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Permanent & Induced Magnets (Edexcel IGCSE Physics: Double Science)
Revision Note
Permanent & induced magnets
Magnetic materials
Magnetic materials are attracted to a magnet; non-magnetic materials are not
- Magnetic materials are materials which are attracted by magnets
- Being a magnetic material does not mean the material is itself a magnet
- Very few metals in the periodic table are magnetic, these include:
- Iron
- Cobalt
- Nickel
- Steel is an alloy which contains iron, so it is also magnetic
- Magnetic materials will always be attracted to the magnet, regardless of which pole is held close to it
Magnetic materials attracted to either pole of a magnet
- To test whether a material is a magnet it should be brought close to a known magnet
- If it can be repelled by the known magnet then the material itself is a magnet
- If it can only be attracted and not repelled then it is a magnetic material
- There are two types of magnets
-
- Permanent magnets
- Induced magnets
Permanent magnets
- Permanent magnets are made out of permanent magnetic materials, for example steel
- A permanent magnet will produce its own magnetic field
- It will not lose its magnetism
Induced magnets
- When a magnetic material is placed in a magnetic field, the material can temporarily be turned into a magnet.
- This is called induced magnetism
- When magnetism is induced in a material:
- One end of the material will become a north pole
- The other end will become a south pole
- Magnetic materials will always be attracted to a permanent magnet
- This means that the end of the material closest to the magnet will have the opposite pole to magnets pole closest to the material
Inducing magnetism in a magnetic material
- When the magnetic material is removed from the magnetic field it will lose most/all of its magnetism quickly
Worked example
The diagram below shows a magnet held close to a piece of metal that is suspended by a light cotton thread. The piece of metal is attracted towards the magnet. 
Which of the following rows in the table gives the correct type of pole at X and the correct material of the suspended piece of metal?
| Type of pole at X | Material of suspended metal | |
| A | North | Nickel |
| B | South | Nickel |
| C | North | Aluminium |
| D | South | Aluminium |
Answer: A
- X must be a north pole
- The piece of metal is being attracted towards the magnet
- The law of magnetism states that opposite poles attract
- The material of the suspended piece of metal is nickel
- Nickel is a magnetic material (It will experience a force when it is placed in a magnetic field, in this case it is attracted towards the magnet)
- B is incorrect because X cannot also be a south pole (and hence is a north pole)
- If the pole at X was a south pole then the piece of metal would be repelled from the magnet because the law of magnetism states that like poles repel
- C and D are incorrect because aluminium is not a magnetic material
- A non-magnetic material would be unaffected by the magnetic field produced by the magnet.
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