Correct Answer - Option 3 : Electric bell
Explanation:
Electromagnet:
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An electromagnet is a type of magnet in which the magnetic field is produced by an electric current.
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Electromagnets usually consist of wire wounds into a coil.
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The magnetism of the electromagnets can be increased by placing a soft iron rod inside the solenoid.
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The core of electromagnets is made of ferromagnetic materials which have high permeability and low retentivity.
- Electromagnets are used in electric bells, loudspeakers, and telephone diaphragms.
- Giant electromagnets are used in cranes to lift machinery, and bulk quantities of iron and steel
Permanent magnets are used in small motors and MRI
Soft iron is generally used for making electromagnets because it has high magnetic permeability, i.e. it can easily gain magnetic properties when current is passed around the core and quickly lose when current is stopped.
