Class ix > Physics > magnetism
What is an electromagnet?
An electromagnet is a temporary strong magnet made from a piece of soft iron when current flows in the coil wound around it.
The shapes of electromagnets
An electromagnet can be made in any shape, but usually, the following two shapes of the electromagnet are in use :
(i) I-shape (or bar) magnet, and
(ii) U-shaped (or horse-shoe) magnet.
(i) I-shape (or bar) magnet: I-shape electromagnet is a straight soft iron bar on which a thin insulated copper wire is wound in the form of a solenoid.
(ii) U-shape (or horse-shoe) magnet: U-shaped electromagnet is a U-shaped soft iron core on which a thin insulated copper wire is spirally wound on its arms.
Ways of increasing the magnetic field of an electromagnet
The magnetic field of an electromagnet can be increased by
(i) increasing the number of turns of winding in the solenoid
(ii) increasing the current through the solenoid.
Advantages of an electromagnet
(i) An electromagnet can produce a strong magnetic field.
(ii) The strength of the magnetic field of an electromagnet can easily be changed.
(iii) The polarity of the electromagnet can be reversed by reversing the direction of current in its solenoid.
Uses of electromagnets
(i) For lifting and transporting heavy iron scrap.
(ii) For loading the furnaces with iron.
(iii) For removing pieces of iron from a wound.
(iv) For separating the iron pieces from debris and ores.
Comparison of an electromagnet with a permanent magnet
|1. It is made of soft iron.||1. It is made of steel.|
|2. Its magnetic strength can be changed.||2. Its magnetic strength can not be changed.|
|3. Polarity can be reversed.||3. Polarity can not be reversed.|
|4. It can easily be demagnetised.||4. It can not be easily demagnetised.|