Maharashtra Board Class 6 Science Chapter 15 Fun with Magnets PDF Download

Fun With Magnets

Can You Tell?

1. Pins in a pin holder do not fall even when it is held upside down. Why is this so?

2. While we are shutting the door of a fridge, we find that it closes automatically from a certain distance and does not open unless pulled again. Why is this so?

A magnet is used in these gadgets. A magnet is fitted in the cap of a pin holder and in the door of a fridge. Iron objects stick to a magnet.

What Is A Magnet?

The material to which objects made from iron, nickel, cobalt, etc. get attracted is called a magnet. This property of a material is called magnetism.

Let's Try This

1. Take a magnet from the laboratory and bring it near various objects in your use. Which of them stick to the magnet? What material is each of them made of? Observe these things carefully. Classify the objects into two groups: those which stick to the magnet and those which do not.

2. Take a mixture of sand, pieces of paper, sawdust, iron filings and pins in a saucer and pass a magnet around the mixture. What do you see?

The materials that stick to a magnet are called magnetic materials, while those that do not stick to a magnet are called non-magnetic materials. The metals iron, cobalt, nickel are magnetic materials.

Teacher's Note

Magnets are very useful in our daily life. For example, the door of your refrigerator at home has a magnet inside that keeps it closed.

Exam Trick

Remember: Magnetic materials stick to a magnet. Iron, nickel, and cobalt are magnetic metals. Non-magnetic materials do not stick to a magnet.

Points to Remember

A magnet pulls things made of iron, nickel, and cobalt.
Magnetic materials stick to a magnet.
Non-magnetic materials do not stick to a magnet.
Magnetism is a special power that magnets have.

In The Past...

There is a legend about the discovery of magnets. It is said that a shepherd named Magnes lived in Greece. Once, while his sheep were grazing, he sat down on a big rock. But, what a surprise he got when he tried to get up! His staff and his shoes were stuck to the rock. He had to use great force to pull himself away from the rock.

He realized that what had happened was because of the iron ferrule on his staff and the iron nails in his shoes. However, other rocks did not stick to his shoes or staff. Later, he showed the rock to everybody.

The rock was named magnetite after Magnes, the shepherd. Magnetite is a natural magnet. It is also possible that the name magnet came from Magnesia, the part of Greece where magnets were discovered.

It was known quite long ago to the people in China and Europe that a piece of magnetite, hung freely, always settled in the north-south direction. These rocks then came to be used for finding the directions while travelling through unknown regions. That is why, they are also called lodestones (leading stones). This led to the invention of the mariner's compass.

Find Out

How is a mariner's compass used?

Magnets can have a variety of shapes depending upon their uses. Today, magnets are used in many machines and gadgets or devices. They are all man-made magnets. Find out where the magnets shown in the pictures below are used.

Bar magnets, disc magnets, horseshoe magnets, ring-shaped magnets, cylindrical magnets as also small button magnets are the different shapes of magnets in everyday use.

Teacher's Note

Long ago, people in China and Europe discovered that magnetite always points north-south. This is how the compass was invented. Today we use magnets in many things like speakers, phones, and toys.

Exam Trick

Remember: Magnetite is a natural magnet found in nature. The name magnet came from a shepherd named Magnes or from Magnesia in Greece.

Points to Remember

Magnets were discovered a very long time ago.
A shepherd named Magnes discovered magnetite by accident.
Magnetite is a natural magnet that always points north-south.
The compass was invented because of magnets.
Magnets have many different shapes today.

Magnetism

When a magnet attracts an object, that object is displaced due to the magnetic force. In places like factories, ports, garbage depots, large objects are shifted from place to place. For this purpose, cranes with magnets are used. Work is done by magnetic force. This shows that magnetism is a kind of energy.

Characteristics Of A Magnet

Let's Try This

1. Determine the directions in the class or laboratory. Tie a thread to the centre of a bar magnet and hang it from a stand. Note the direction in which the magnet settles and turn it around again. Let it settle and note the direction. Do this many times.

What do you observe?

A magnet always settles in the north-south direction.

The end of a magnet that points to the north is called the north pole while the end that points to the south is called the south pole. The north pole is indicated by N and the south pole, by S.

2. Place some iron filings on a sheet of paper and pass a bar magnet over them. Pick up the bar magnet by holding it in the centre. What do you see?

To which part of the magnet do most of the iron filings stick? On which part do we see fewer filings? What can we conclude from this?

The magnetic force is concentrated at the two ends or poles of a magnet.

3. Take a bar magnet that can be cut with scissors or a knife. Take iron filings on a sheet of paper and place the magnet on it. Most of the iron filings will be seen to stick to its poles.

Now cut the magnet into two pieces as shown in the picture and place those pieces on iron filings. Pick up each of the pieces and observe them.

What do you find?

If a magnet is divided into two parts, two independent magnets are formed. It means that the two poles of a magnet cannot be separated from each other.

Teacher's Note

A magnet always points north-south because the Earth itself is a big magnet. Just like a compass, a magnet hanging freely will always show you the direction.

Exam Trick

Remember: North pole points to Earth's north. South pole points to Earth's south. The strongest part of a magnet is at the poles. You can identify poles by the letter N and S.

Points to Remember

A magnet always settles in the north-south direction when it is free to move.
The north pole is marked with N and the south pole is marked with S.
The magnetic force is strongest at the poles of the magnet.
If you cut a magnet in half, you get two smaller magnets, not one magnet and one non-magnet.
The poles of a magnet cannot be separated from each other.

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