Electromagnets
Physics: Cambridge International GCSE Supplement, topic 4.1.6
Permanent Magnets and Electromagnets
You can create a magnet using a permanent magnet or by passing an electric current through a coil of wire (electromagnet).
Electromagnets
- An electromagnet is made from a cylindrical coil of wire that has an electric current passing through it.
- An electromagnet is only magnetic when there is an electrical current flowing through it.
- When the electric current is switched off, the wire immediately loses its magnetism (is demagnetised).
Permanent magnets
- Permanent magnets are usually made from steel.
- These materials have strong magnetic fields and it is hard to remove their magnetism.
Increasing the Strength of an Electromagnet
There are 3 ways to increase the strength of an electromagnet:
Iron core
- To increase the strength of an electromagnet you can place a soft iron core inside the solenoid (cylindrical coil of wire).
More coils
- To increase the strength of an electromagnet you can increase the number of coils of wire.
Higher electric current
- To increase the strength of an electromagnet you can increase the electric current flowing through the coils.
Test yourself on Electromagnets
What sort of material are permanent magnets usually made from?
Which of the following are true?
Which of the following are ways of increasing the strength of an electromagnet?
Which of the following properties will increase the strength of an electromagnet?