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[Magnetism]

1. Magnet:-

Magnet is substance that always shows north and south direction when freely

suspended and attracts magnetic substances.

It is made by an iron compound called magnetite.

It was initially called as loadstone. It was first found in about 2500 years ago

in Greece and China by a shepherd.

2. Natural Magnet:-

The magnet that is made by the nature is called natural magnet.

For Example:-

Loadstone

3. Artificial Magnet:-

Those magnets that are made by the man for different purpose are called

artificial magnets.

For Example:-

Bar magnet

U- shaped magnet.

Horse Shoe Magnet.

Magnetic compass.

etc.

4. Types of Artificial Magnet:-

On the basis of shape different types of artificial magnets are available.

They are:-

Bar magnet

U shaped,

Horse-shoe magnet

Circular magnet

5. Use of Artificial magnet:-

Artificial magnets have various uses in our daily life.

So, some of the important uses of use of artificial magnet are as follows: -

· They can be made into any desired shape.

· They can be made too powerful as well.

· They can be made heavy as well as light on the basis of requirement. etc.

6. Magnetic materials:-

Those substances that are attracted by the magnet are called magnetic

materials.

For Examples:-

Iron

Cobalt

Nickel

Steel. etc.

7. Non Magnetic Materials:-

Those substances that are not attracted by a magnet are called mon- magnetic

materials.

For Example:-

Plastic

Gold

Silver

Glass. etc.

8. Properties of Magnet:-

Some important properties of magnet are as follows: -

· Magnet attracts magnetic substances only.

· A freely suspended magnet always shows north and south directions while coming to rest.

· Similar poles of two magnets repel while dissimilar poles of two magnet attract with each other.

· Poles of magnet always exist in a pair. That means two poles of magnet cannot be separated.

· Magnet has strong force of attraction at the poles and weak force at the middle.

· Every magnet has magnetic field around it.

etc.

9. Magnetic Field:-

A space around the magnet up to which its force of attraction can be felt on

the magnetic materials is called magnetic field.

10. Magnetization:-

The process of developing magnetic properties on the magnetic materials is

called magnetism.

Magnetic properties can be generated on the magnet due to following

activities: -

(i) By single Touch Method.

(ii) By double touch method.

(iii) By keeping a magnetic materials N-S direction below the surface

for some months.

(iv) By magnetic induction method.

(v) By electrical method.

(i) By single Touch Method:-

When a piece of iron rod is rubbed by a one pole of the permanent regularly for (60- 70) times, then magnetic properties are developed on it. In this way, magnet can be made temporarily. This method is called single touch method.

(i) Double Touch Method:-

When a piece of iron rod is rubbed by two opposite poles of permanent magnet from middle side of iron rod to away for (60 – 70) times, then magnetic properties are produced in this way magnetic properties are developed on it temporarily. This is called double touch method.

(i) By keeping a iron Rod below the earth to N-S direction:-

When a long iron rod is kept below the earth for about 5-6 months to north south direction, then magnetic proprieties are produced on it.

(ii) Magnetic Induction:-

The process of developing magnetic properties on the magnetic materials due

to presence of permanent magnet is called is called magnetic induction.

(iii) Electromagnet:-

If magnetic material becomes a magnet and produce magnetic properties on it

when electric current is passed through it, this is called electric method of

producing magnetic properties.

At that time used iron rod behaves like a magnet which is called electromagnet.

1. Way to increase the Strength of Electromagnet:-

There are some ways to increase the strength of electromagnet.

They are:-

· Strength of electromagnet can be increased by suppling more electrical energy in the circuit.

· Strength of electromagnet can be increased by increasing the number of turns of insulated wires.

· Strength of electromagnet can be increased by using soft iron core.

· Strength of electromagnet can be increased by decreasing the distance between two ends of the iron core.

2. Demagnetization:-

The process of losing magnetic properties from the magnet is called

demagnetization.

There are some ways that cause for the are as follows: -

· A magnet is demagnetized when it dropped regularly on the ground.

· A magnet is demagnetized when similar poles of two magnets are rubbed with each other.

· A magnet is demagnetized when it is heated.

· A magnet is demagnetized when it is stored without using keepers.

· A magnet is demagnetized when it is hammered by a hammer. Etc.

3. Conservation of magnetic strength:-

As we know that magnet can easily lose the magnetic properties. So, there are

some special methods for the conservation of magnetic strength.

They are as follows: -

· Magnetic strength of a magnet can be preserved by not dropping the magnet regularly on the ground.

· Magnetic strength of a magnet can be preserved by not heating the magnet.

· Magnetic strength of a magnet can be preserved by not rubbing two similar poles of magnets.

· Magnetic strength of a magnet can be preserved by storing with keepers.

· Magnetic strength of a magnet can be preserved by not breaking the magnet into small pieces.

· Magnetic strength of a magnet can be preserved by not hammering the magnet.

· Magnetic strength of a magnet can be preserved by preventing it from rusting. Etc.

4. Uses of Magnet:-

Some important uses of magnet are as follows: -

· They are used in the radio, speaker, television, dynamo, electric bell etc.

· It is used in the steel and iron factories to lift the heavy metal plates.

· It is used in the hospital to remove magnetic particles from their eyes.

· It is used to find the direction in the ships and aeroplanes. etc

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This content is contributed by:

Dipak Dangi