Electromagnets are made using a coil of wire around an iron core (it can be an iron nail) and letting electricity flow through the wire. Here is a diagram of an electromagnet:
The concept is that the magnetic field around the wire (that is created by electric current flowing through it) can be strengthened by winding it into a coil and twisting around an iron core. There are ways to increase the strength of the electromagnet:
- Increasing the number of coils in the wire
- Increasing the current in the wire
- Using a magnetic material for the core
Have a look at a Maglev train in the picture below:
Electromagnets are used in Maglev trains. A computer system controls the current so the train stays 15cm above the track. The Maglev train is continually pulled forward, because the electromagnets on the tracks are turned on when they are just in front of the train, so they attract the train. As the train moves the next set of the electromagnets on the tracks is turned on and pull the train in turn.
Electric bells also contain an electromagnet. They are used in most schools.
When the current flows through, the electromagnet attracts the hammer. The hammer hits the gong and it makes a sound. The current is turned off and the hammer returns to its initial position.