STD-6, CHAPTER-13: MAGNETS, EXERCISE QUESTION ANSWERS

 

A.     FILL IN THE BLANKS.

1.      The materials which do not get attracted towards a magnet are called _______.

Ans: non-magnetic substances

2.      The bar magnet is an example of a ______ magnet.

Ans: artificial

3.      Even the smallest piece of a bar magnet has two _____.

Ans: poles

4.      Earth has its magnetic _______ towards its geographical south pole.

Ans: north pole

5.      Magnets have been used for ______ purposes.

Ans: navigation

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      Naturally occurring magnets are called loadstones.                                             True

2.      An aluminium foil would get attracted by a magnet.                                           False

3.      Bar magnets have a ‘north seeking’ pole as well as a ‘south seeking’ pole.    True

4.      Two magnetic poles, of the same kind, attract each other.                                False

5.      When two magnets are moved farther apart from each other, the forces, that attract or repel them, tend to become stronger.                                                                                            False

C.      TICK THE CORRECT OPTION.

 

1.      The magnetic material, that was discovered first of all, is-

(a)   iron        (b) steel         (c) loadstone       (d) cobalt

      Ans: loadstone

2.      A magnet can attract-

(a)    a glass object             (b) a flower         (c)  a book         (d) an iron nail

      Ans: an iron nail

3.      A material, that is often used to make a temporary magnet, is-  

(a)   steel       (b)  alnico      (c)   ticanol     (d) soft iron

       Ans: soft iron

4.      When we suspend a bar magnet from a thread, it comes to rest along the–

(a)    North-west direction                                  (b)  east-west direction

(c)     South-west direction                                  (d) north-south direction

      Ans: north-south direction

5.      A device, which generally does not use a magnet, is-

(a)   A CD player                                    

(b)   A telephone

(c)    A geyser

(d)   An electric motor

      Ans: a geyser

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      State any two properties of a bar magnet.

Ans: Two properties of a bar magnet are, attractive property and directive property.

2.      Maximum iron filling stick to the two ends of a bar magnet. Why?

Ans: The magnetic strength is maximum at the two ends of a bar magnet. So, maximum iron fillings stick to the two ends of a bar magnet.

3.      Suppose we bring the north pole of one bar magnet towards the north pole of another freely suspended bar magnet. What are we likely to observe?

Ans: When we bring the north pole of one bar magnet towards the north pole of another freely suspended bar magnet, we will observe that the freely suspended magnet moves away. This is due to the fact that like poles repel each other.

4.      Two magnets X and Y, are placed as shown in the diagram. It is observed that magnet X floats above magnet Y. Give reason for this observation.

Ans: We know that the like poles of two magnets repel each other. Here also, the like poles of both the magnets are facing each other. Hence, the magnets are repelling each other. This is the reason the magnet X is floating above the magnitude Y.

5.      You are given a knitting needle made of steel. How can you make it into a magnet?

Ans: We can turn a knitting needle made of steel into a magnet by moving a bar magnet, along the length of the needle, a large number of times always in the same sense.

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      Distinguish between the following:

(a)   Permanent magnet and temporary magnet

Ans: Permanent magnet: These magnets retain their magnetic properties for a longer duration. Permanent magnets can be made using steel, cobalt steel, alnico and ticanol.

Temporary Magnet: These magnets retain their magnetism for a shorter period of time. Electromagnets are a commonly used form of temporary magnets.

(b)   Magnetic and non-magnetic materials

Ans: Magnetic Materials: Materials which get attracted towards a magnet are called as magnetic materials. Examples are cobalt, iron, nickel etc.

Non-magnetic Materials: Materials which do not get attracted towards a magnet are called non-magnetic materials. Examples are wood, plastic etc.

2.      Two bar magnets, ‘P’ and ‘Q’ are kept as shown in the following diagram.

(a) If point ‘c’ represents the south pole of the magnet Q, which point represents the north pole of magnet P?

Ans: As the two magnets are repelling each other, so we can say that the point ‘b’ and ‘c’ represent the like poles. Therefore, point ‘b’ of the magnet ‘P’ is south pole. Thus, the point ‘a’ of the magnet ‘P’ represents the north pole.

(b) What will happen when the end ‘d’, of magnet ‘Q’ is brought towards the end ‘b’ of magnet ‘P’?

Ans: As ‘c’ represents the south pole, so ‘d’ of magnet ‘Q’ is the north pole. So, when the ‘d’ end of ‘Q’ is brought towards the end ‘b’ of magnet ‘P’, they will attract each other.

3.      Describe, in brief, the construction of a compass needle. State its main use.

Ans: ‘The compass’ consists of a magnetic needle pivoted at its centre and free to rotate a horizontal plane. The needle is fitted in a horizontal box having a glass cover. The compass also has a dial with directions marked on it.

The compass needle always points in N-S direction and thus can be used for finding direction.

4.      Draw a labelled diagram to show the ‘proper way of storing two bar magnets’, when they are not in use. State the advantage of such a ‘proper storing’.

Ans: Advantage of proper storage of magnets:

(i) helps in preserving the magnetism in a magnet

(ii) helps in prolonging the life of a magnet

5.      Write the different ways through which magnets can be made to lose their magnetism.

Ans: Magnets can lose their magnetism in the following ways:

(i) by improper storage

(ii) by heating

(iii) by dropping

(iv) by hammering

6.      Anushtha saw a steel clip at the bottom of a very shallow puddle of water. She used a magnet, to take out this clip, without wetting her hands, or the magnet. Describe how she must have done this.

Ans: A magnet can attract an iron object even from a distance. Hence, Anushtha used the attractive property of magnet.