel and cobalt are magnetic materials. They are affected by magnets and are attracted to either pole of a magnet.
Permanent magnets
A Magnet made from a magnetic material. Its magnetism cannot be turned on or off, unlike an electromagnet. is often made from a magnetic material such as iron. A permanent magnet always causes a force on other magnets, or on magnetic materials. Key features of a permanent magnet:
- it produces its own magnetic field
- the magnetic field cannot be turned on and off – it is there all the time
Bar magnets and horseshoe magnets are examples of permanent magnets.
Induced magnets
Unlike a permanent magnet, an A temporary magnet, made from a magnetic material placed in a magnetic field. The induced magnetism is lost when moved out of the magnetic field. only becomes a magnet when it is placed in a magnetic field. The induced magnetism is quickly lost when the magnet is removed from the magnetic field.
Like all induced magnets:
- they are only attracted by other magnets, they are not repelled
- they lose most or all of their magnetism when they are removed from the magnetic field