MP Board Class 6th Science Solutions Chapter 13 Fun with Magnets

MP Board Class 6th Science Solutions Chapter 13 Fun with Magnets

Fun with Magnets Textbook Exercises

Question 1.
Fill in the blanks in the following:

1. Artificial magnets are made in different shapes such as …………….. , …………….. and ……………..
2. The materials which are attracted towards a magnet are called ……………..
3. Paper is not a …………….. material.
4. In olden days, sailors used to find direction by suspending a piece of ……………..
5. A magnet always has …………….. poles.

1. Bar magnet, horse – shoe magnet, cylindrical.
2. Magnetic material
3. Plastic,
4. Suspended magnet
5. Two.

Question 2.
State whether the following statements are True (T) or False (F):

1. A cylindrical magnet has only one pole.
2. Artificial magnets were discovered in Greece.
3. Similar poles of magnet repel each other.
4. Maximum iron filings stick in the middle of a bar magnet when it is brought near them.
5. Bar magnets always point towards North – South direction.
6. A compass can be used to find East – West direction at any place.
7. Rubber is a magnetic material.

1. False
2. False
3. True
4. False
5. True
6. False
7. False.

Question 3.
It was observed that a pencil sharpener gets attracted by both the poles of a magnet although its body is made of plastic. Name a material that might have been used to make some part of it.
Iron.

Question 4.
Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting action between them for each situation. Fill in the blanks.

Question 5.
Write any two properties of a magnet.
The properties of a magnet are:

1. It attracts the objects made of iron, cobalt and nickle.
2. When it is suspended freely then it stands always in North – South direction.

Question 6.
Where are poles of a bar magnet located?
On the two ends of the bar magnet.

Question 7.
A bar magnet has no markings to indicate its poles. How would you find out near which end is its north pole located?
Take a bar magnet. Put a mark on one of its ends for identification. Now, tie a thread at the middle of the magnet so that you may suspend it from a wooden stand [Fig.]. Make sure that the magnet can rotate freely. Let it come to rest. Mark two points on the ground to show the position of the ends of the magnet when it comes to rest. Draw a line joining the two points. This line shows the direction in which the magnet Was pointing in its position of rest. Now, rotate the magnet by gently pushing one end in any direction and let it come to rest. Again, mark the position of the two ends in its position of rest.

Rotate  the magnet in other directions and magnet always comes to rest note the final direction in which it in the same direction comes to rest. We find that a freely suspended bar magnet always comes to rest in a North –  South direction. The end of the magnet that points towards North is called its North seeking end or the North pole of the magnet.

Question 8.
You are given an iron strip. How will you make it into a magnet?
Take the iron strip and place it on the table. Now take a bar magnet and place one of its poles near one edge of the bar of iron. Without lifting the bar magnet, move it along the length of the iron bar till you reach the other end. Now, lift the magnet and bring the pole (the same pole you started with) to the same point of the iron bar from which you began (fig.) Move the magnet again along the iron bar in the same direction as you did before.

Repeat this process about 30 – 40 times. Bring a pin or some iron filings near the iron bar to check whether it has become a magnet. If not, continue the process for some more time. Remember that, the pole of the magnet and the direction of its movement should not change. In this way, an iron strip can be converted into a magnet.

Question 9.
How is a compass used to find directions?
Magnetic Compass.
Magnetic compass consists of a small magnetized needle which is enclosed in a small round box made of aluminium. The box consists of a small pointed vertical axis (pivot) on which the magnetized needle rotates freely. The aluminium box is covered by thin glass cover.

The magnetized needle rotates freely and points towards geographic north from which true north can be calculated. This magnetic compass is used to find the direction at any place. Sailors and navigators also use this compass to find the direction during their journey.

Question 10.
A magnet was brought from different directions towards a toy boat that has been floating in water in a tub. Affect observed in each case is stated in Column I. Possible reasons for the observed affects are mentioned in Column II. Match the statements given in Column I with those in the Column II

(i) (d)
(ii) (e)
(iii) (b)
(iv) (a)
(v) (b).

Projects and Activities

Activity 1.
collect various objects of day – to – day use from your sourroundings. Test these with the “Magnes stick”. You can also take a magnet, touch these objects with it and observe which objects stick to the magnet. Prepare a table and record your observations.
Table: Finding the objects attracted by magnet

Fun with Magnets Text Book Questions

Question 1.
Boojho has this question for you. A tailor n was stitching buttons on his Shirt. The needle has slipped from his hand on to the floor. Can you help the tailor to find the needle?
Yes, with the help of magnet.

