Fun with Magnets | Class 6 | Science | Chapter 15 | Maharashtra State Board
Get ready to have some fun with magnets! In this lesson, we will answer your biggest questions about magnets and explore their fascinating properties. We'll start by defining what magnets are and explaining the differences between magnetic and non-magnetic materials. Did you know that the story of magnets dates back to ancient Greece? We will travel back in time and discover the tale of Magnes, the Greek shepherd who discovered magnets. Moving on, we will learn about the different types of magnets, including permanent magnets and electromagnets. We will explore the characteristics of magnets and perform some cool electromagnet activities. We will also delve into the history of Michael Faraday, the inventor of electromagnetism. Magnetism is all around us, and we will show you how magnets are used in our day-to-day lives. From refrigerator magnets to MRI machines, we rely on magnets for many important functions. Finally, we will share tips on how to take care of your magnets and protect them from damage. So, come and join us in this exciting journey to learn about magnets!
Questions & Answers
1. How will you do this?
(a) Determine whether a material is magnetic or non-magnetic.
Ans. The material should be taken near to the magnet. If the material sticks to the magnet, the material is magnetic. If it does not stick then it is non-magnetic.
(b) Explain that a magnet has a certain magnetic field.
Ans. Keep a magnet in the centre of a paper. Spread iron filings uniformly on the flat paper. The iron filings will get attracted to the magnet only till a particular region. Beyond this region, the iron filings will not get attracted. The region where iron filings are attracted is the magnetic field, whereas the region from where the iron filings are not attracted, will be the region with no magnetic field. This experiment can give some idea about the extent of magnet field of a magnet.
(c) Find the north pole of a magnet.
Ans. Suspend a magnet freely in the air with help of a thread. The north pole of the magnet will point to the north direction while the south pole of the magnet will point to the south direction. If the directions are not known, then we can use mariner’s compass. Take a magnet near the mariner’s compass. The pole which shows repulsion if taken near the north pole of a mariner’s compass, will be the north pole of this magnet.
2. Which magnet will you use?
(a) Iron is to be separated from trash.
Ans. Electromagnet.
(b) You are lost in forest.
Ans. Mariner’s compass.
(c) A window shutter opens and shuts continuously in the wind.
Ans. Permanent magnet.
(d) The doorbell should ring.
Ans. Electromagnet.
3. Fill in the blanks with the appropriate word.
If a bar magnet is hung by a thread tied at its centre, its north pole becomes steady in the direction of the north pole of the earth. (South, north, east, west)
If a bar magnet is cut into equal pieces by cutting it at right angles to its axis at two places, 3 bar magnets are formed, and a total of 6 poles are formed. (6, 3, 2)
There is repulsion between the like poles of a magnet, and attraction between its opposite poles. (opposite, like).
When magnetic material is taken close to a magnet, the material acquires induced magnetism. (Permanent magnetism, induced magnetism).
If a magnet attracts a piece of metal, that piece must be made of magnetic material or iron. (any other metal but iron, magnetic material or iron, non magnetic material).
A magnet remains steady in a north-south direction. (east-west, north-south).
4. Write the answers in your words.
(a) How is an electromagnet made?
Ans. When an article of iron is wound by a copper wire and the electric current is sent through the wire, the magnetism is produced in this iron article. If the electric current is shut off, the magnetism is lost. This is how temporarily magnetism can be produced by creating electromagnetism.
(b) Write the properties of a magnet.
Ans. Properties of a magnet.
A magnet always settles in the north-south direction.
At the two poles of a magnet, the magnetic force is concentrated.
If a magnet is divided into two parts, it forms two independent magnets. Two poles of a magnet cannot be separated from each other.
Between the like poles of a magnet, there is repulsion, whereas between the opposite poles there is attraction.
(c) What are the practical uses of a magnets?
Ans. Properties of a magnet.
Pin holder, doorbell, doors of a fridge, car doors, magnets attached to a fridge for decorations are some of the articles in which magnets are used.
The crane uses magnets which are very powerful. They are usually electromagnets.
The modern medical technique such as MRI (Magnetic Resonance Imaging) also uses magnetism. ATM cards, credit cards and debit cards also have a magnetic strip attached to them.
E X T R A
1. Fill in the blanks.
A magnet always settles in north-south direction.
The magnetic force is concentrated at the two ends or poles of a magnet.
The material alnico is a mixture of aluminium, nickel and cobalt.
Magnetite is a natural magnet.
The bar of soft or pure iron used to protect magnets is called a magnet keeper.
2. State whether the following statements are true or false.
(a) The poles of a magnet can be separated.
Ans. False.
(b) After heating a magnet, its magnetism increases.
Ans. False.
(c) Electromagnetism is a permanent.
Ans. False.
(d) Magnetism is a kind of energy.
Ans. True.
(e) Permanent magnets are made from a mixture of nickel, cobalt, iron.
Ans. True.
3. Write short note.
(a) Induced Magnetism.
Ans.
Magnetism is a phenomenon by which a magnet exerts attractive or repulsive force on the other material.
A magnetic substance can acquire magnetism when brought near a magnet. This phenomenon is called Induced magnetism.
(b) Maglev train.
Ans.
Maglev (Magnetic Levitation) trains work on the principle of electromagnetism and repulsion.
Due to the repulsion between the train and the rail, the force of friction does not come into play and train slides over the rails with great speed.
The magnets fixed on the two sides of the train help it to move forward.
4. Define the following.
(a) Magnetic substance.
Ans. Substance that are attached towards a magnet are called Magnetic substances. e.g. Iron, nickel and cobalt.
(b) Non-magnetic substances.
Ans. Substance that are not attracted towards a magnet are called non-magnetic substances. e.g. Wood, rubber, plastic, etc.
5. Give scientific reasons.
(a) A magnet should be stored in a magnet keeper.
Ans.
A magnet loses it magnetism, if it is hammered, heated or if it falls down from the height and breaks into pieces.
To avoid this, pieces of soft iron called Magnet keepers are placed across the poles of the magnet.
The bar of soft or pure iron protects the magnet from getting demagnetized. Hence, magnet should be stored with the help of a Magnet keeper.
Hence, magnet should be stored with the help of a Magnet keeper.
(b) A magnetic needle is used in Mariner’s compass.
Ans.
A Mariner’s compass consists of a magnetic needle pivoted at a point so that it is free to rotate about that point.
This freely suspended magnetic needle always comes to rest in the north-south direction.
Hence, a magnetic needle is used in Mariner’s compass.
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