Chapter 4 Solutions — Exploring Magnets

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1. 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.
2. 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.
3. 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. Fill in the blanks. Column I: N–N, N–?, S–N, ?–S. Column II: (blank), Attraction, (blank), Repulsion.
4. 4.
   Atharv rolled a bar magnet over a heap of steel U-clips (Fig. 4.15). The positions A, B, and C are along the magnet. Which option from Table 4.3 (number of pins at each position) is likely to be his observation? Options:

   • (i) A=10, B=2, C=10;
   • (ii) A=10, B=10, C=2;
   • (iii) A=2, B=10, C=10;
   • (iv) A=10, B=10, C=10.
5. 5.
   Reshma bought three identical metal bars. Two are magnets and one is just a piece of iron. How will she identify which two are magnets (without using any other material)?
6. 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?
7. 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?
8. 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?
9. 9.
   While a mechanic was repairing a gadget using a screwdriver, 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.
10. 10.
    Two ring magnets X and Y are arranged as shown in Fig. 4.16. It is observed that magnet X does not move down further. What could be the possible reason? Suggest a way to bring magnet X in contact with magnet Y, without pushing either of the magnets.
11. 11.
    Three magnets are arranged on a table in the form of a shape shown in Fig. 4.17. What is the polarity (N or S) at ends 1, 2, 3, 4, and 6 of the magnets? The polarity of end 5 is given as N.