Electromagnet:
An electromagnet works on the magnetic effect of current. An electric current can be used for making temporary magnets known as electromagnets.
As electromagnet is a magnet having of a long coil of insulated copper wire wrapped around a soft iron core that is magnetised only when electric current is passed through the coil.
Note:-Soft iron is more suitable than steel for cores of electromagnets.
When we pass current through the solenoid, a magnetic field is set up in the space within the solenoid. The ends of the solenoid at which the current in the solenoid seems to flow anticlockwise acts an N-Pole and other one as S-Pole when the current in the magnetism almost completely due to its low retentivity.
Note:-The high permeability of soft iron increases the field one thousand times.
Factors affecting the strength of an Electromagnet:-
- The number of turns in the coil:-If we increase the number of turns in the coil, the strength of electromagnet increase.
- The current flowing in the coil:-If the current in the coil is increased, the strength of electromagnet increase.
- The length of air gap between its poles:-If we reduce the length of air gap between the poles of an electromagnet, then its strength increase.
Example:-The air gap between the poles of a bar type electromagnet is quite large, so a bar type electromagnet is not very strong. On the other hand, the air gap between the poles of a U-shaped electromagnet is small, so it is a very strong electromagnet.
Uses of Electromagnets:-
- Electromagnets are used in electric bells, loud-speakers and telephone diaphragms.
- Large electromagnets are used in cranes to lift heavy machinery and bulk quantities of iron and steel.
- In hospitals, electromagnets are used to remove iron or steel bullets from the human body.
- Electromagnets are used in Maglev train.