Question 2.
Paheli has this puzzle for you. You are given tow indentical bars which look as if they might be made of iron. One of them is a magnet, while the other is a simple iron bar. How will you find out, which one is a magnet?
The magnet has two poles where attraction is maximum. But in iron bar there is no pole, so attraction is same everywhere.

Fun with Magnets Additional Important Questions

Fun with Magnets Objective Type Questions

Question 1.
Question (i)
North pole of a magnet –
(a) Attracts north pole
(b) Remains inactive
(c) May attract or repel
(d) Repels north pole.
(d) Repels north pole.

Question (ii)
Which one is natural magnet –
(a) Ferrite
(b) Carbon
(c) Iron
(d) Magnetite.
(b) Carbon

Question (iii)
Which of the following is non – magnetic –
(q) Iron
(b) Nickel
(c) Cobalt
(d) Aluminium.
(d) Aluminium.

Question (iv)
An electrolyte is a –
(a) Solid that conducts electricity
(b) Liquid that does not conduct electricity
(c) Solid that does not conduct electricity
(d) Liquid that conducts electricity and breaks up chemically in the process.
(d) Liquid that conducts electricity and breaks up chemically in the process.

Question (v)
Strength of a magnet is –
(а) Maximum at centre
(b) Maximum at poles
(c) Minimum at poles
(d) None of these.
(а) Maximum at centre

Question 2.
Fill in the blanks:

1. Iron and nickle are …………….. materials whereas copper and aluminium are …………….. materials.
2. The regions of strongest magnetism in a magnet are known as the ………………
3. Like poles ………………. whereas unlike poles
4. The molecular magnets in a magnet are arranged in groups called ……………..
5. Steel is used to make …………….. magnets.
6. The shaving blade is an inexpensive ………………

1. Magnetic, non – magnetic
2. Ends
3. Repel, attract
4. Domains
5. Permanent
6. Magnet.

Question 3.
Which of the following statements are true (T) false (F):

1. The magnetite is mainly composed of oxides of iron.
2. Like poles of a magnet attract each other,
3. Plastic is a non – magnetic material.
4. A magnet looses its magnetism on striking voilently with hammer.
5. Magnets point towards East – West when freely suspended.
6. Earth behaves like a huge magnet.
7. Orested a Danish scientist noticed that a compass needle was affected by the electric current flowing in the neighbouring coil of wire.
8. The most important property of magnet is to attract iron pieces.
9. A horse – shoe magnet.can have only one pole.
10. A magnet can have two north poles.

1. True
2. False
3. True
4. False
5. True
6. True
7. True
8. Ture
9. False
10. False.

Question 4.
Match the items of Column A with Column B:

(i) (b)
(ii) (c)
(iii) (d)
(iv) (a).

Fun with Magnets Very Short Answer Type Questions

Question 1.
When was magnetite discovered?
Magnetite was discovered in 800 B. C.

Question 2.
From where a mineral magnetite was discovered first.
It was discovered in the town of Magnesia.

Question 3.
Why was magnetite named Londestone?
It was named so because this mineral can align itself in the same direction it left to rotate freely.

Question 4.
Which is the North Pole of a bar magnet?
It is the tip of a bar magnet which points towards the north direction.

Question 5.
Which is the South Pole of a bar magnet?
It is the tip of a bar magnet which points towards the south direction.

Question 6.
What is a temporary magnet?
It is piece of magnet only for a short period. This magnetism is lost as soon as the source of magnetisation is removed.

Question 7.
How should we store magnets?
We should store magnets by joining opposite poles of two magnets preferably with a piece of iron in between.

Question 8.
Who discovered the magnetic effects of electric current?
Danish Scientist H. C. Uersted discovered the phenomenon in 1820.

Question 9.
What are domains?
When we study a magnet in microscope, it consists of small regions. These regions are called domains.

Question 10.
How is magnet and electric current similar in property?
Because wires having electric current behave like a magnet. In electric current also like charges repel and unlike charges attract

.

Question 11.
What is a magnetic needle?
This needle moves a pivot fixed at the centre of a round frame box. It is used by navigators for finding out the direction in the sea.

Question 12.
Name some non-magnetic materials.
Plastic, cloth, paper and leather, etc. are non – magnetic materials.

Question 13.
What are the ends of a magnet called?
Poles.

Question 14.
What is natural magnet called?
Magnetite.

Question 15.
Which iron is used for making a permanent magnet?
Hard steel and alloys.

