What is an electromagnet?
An electromagnet is a temporary magnet in which a long insulated copper wire is wrapped on a soft iron core in the form of a helix. Thus, an electromagnet is a solenoid having a core of soft iron core at its centre. When electric current in passed through it, it behaves as a magnet because a strong magnetic field is produced in it. An electromagnet is a temporary magnet because it behaves as magnet as long as the current is passed through it. Both the ends of electromagnet behave as north and south pole respectively. The polarity of an electromagnet can be reversed by reversing the flow of current through the coil. When the supply of current is stopped, the magnetism of electromagnet also disappears.
The strength of magnetic field produced in a solenoid depends upon following factors:
1. Strength of Current
The strength of magnetic field produced in a solenoid is directly proportional to the magnitude of current passing through it. Thus, strength of magnetic field increases if the magnitude of current passing through the solenoid is increased.
2. Number of Turns of Wire
Magnetic field can be increased by increasing the number of turns of copper wire in the solenoid.
3. Nature of Core
Magnetic field of a solenoid can be increased by using soft iron as core in the centre of solenoid.
Use of Electromagnets
Following are the uses of electromagnets:
1. Electromagnets are used to load and transport scrap iron, steel bars and machine parts.
2. Electromagnets are used in electric bells.
3. Electromagnets are used in telegraphs to send telegrams.