Class-6 Science, Chapter-13 Fun with Magnets , Additional exercises with solutions in line with NCERT book / CBSE Syllabus

Chapter 13
Fun with Magnets

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Exercises from textbook

Additional Exercises

Tables from Textbook

Activities/Projects

Additional Exercises

Choose the correct answer:

1.    The end of the magnet that points towards geographical north is called:

a.    North pole of the magnet (√)

b.    South pole of the magnet

c.     Can’t say

d.    Both (a) and (b)

2.    Magnets always come to rest in the ______direction.

a.    same (√)

b.    dfferent

c.    any

3.    A freely suspended bar magnet always comes to rest in _____ direction.

a.    north-south (√)

b.    east-west

c.    Both

4.    Magnets were found in a place called____

a.    Asia

b.    Magnesia (√)

c.    Netherland

5.    Rock of which material attracts iron?

a.    Magnet

b.    Magnesia

c.    Magnetite (√)

6.    Force that a magnet exerts is called______

a.    Magnetic force (√)

b.    Nuclear force

c.    Gravitational force

7.    Device which uses magnet to shoe direction is called_____

a.    Calipers

b.    Compass (√)

c.    Barometer

8.    Which of these uses magnets?

a.    Cabinet doors / door stoppers

b.    Refrigerator door

c.    Both (a) and (b) (√)

9.    Like poles exert the magnetic force of_________

a.    Attraction

b.    Repulsion (√)

c.    No action

10. Which of these is a magnetic material?

a.    Cobalt

b.    Nickle

c.    Both (√)

Science Class-7

Artificial magnets are prepared in different shapes. Identify the shapes of these magnets.

Fill in the blanks:

1.    Magnetite is a natural magnet.

2.    Magnet attracts materials like Iron, Nickel Cobalt.

3.    Each magnet has two poles - North and South.

4.    A freely suspended magnet always aligns in N- S direction.

5.    Opposite poles of two magnets attract each other whereas similar poles repel one another.

State whether the following statements are true or false:

a.    A magnets has two poles.                                                                  (True)

b.    North pole of the magnet attracts North pole of other magnet.         (False)

c.     Safety pin is a non-magnetic substance.                                           (False)

d.    Wood is a magnetic substance.                                                         (False)

e.    An iron nail is attracted by a magnet.                                                 (True)

Distinguish between magnetic and nonmagnetic substances.

Magnetic substances	Non-magnetic substances
The materials which get attracted towards a magnet are magnetic.	The materials which are not attracted towards a magnet are non magnetic.
For example iron, Cobalt or Nickel	For example paper, plastic or wood.

Answer these questions:

Q. What is a magnet?

Ans- The substances having property of attracting iron are known as magnet.

Q. What is an artificial magnet?
Ans- A magnet prepared from a piece of iron known as artificial magnet.

Q. What is a compass?
Ans- A compass is a small box with a glass cover on it. A magnetized needle is pivoted inside the box. This needle indicates the north-south direction when it comes to rest.

Q. When does a magnet loose it's properties?
Ans- A magnet looses it's properties when it is 
1- heated
2- hammered
3- dropped from some height
4- not stored properly

Q. How are magnets stored?
Ans- Magnets are stored as follows:
1 - Bar magnets should be kept in pairs with unlike poles on the same side. They must be separated by a piece of wood and two pieces of soft iron should be placed across their ends.

2- A piece of iron should be placed across the poles of a horse-shoe magnet.
3- Magnets should be kept away from cassettes, mobiles, televisions, music system, compact disks (CDs) and the computer.

Q. Few iron nails and screws got mixed with the wooden shavings while a carpenter was wrking with them. How can you help him in getting the nails and screws back from scrap without wasting his time in searching with his hands?

Ans- Nails and screws are magnetic substances. Carpenter can use a magnet to separate nails and screws from wooden shavings without wasting time in searching with his hands.

Give reason. Why?

Travelers carry magnet with them in olden days.
Ans- Travelers used to carry magnets with them to find the directions. They used to find direction by suspending natural magnets with a thread.

A freely suspended magnet always points in North-South direction.

A freely suspended magnet always point in North direction because earth itself behaves as a magnet. The shape of earth's magnetic field resembles that of imaginary bar magnet of length 1/5th of earth's diameter buried at its centre. The south pole of earth's magnet is in geographical north because it attracts the north pole of suspended magnet . Similarly , the north pole of earth's magnet is in geographical south because it attracts the south pole of the suspended magnet

Exercises from Textbook

Fill in the blanks:

1.    Artificial magnets are made in different shapes such as bar magnet, horseshoe magnet, cylindrical magnet and ball-ended magnet.

