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LESSON NOTES:
ELECTROMAGNET
An electromagnet is a temporary strong magnet and is just as a solenoid with its winding on a soft
iron core.
An electromagnet consists of a soft iron core AB placed inside a solenoid. The current in the
solenoid can be adjusted with a rheostat Rh in the circuit having a battery and a key, K as shown in
figure. An electromagnet acquires the magnetic properties only when an electric current is passed
through the solenoid. Once the current is switched off, it almost loses its magnetic properties as
the retentivity (the ability to retain magnetism) of soft iron is very low.
The strength of the electromagnet depends upon:
(i) Amount of current flowing.
(ii) Number of the circular turns of wire.
In order to provide a strong magnetic field in a small region, an electromagnet is made in the U-
shape. Such a magnet is called a horse- shoe magnet.
Uses of Electromagnets
(i) Electromagnets are used in electrical devices such as an electric bell, an electric fan, telegraph,
an electric train, an electric motor, generator etc.
(ii) For lifting and transporting large masses of iron in
the form of girders.
(iii) In medical practice, for removing pieces of iron