Question 16.
What is the instrument in which directive property of a magnet is used?
Mariner’s compass.

Fun with Magnets Short Answer Type Questions

Question 1.
What is a magnet? How is a temporary magnet different from a permanent magnet?
Any material that has the property of attracting iron is called a magnet.
Difference between temporary and permanent magnet:

Temporary magnet:

• It is magnet for a short period.
• Its magnetism is lost if source of magnetisation is removed.
• It is made up of soft iron.

Permanent magnet:

• It is magnet for ever.
• It remains magnet even if the source of magnetisation is removed.
• It is made up of steel.

Question 2.
Can you make out the south and north direction with the help of bar magnet. How?
Yes, we can make out the south and north directions with the help of bar magnet. Suspend a magnet from a string tied to its middle so that it can rotate freely. The tip of the bar magnet which point north will rest to the north direction and the tip bearing south will rest to point towards south direction.

Question 3.
Define magnetism. Also give the name of magnetic and non – magnetic substance.
Magnetism:
Magnet has the property of attracting various substances towards itself. This property of magnet is called magnetism.

Magnetic substances:
Those substances which are attracted by a magnet are called magnetic substances. For examples-, nickel, iron steel, cobalt and alloys of these substances are magnetic in nature.

Non – magnetic substances:
Those substances which are not attracted by a magnet are called non-magnetic substances. For examples, glass, cloth, wood, cloth, etc.

Question 4.
How can you make your personal compass?
Magnetise an iron needle using a bar magnet. Now, insert the magnetised needle through a small piece of cork or foam. Let the cork float in water in a bowl or a tub. Make sure that the needle does not touch the water (Fig.). Your compass is now ready to work.

Question 5.
What is an electromagnet? Give two applications of electromagnets?
When an electric current flows through a coil of wire, the coil behaves like a permanent magnet. When this current carrying coil is brought near a suspended bar magnet, one end of the coil repeals the north pole of the magnet. The other end of the coil attracts the north pole of the magnet. Thus, a current carrying coil has both a north and south pole like a magnet, such a magnet is called electromagnet.

Applications of electromagnet:

1. They are used in electric bells, telephones, telegraphps, etc.
2. They are used to separate magnetic substances like nickel, cobalt and iron from non – magnetic substances like brass, copper, zinc and plastics.

Fun with Magnets Long Answer Type Questions

Question 1.
What happens when the north pole of a magnet is brought near (i) the north pole, (ii) the south pole of a freely suspended magnet?

Suspend a bar magnet with a string. This bar magnet should be marked with north and south pole.

1. Hold another magnet in hand and bring its north pole close to each pole one by one. North pole of two magnet will repel each other as they are like poles.
2. While north of magnet, in hand comes close to south of suspended magnet, it will show attraction because they are unlike poles.

Question 2.
Can we have an isolated north pole or south pole?
An isolated magnetic pole is not possible. Two magnetic poles of a magnet cannot be separated.
If a magnet is broken into two pieces, each piece is a magnet having north and south pole. If these pieces are further broken into more smaller pieces, each piece consists the two poles (i.e., north pole and south pole) at its ends.

Dividing a magnet infinitely would still produce tiny magnets each having its own poles at two ends. This shows that two poles of a magnet cannot be separated and an isolated magnetic pole does not exist.

Question 3.
Explain the process by which a permanent magnet can magnetise an ordinary piece of iron?
A piece of iron can be magnetised by two methods:

1. By single touch method. Put a piece of iron on the table:
Hold a bar magnet on it vertically with north pole touching. Now move the magnet along the length. By repeating this practice many times makes that iron piece a magnet.

2. By double touch method:
Put a piece of iron on the table. Hold two bar magnets on it vertically with north and south pole of two magnets. Put them in the middle first. Move the magnets in opposite direction as shown in figure. Repeating this process converts the piece of iron into a magnet.

Question 4.
Why does a freely suspended magnet always come to rest in the north – south direction?
This is because the earth itself behaves like a huge bar magnet with its magnetic poles near the geographical north and south poles. The south pole of this bar magnet is near the geographical north pole, whereas the north pole of the bar magnet is near the geographical south pole.

In a freely suspended magnet, therefore, the north pole points towards the geographical north pole since it is attracted by the earth’s magnetic south pole. Similarly, the south pole of the suspended magnet is attracted by the earth’s magnetic north pole and, therefore, points towards the geographical south pole.

Question 5.
Write a short note on the cautions of magnets?