Notes on Magnetism | Grade 8 > Science > Magnetism | KULLABS.COM

## Magnetism (adsbygoogle = window.adsbygoogle || []).push({});

• Note
• Things to remember
• Videos
• Exercise
• Quiz

Magnets are generally of two types: natural magnets and artificial magnets. Natural magnets are naturally occurring magnets. Loadstone is an example of a natural magnet. Artificial magnets are the man-made magnets. Horseshoe shaped magnet and Bar magnet are the example of artificial magnets.

#### Properties of magnets

• A magnet has the ability to attract magnetic properties.
• A freely suspended magnet points North-South direction.
• Like poles repel and unlike poles attract.
• The magnetic poles cannot be separated by breaking the magnet.

#### Molecular theory of magnetism

Molecular theory of magnetism states, "If molecular magnets align in a row, then the substance exhibits magnetic property. If they are kept haphazardly, they do not exhibit magnetic property." This is the molecular theory of magnetism.

If molecular magnets align in a row, then the substance exhibits magnetic property. If they are kept haphazardly, they do not exhibit magnetic property. This is the molecular theory of magnetism. The poles of a magnet cannot be separated even by breaking into pieces because they exist in a pair and every molecule of a magnet has poles in the pair.

#### Evidence of molecular theory of magnetism

1. The poles of a magnet cannot be separated.
2. A magnet has more force at its ends than in the middle.
Reason: The molecular magnets are arranged in an open chain so that the north pole or the south pole of molecular magnets lie in the same direction which gives strong force at the poles whereas two opposite poles are arranged at the middle and the force cancel each other. So, poles have more force than the middle portion.
3. Only magnetic bodies can be magnetised.
4. A magnet gets demagnetized by
• Dropping regularly from a certain height
• Hammering a magnet
• By heating a magnet
• Rubbing the same pole, etc

• Magnets are generally of two types: natural magnets and artificial magnets.
• Molecular theory of magnetism states, “If molecular magnets align in a row, then the substance exhibits magnetic property. If they are kept haphazardly, they do not exhibit magnetic property."
• If molecular magnets align in a row, then the substance exhibits magnetic property.
• A magnet gets demagnetized by Dropping regularly from a certain height, Hammering , Rubbing the same pole, etc
.

### Questions and Answers

#### Click on the questions below to reveal the answers

Magnet which is formed naturally is called natural magnet. Man- made magnets are called artificial magnet. For instance,  Bar magnet, U-shaped magnet, etc.

The molecules of the magnetic substance retain the magnetic property. They are known as molecular magnets.

If molecular magnets align in a row, then the substance exhibits magnetic property. If they are kept haphazardly, they do not exhibit magnetic property. This is the molecular theory of magnetism.

Two poles of a magnet are of equal strength because the number of free north poles at one end is equal to the number of free south poles at the other end.

The poles of a magnet cannot be separated even by breaking into pieces because they exist in a pair, every molecule of a magnet has poles in a pair.

A magnet has molecules aligned in the same direction which provides it the magnetic property.

Though an iron is made up of molecular magnets, it does not have magnetic property because the molecules of iron are not aligned in the same direction and until the molecules are not arranged in the same direction, substance does not get magnetic property.

The molecular magnets are arranged in an open chain so that the north pole or the south pole of the molecular magnets lie in the same direction which gives strong force at the poles whereas two opposite poles are arranged at the middle and the force cancel each other. So, poles have more force than the middle portion.

It is because the molecules of the magnetic substance are not in the same direction.

Molecular magnets of magnetic substance are laid in same direction or open chain.

0%

four

six

three

two

Earth

Matter

Magnetite

Sun

• ### Which is false regarding to magnetism?

Force of attraction of a magnet is concentrated in the centre
Force of attraction increases as magnets are brought near each other
There is a north pole and a South pole
The end of a magnet are called poles
• ### Which is not a term related to magnets?

Length of magnet
Poles of magnet
Volume of magnet
Magnetic axis
• ### ______ is an example of natural magnets.

Loadstone

U-shaped magnet

Bar magnet

Horse shoe

## ASK ANY QUESTION ON Magnetism

You must login to reply

Forum Time Replies Report
##### show 9.1 experiment

You must login to reply

##### purushottam thakur

why copper piece cannot be made magnet?

You must login to reply

##### What evidence can be given for terrestrial magne

What evidence can be given for terrestrial magnetism

You must login to reply

You must login to reply