Magnetism is the property of attracting iron, cobalt, nickel and other magnetic substances. The material that shows this property is called the magnet. Lodestone is an example of a naturally occurring magnet. Magnets can also be prepared artificially by rubbing a ferromagnetic material with a strong magnet, by keeping the material in a magnetic field of a solenoid or by keeping it in contact with the pole of a magnet for a long time.
|Artificial magnets are of two types- Permanent magnets and Temporary magnets. Normally magnets are used in the form of bars.|
Bar magnets have the following basic properties.
Property 1: Attractive property
Magnets attract ferromagnetic materials like iron, cobalt and nickel. The strength of attraction is maximum at the poles and minimum at the midpoint of the bar magnet.
Property 2:Directional property
If the bar magnet is suspended freely using a thread, it always comes to rest in the geographically North-South direction.
Property 3: Magnets exist as a dipole
Magnets always exist as a dipole. Existence of monopole is not possible.
Property 4: Attraction and repulsion
Like poles repel each other and unlike poles attract each other.
Property 5: Equality of pole strength
The strength of both poles is always the same.
Property 6: Magnetic induction
When a magnetic material is kept in contact with a bar magnet it acquires the magnetic property. This process is called magnetic induction.
Property 7: Demagnetization
A magnet loses its magnetism when heated, beaten hard with a hammer or kept under the influence of AC current.
Property 8: Repulsion of materials
Some materials like gold, silver and water get repelled by magnets. These materials are called diamagnetic materials.