NCERT Solutions: Fun With Magnets

Q1. Fill in the blanks in the following:
(i) Artificial magnets are made in different shapes such as ______, ______ and ______.
(ii) The Materials which are attracted towards a magnet are called ______.
(iii) Paper is not a ______ material.
(iv) In the olden days, sailors used to find direction by suspending a piece of ______.
(v) A magnet always has ______ poles.
Ans:
(i) Artificial magnets are made in different shapes such as bar magnet, cylindrical magnet and horseshoe magnet.

Cylindrical magnet

(ii) The materials which are attracted towards a magnet are called magnetic materials.

(iii) Paper is not a magnetic material.

(iv) In the olden days, sailors used to find direction by suspending a piece of bar magnet.

(v) A magnet always has two poles.

Magnet having two poles (North & South)

Q2. State whether the following statements are true or false.

Q3. 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 pencil sharpener is attracted to both poles of a magnet because some part of it is made of a magnetic metal. For example:

• The blade of the sharpener is usually made of iron or a steel alloy.
• Iron is a magnetic material, so the blade is attracted by the magnet even though the rest of the body is plastic.

Q4. 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.

Ans:

Q5. Write any two properties of a magnet.
Ans: Two important properties of a magnet are as follows:
(i) Like magnetic poles repel each other and unlike magnetic poles attract each other.
(ii) A freely suspended magnet always aligns itself in the north-south direction. It points roughly towards the geographical north and south.

Q6. Where are poles of a bar magnet located?
Ans: The poles of a bar magnet are located at its two end points. These ends show the strongest magnetic effect.

Two Poles

Q7. A bar magnet has no markings to indicate its poles. How would you find out near which end is its north pole located?
Ans: You can find the north pole of an unmarked bar magnet by doing the following:

• Hold or suspend the magnet so that it can turn freely.
• Wait until it stops moving; it will align itself along the north-south direction.
• The end that points towards the geographical north is the north pole of the magnet.
• The opposite end is the south pole.

Q8. You are given an iron strip. How will you make it into a magnet?
Ans: You can magnetise an iron strip by stroking it with a bar magnet as follows:

• Place the iron strip on a flat surface or hold it steady.
• Place one pole of a bar magnet at one end of the iron strip.
• Stroke the magnet along the strip towards the other end in a single direction without lifting it.
• Lift the magnet, return it to the starting point and repeat the same stroke in the same direction.
• Repeat this process about 30-40 times. This aligns the tiny magnetic regions in the iron strip and makes it a magnet.
• Test the strip by bringing a pin or a few iron filings close to it; if they are attracted, the strip has become magnetised.

Q9. How is a compass used to find directions?
Ans: A compass contains a small magnetic needle that can turn freely. The needle aligns itself in the north-south direction when the compass is kept level and still.

• The end of the needle that is painted red usually points to the geographical north; this indicates the north direction.
• The other end points to the south direction.

To use a compass, hold it flat so the needle can move freely, wait until it settles, and then read the direction indicated by the red end.

A Compass

Q10. A magnet was brought from different directions towards a toy boat that has been floating on water in a tub. The 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.

Ans:

Column I	Column II
Boat gets attracted towards the magnet.	Boat is made of magnetic material.
Boat is not affected by the magnet.	Boat is made of a 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 its direction.	Boat has a small magnet fixed along its length.