Exploring Magnets — Class 6 Science
Curiosity · Chapter 4
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5- Mathematics
- Science
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- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
Chapter summary
Key ideas & terms
- Magnetic materials
- Materials that are attracted towards a magnet, such as iron, nickel, and cobalt.
- Non-magnetic materials
- Materials that are not attracted towards a magnet, such as wood, plastic, rubber, and glass.
- Poles of a magnet
- The two ends of a magnet — the North pole and the South pole — where its attracting power is the strongest; poles always exist in pairs.
- Magnetic compass
- A small device with a freely rotating magnetic needle that comes to rest in the north-south direction and is used for finding directions.
- Attraction and repulsion
- Unlike poles of two magnets attract each other while like poles repel each other; repulsion is a sure test of a magnet.
- Earth as a magnet
- The fact that the Earth itself behaves like a giant magnet, which is why a freely suspended magnet rests along the north-south direction.
Extra questions & answers
What are magnetic and non-magnetic materials?
Magnetic materials are those attracted towards a magnet, such as iron, nickel, and cobalt, while non-magnetic materials are not attracted, such as wood, plastic, and glass.
Where is the attracting power of a magnet strongest?
The attracting power of a magnet is strongest at its two ends, called the poles, where most iron filings cling.
How many poles does a magnet have, and can a single pole exist?
A magnet always has two poles, a North pole and a South pole; a single pole cannot exist, because breaking a magnet only produces smaller magnets each with both poles.
Why does a freely suspended magnet rest in the north-south direction?
Because the Earth itself behaves like a giant magnet, so a freely suspended magnet always comes to rest along the north-south direction.
What is a magnetic compass used for?
A magnetic compass is used for finding directions; its freely rotating needle comes to rest pointing in the north-south direction.
What happens when like poles and unlike poles of two magnets are brought close?
Like poles (North-North or South-South) repel each other, while unlike poles (North-South) attract each other.
Which property is a sure test of whether an object is a magnet?
Repulsion is the sure test: a true magnet will repel one pole of another magnet, whereas a piece of iron is only ever attracted.
Can the magnetic effect pass through non-magnetic materials?
Yes; a compass needle is still deflected when wood, cardboard, plastic, or glass is placed between it and a magnet, showing the magnetic effect acts through non-magnetic materials.
How can you make an iron needle into a magnet?
By stroking the needle many times in the same direction with one pole of a magnet, then testing it by seeing if it attracts iron filings or pins.
How should magnets be stored and cared for?
Magnets should not be heated, dropped, or hammered, should be kept away from mobile phones, and should be stored in pairs with unlike poles together and soft iron pieces across their ends.
Let us enhance our learning
1. Fill in the blanks (i) Unlike poles of two magnets ______ each other, whereas like poles ______ each other.
Unlike poles of two magnets attract each other, whereas like poles repel each other. Opposite poles pull towards each other and same poles push away.
1. Fill in the blanks (ii) The materials that are attracted towards a magnet are called ______.
The materials that are attracted towards a magnet are called magnetic materials. Examples are iron, nickel and cobalt and many alloys containing them.
1. Fill in the blanks (iii) The needle of a magnetic compass rests along the ______ direction.
The needle of a magnetic compass rests along the north-south direction. When freely suspended it aligns approximately along the geographic north-south line because Earth behaves like a large magnet.
1. Fill in the blanks (iv) A magnet always has ______ poles.
A magnet always has two poles - a North pole and a South pole. They always exist in pairs, even if the magnet is broken into small pieces.
2. State whether the following statements are True (T) or False (F). (i) A magnet can be broken into pieces to obtain a single pole. [ ]
False. A single isolated North or South pole cannot exist. Every piece obtained on breaking a magnet still has both a North and a South pole.
2. State whether the following statements are True (T) or False (F). (ii) Similar poles of a magnet repel each other. [ ]
True. Like poles, that is North-North or South-South, repel each other, while unlike poles attract.
2. State whether the following statements are True (T) or False (F). (iii) Iron filings mostly stick in the middle of a bar magnet when it is brought near them. [ ]
False. Iron filings stick most near the two ends or poles of the bar magnet where the magnetic attraction is strongest, and very few stick in the middle.
2. State whether the following statements are True (T) or False (F). (iv) A freely suspended bar magnet always aligns with the north-south direction. [ ]
True. A freely suspended magnet comes to rest along the north-south direction, with its North pole pointing towards geographic north.
3. Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting interaction between them for different situations. Fill in the blanks. N – N
Repulsion. Two North poles are like poles and repel each other.
3. Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting interaction between them for different situations. Fill in the blanks. N – S
Attraction. North and South are unlike poles and attract each other.
3. Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting interaction between them for different situations. Fill in the blanks. S – N
Attraction. South and North are unlike poles and attract each other.
3. Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting interaction between them for different situations. Fill in the blanks. S – S
Repulsion. Two South poles are like poles and repel each other.
4. Atharv performed an experiment in which he took a bar magnet and rolled it over a heap of steel U-clips (Fig. 4.15). According to you, which of the options given in Table 4.3 is likely to be his observation? Position A Position B Position C (i) 10 2 10 (ii) 10 10 2 (iii) 2 10 10 (iv) 10 10 10 Table 4.3: Number of pins attracted by the magnet at its various positions
Option (i) 10 at Position A, 2 at Position B and 10 at Position C. The ends A and C of the bar magnet are its poles where magnetic strength is maximum, so they pick up many clips, while the middle B has weak magnetism and picks up very few.
5. Reshma bought three identical metal bars from the market. Out of these bars, two were magnets and one was just a piece of iron. How will she identify which two amongst the three could be magnets (without using any other material)?
Label the bars 1, 2 and 3. Bring them in pairs close to each other without touching. If two bars repel each other, both must be magnets because only magnets show repulsion and iron is only attracted. Iron is attracted to both magnets but never repels any bar. So test: if 1 repels 2, then 1 and 2 are the magnets and 3 is the iron. If 1 attracts 2, try 1 with 3 and 2 with 3. The pair that repels identifies the two magnets. Attraction alone is not conclusive because a magnet attracts both iron and the opposite pole of another magnet.
6. You are given a magnet which does not have the poles marked. How can you find its poles with the help of another magnet which has its poles marked?
Bring the marked North pole of the known magnet near one end of the unmarked magnet. If that end is repelled, it is also a North pole, because like poles repel. If it is attracted, it is a South pole. Check the other end to confirm the opposite polarity. The end attracted to the known North is South and the end repelled is North.
7. A bar magnet has no markings to indicate its poles. How would you find out near which end its North pole is located without using another magnet?
Suspend the magnet freely with a thread tied at its centre so it hangs horizontally, or float it on a cork in water. Allow it to come to rest. It will align in the north-south direction. The end pointing towards geographic north is the North pole of the magnet and the end pointing towards geographic south is its South pole. A magnetic compass can also be used in the same way - the end of the bar that attracts the south-pointing end of the compass needle is its North pole.
8. If the earth is itself a magnet, can you guess the poles of earth’s magnet by looking at the direction of the magnetic compass?
Yes. The north-pointing end of a compass needle is its North pole. It points towards Earth's geographic north because it is attracted to Earth's magnetic south pole located near geographic north. Similarly, the south-pointing end of the needle points towards Earth's magnetic north pole located near geographic south. So Earth's magnetic south is near geographic north and Earth's magnetic north is near geographic south.
9. While a mechanic was repairing a gadget using a screw driver, the steel screws kept falling down. Suggest a way to solve the problem of the mechanic on the basis of what you have learnt in this chapter.
Magnetise the tip of the steel screwdriver by rubbing it repeatedly in one direction with one pole of a bar magnet. The tip will become a temporary magnet and attract the small steel screws, holding them to the tip and preventing them from falling until they are fixed.
10. Two ring magnets X and Y are arranged as shown in Fig. 4.16. It is observed that the magnet X does not move down further. What could be the possible reason? Suggest a way to bring the magnet X in contact with magnet Y, without pushing either of the magnets.
Magnet X levitates because like poles of X and Y are facing each other, so they repel and the repulsive force balances the weight of X. To bring them into contact, flip one of the ring magnets over so that unlike poles face each other. Then they will attract and come together. Alternatively, keep them far apart, rotate one by 180 degrees and bring them near again.
11. Three magnets are arranged on a table in the form of the shape shown in Fig. 4.17. What is the polarity, N or S, at the ends 1, 2, 3, 4 and 6 of the magnets? Polarity of one end (5) is given for you.
End 5 is given as N, so the other end of that same magnet, end 6, must be S. Magnets placed close to each other arrange with opposite poles together due to attraction. Therefore end 4 near end 5 must be S, so the opposite end 3 of that middle magnet is N. End 2 near end 3 must be S, so the opposite end 1 is N. Hence 1 is N, 2 is S, 3 is N, 4 is S, 6 is S. All adjacent facing ends are opposite polarities.