2.    The Materials which are attracted towards a magnet are called magnetic materials.

3.    Paper is not a magnetic material.

4.    In olden days, sailors used to find direction by suspending a piece of magnet.

5.    A magnet always has two poles.

State whether the following statements are true or false:

1.    A cylindrical magnet has only one pole.                                             False

2.    Artificial magnets were discovered in Greece.                                   False

3.    Similar poles of a magnet repel each other.                                      True

4.    Maximum iron fillings speak in the middle of a bar magnet when it is brought near them.                       

False

5.    Bar magnets always point towards north south direction.                 True

6.    A compass can be used to find east west direction at any place.     True

7.    Rubber is a magnetic material.                                                          False

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.

Ans- The Blade of a pencil sharpener is made up of iron. iron Is a magnetic material. Therefore a pencil sharpener gets attracted by both the poles of a magnet.
Column 1 shows different positions in which one pole of a magnet is placed near that of the other. Column 2 indicates the resulting action between them for each situation. Fill in the blanks.

Column 1	Column 2
N-N	Repulsion
N-S	Attraction
S-N	Attraction
S-S	Repulsion

Write any two properties of a magnet.
Ans- Following are the two properties of a magnet:
1- Magnet has two poles- North pole and South pole.

2- Like poles of magnets repel each other while unlike poles of magnets attract each other.
Where are poles of a bar magnet located?
Ans-  Poles of a bar magnet are located near the ends.

A bar magnet has no markings to indicate its poles. How would you find out near which end is its north pole located?
Ans-

We will freely suspended the bar magnet from a wooden stand and let it come to rest.
We will mark the direction in which magnet positions.This is north - south direction.

Using the sun we will find out direction north-south of Earth.

The end of the magnet that points towards north is called its North seeking end or the north pole.

The other end that points towards south is called South seeking and for the South Pole of the magnet.You are given an iron strip. How will you make it into a magnet?

Ans- We will make magnet by following the steps below:
1 – We will take a rectangular piece (bar) of iron and place it on the table.
2 – We will place one of the poles of a bar magnet near one edge of this bar of iron.
3 – Without lifting the bar magnet, we will move it along the length of iron bar till the other end.
4 – Now we will lift the magnet and bring the pole to the same point of iron bar from which we began.

5- We will repeat the same process about 30-40 Times.
6- Next, we will bring a pin near the iron bar to check whether it has become a magnet.
7 - If not, we will continue the process for some more time making sure that the pole of the magnet and the direction of its movement does not change.

How is a compass used to find directions?
Ans-

A compass is kept at the place where we wish to know the directions. It's a needle indicates the north south direction when it comes to rest. Compass is then rotated until the North and South marked on the dial are at the two ends of the needle.

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

Column I	Column II
Boat gets attracted towards the magnet.	Boat is fitted with a magnet with north pole towards its head.
Boat is not affected by a magnet.	Boat is fitted with a magnet with south pole towards its head.
Boat moves towards the magnet if north pole of the magnet is brought near its head.	Boat has a small magnet fixed along its length.
Boat moves away from the magnet when north pole is brought near its head.	Boat is made of magnetic material.
Boat floats without changing it direction.	Boat is made up of non magnetic material.

Ans-

Column I (Effect)	Column II (Cause)
Boat gets attracted towards the magnet.	Boat is made of magnetic material.
Boat is not affected by a magnet.	Boat is made up of non magnetic material.
Boat moves towards the magnet if north pole of the magnet is brought near its head.	Boat is fitted with a magnet with south pole towards its head.
Boat moves away from the magnet when north pole is brought near its head.	Boat is fitted with a magnet with north pole towards its head.
Boat floats without changing it direction.	Boat has a small magnet fixed along its length.

Tables from Textbook

Table 13.1 Finding the objects attracted by magnet

Name of the object	Material which the object is made of (Clothe / plastic / aluminium / wood/ glass / iron/ any other)	Attracted by Magnes stick / Magnet (Yes / No)
Iron ball	Iron	Yes
Scale	Plastic	No
Shoe	Leather	No
Staircase railing	Iron	Yes
Meter scale	Iron	Yes
Candy	Sugar	No
One rupee coin	Iron alloy	Yes
Pen	Plastic	No

Activity / Project

(1)  Using a compass, find the direction in which windows and entrance to your house or classroom open.

(2)  Try to place two equal sized bar magnets one above the other such that their north poles are o the same side. Note what happens and write your observations in your note book.

(3)  You can make an intelligent doll, which picks up the things it likes. Tale a doll and attach a small magnet in one of its hands. Cover this hand with small gloves so that the magnet is not visible. Now, your intelligent doll is ready. Ask your friends to bring different objects near the doll’s hand. Knowing the material of the object you can tell in advance whether the doll would catch it or not.

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