Question 1

Fill in the blanks

(i) Unlike poles of two magnets — each other, whereas like poles — each other.
(ii) The materials that are attracted towards a magnet are called —
(iii) The needle of a magnetic compass rests along the — direction.
(iv) A magnet always has — poles.

Accepted Answer

(i) Unlike poles of two magnets attract each other, whereas like poles repel each other.
(ii) The materials that are attracted towards a magnet are called magnetic materials.
(iii) The needle of a magnetic compass rests along the north-south direction.
(iv) A magnet always has two poles. — The poles of a magnet always exist in pairs: North and South. Unlike poles attract each other, while like poles repel. Magnetic materials are those attracted by magnets. A freely suspended magnet aligns itself along the north-south direction, which is the direction the compass needle points.

Question 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. [ ]
(ii) Similar poles of a magnet repel each other. [ ]
(iii) Iron filings mostly stick in the middle of a bar magnet when it is brought near them. [ ]
(iv) A freely suspended bar magnet always aligns with the north-south direction. [ ]

Accepted Answer

(i) False. When a magnet is broken, each piece still has both North and South poles; single poles do not exist.
(ii) True. Similar poles repel each other.
(iii) False. Iron filings mostly stick near the poles of a bar magnet, not in the middle.
(iv) True. A freely suspended bar magnet aligns along the north-south direction. — Magnets always have two poles; breaking them does not produce single poles. Like poles repel, unlike poles attract. Iron filings gather near poles where magnetic force is strongest. A suspended magnet aligns with Earth's magnetic field, pointing north-south.

Question 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.

|  Column I | Column II  |
| --- | --- |
|  N – N | ---  |
|  N – --- | Attraction  |
|  S – N | ---  |
|  --- – S | Repulsion  |

Accepted Answer

|  Column I | Column II  |
| --- | --- |
|  N – N | Repulsion  |
|  N – S | Attraction  |
|  S – N | Attraction  |
|  S – S | Repulsion  | — Like poles repel each other (N-N and S-S), and unlike poles attract each other (N-S and S-N). Therefore, the blanks correspond to repulsion for N-N and attraction for S-N.

Question 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?

Table 4.3: Number of pins attracted by the magnet at its various positions

|   | Position A | Position B | Position C  |
| --- | --- | --- | --- |
|  (i) | 10 | 2 | 10  |
|  (ii) | 10 | 10 | 2  |
|  (iii) | 2 | 10 | 10  |
|  (iv) | 10 | 10 | 10  |

Accepted Answer

Option (i) is likely correct: 10 pins at Position A, 2 pins at Position B, and 10 pins at Position C.

Explanation: The ends of the bar magnet (Positions A and C) are poles and attract more steel U-clips, while the middle (Position B) is weaker magnetically and attracts fewer clips. — The poles of a bar magnet are at the ends, where the magnetic force is strongest, attracting more steel U-clips. The middle part has weaker magnetic force, attracting fewer clips. Hence, the number of clips attracted is highest at positions A and C and lowest at B.

Question 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)?

Accepted Answer

Reshma can bring the bars close to each other and observe their interactions. The two magnets will repel or attract each other depending on their poles, while the piece of iron will only be attracted and will not repel any bar. Alternatively, she can suspend each bar freely; the magnets will align along the north-south direction, while the iron piece will not show this behavior. — Magnets have poles and can attract or repel other magnets, while iron is only attracted. By observing attraction and repulsion between the bars, Reshma can identify the magnets. Also, a freely suspended magnet aligns north-south, unlike iron.

Question 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?

Accepted Answer

Bring the unmarked magnet close to the marked magnet. The end of the unmarked magnet that attracts the North pole of the marked magnet is its South pole, and the end that repels the North pole is its North pole. Similarly, using attraction and repulsion between known poles, the poles of the unmarked magnet can be identified. — Like poles repel and unlike poles attract. By bringing the known North pole close to each end of the unknown magnet, the end that attracts is South pole and the one that repels is North pole.

Question 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?

Accepted Answer

Suspend the bar magnet freely using a thread so that it can rotate. The magnet will come to rest aligning itself along the north-south direction. The end which points towards the geographic north is the North pole of the magnet. — A freely suspended magnet aligns with Earth's magnetic field. The end pointing north is the magnet's North pole, and the opposite end is the South pole.

Question 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?

Accepted Answer

The magnetic compass needle points towards the geographic north, which means the Earth's geographic north corresponds to the magnetic South pole (since opposite poles attract). Therefore, Earth's magnetic North pole is near the geographic South Pole, and Earth's magnetic South pole is near the geographic North Pole. — Since the compass needle's North pole points north, it is attracted by Earth's magnetic South pole located near the geographic North Pole. Hence, Earth's magnetic poles are opposite to the geographic poles.

Question 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.

Accepted Answer

The mechanic can magnetize the screwdriver by rubbing a magnet along its length in one direction several times. This will magnetize the screwdriver tip and help hold the steel screws in place, preventing them from falling. — Magnetizing the screwdriver tip creates a magnetic force that attracts and holds the steel screws, making it easier to handle them during repair.

Question 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.

Accepted Answer

The magnet X does not move down further because like poles of magnets X and Y are facing each other, causing repulsion. To bring magnet X in contact with magnet Y without pushing, rotate one magnet so that unlike poles face each other, allowing attraction and contact. — Like poles repel, preventing movement. By rotating one magnet to align opposite poles, the magnets will attract and come into contact without forceful pushing.

Question 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.

Accepted Answer

Since end 5 is given (assumed known), the polarity of adjacent ends can be deduced by the rule that opposite poles attract and like poles repel. By following the arrangement and applying this rule, the polarities at ends 1, 2, 3, 4, and 6 can be determined accordingly. — Using the known polarity at end 5 and the arrangement of magnets, the poles at other ends are assigned so that adjacent ends attract (opposite poles) and non-adjacent ends repel (like poles). This logical deduction helps identify the polarities.

Question 12

Which of the following materials is attracted by a magnet?

Accepted Answer

Iron — Magnetic materials are those that are attracted by a magnet. Iron is a magnetic material, whereas plastic, wood, and glass are non-magnetic and do not get attracted to magnets.

Question 13

What are the two poles of a magnet called?

Accepted Answer

The two poles of a magnet are called the North pole and the South pole. — A magnet has two ends called poles. One end is the North pole and the other end is the South pole. These poles are responsible for the magnetic forces and always exist in pairs.

Question 14

Why do iron filings stick more at the ends of a bar magnet than in the middle?

Accepted Answer

Iron filings stick more at the ends of a bar magnet because the magnetic force is strongest at the poles. The ends are called the North and South poles where the magnetic field is concentrated. — When iron filings are spread near a bar magnet, they arrange themselves along the magnetic field lines. The magnetic force is strongest at the poles (ends) of the magnet, so more filings stick there compared to the middle part where the magnetic force is weaker.

Question 15

What happens when a bar magnet is freely suspended by a thread and allowed to rest?

Accepted Answer

When a bar magnet is freely suspended by a thread, it comes to rest in the north-south direction. This happens because the Earth acts like a giant magnet and the magnet aligns itself with Earth's magnetic field. — The freely suspended magnet aligns itself along the Earth's magnetic field lines. The end that points towards the geographic north is called the North-seeking pole. This property helps in finding directions using a magnetic compass.

Exploring Magnets

Exploring Magnets — Study Notes

Exploring Magnets

Magnetic and Non-magnetic Materials

Poles of Magnet

Practice Questions — Exploring Magnets

All 12 Chapters in Curiosity