Class 10 Chapter 2 Magnetic Effect of Electric Current Physics Solution S.Chand. Part 1

 Part 1 Page 73

Very Short Answer Type Questions

1. State any two properties of magnetic field lines. 

1. Two properties of magnetic field lines are:

   a. They form continuous closed loops, extending from the north pole to the south pole outside a magnet and from the south pole to the north pole inside a magnet.

   b. The density of magnetic field lines indicates the strength of the magnetic field, with denser lines indicating stronger magnetic fields.

2. What are the two ways in which you can trace the magnetic field pattern of a bar magnet ? 

1. The two ways to trace the magnetic field pattern of a bar magnet are:

   a. Sprinkling iron filings around the magnet: Iron filings align themselves along the magnetic field lines, allowing us to visualize the pattern.

   b. Using a magnetic compass: Placing a compass around the magnet will show how the needle aligns with the magnetic field lines, indicating the direction of the field.

3. You are given the magnetic field pattern of a magnet. How will you find out from it where the magnetic field is the strongest ? 

1. To find where the magnetic field is the strongest from the magnetic field pattern of a magnet:

   Look for regions where the magnetic field lines are closest together. The density of field lines is directly proportional to the strength of the magnetic field. Therefore, where the lines are most densely packed, the magnetic field is strongest.

4. State whether the following statement is true or false : The axis of earth’s imaginary magnet and the geographical axis coincide with each other. 

1. False. The axis of the Earth's imaginary magnet (magnetic axis) and the geographical axis do not coincide. The magnetic axis is tilted with respect to the geographical axis. This is why compass needles don't point exactly towards the geographic North Pole, but rather towards the magnetic North Pole.

5. Why does a compass needle get deflected when brought near a bar magnet ? 

1. A compass needle gets deflected when brought near a bar magnet because of the magnetic field produced by the magnet. The needle is itself a small magnet with a north and south pole. When placed near the bar magnet, the magnetic field of the bar magnet exerts a force on the compass needle, causing it to align with the magnetic field lines of the bar magnet.

6. Where do the manufacturers use a magnetic strip in the refrigerator ? Why is this magnetic strip used ?

1. Manufacturers use a magnetic strip in the refrigerator door seal. This magnetic strip is typically made of a flexible rubber material embedded with magnets or magnetic particles. It's used to create a tight seal between the refrigerator door and the main body of the refrigerator. The magnetic attraction ensures that the door remains closed properly, preventing warm air from entering and helping maintain the internal temperature of the refrigerator.

2. 
   
3. 7. Fill in the following blanks with suitable words : (a) Magnetic field lines leave the north pole of a bar magnet and enter at its south pole. (b) The earth’s magnetic field is rather like that of a bar magnet with its magnetic pole in the northern hemisphere.

 Short Answer Type Questions

8. Draw a diagram to show the magnetic field lines around a bar magnet.

9. What is a magnetic field ? How can the direction of magnetic field lines at a place be determined ? 

8. A magnetic field is a region around a magnetic material or a moving electric charge where magnetic forces are experienced. The direction of magnetic field lines at a place can be determined using a small compass needle. The needle aligns itself along the direction of the magnetic field, indicating the field's direction.

10. Explain why, two magnetic field lines do not intersect each other. 

8. Two magnetic field lines do not intersect each other because if they did, it would imply that at the point of intersection, there would be two directions of the magnetic field, which is not possible. Magnetic field lines always represent the direction a magnetic north pole would take if placed in the field. Therefore, intersecting lines would imply contradictory directions.

11. When an electric current is passed through any wire, a magnetic field is produced around it. Then why an electric iron connecting cable does not attract nearby iron objects when electric current is switched on through it ?

8. An electric iron connecting cable does produce a magnetic field when current flows through it. However, the magnetic field produced is usually very weak due to factors like the small current flow, the cable's insulation, and the short distance between the cable and other objects. Hence, the magnetic force exerted on nearby iron objects is negligible and not enough to attract them significantly.

Long Answer Type Question

12. (a) Define magnetic field lines. Describe an activity to draw a magnetic field line outside a bar magnet from one pole to another pole. (b) Explain why, a freely suspended magnet always points in the north-south direction.

12. (a) Define magnetic field lines: Magnetic field lines are imaginary lines used to represent the direction and strength of the magnetic field around a magnet. They form closed loops, emerging from the north pole and entering the south pole of a magnet.

Activity to draw a magnetic field line outside a bar magnet from one pole to another pole:

1. Place a sheet of paper over a bar magnet.
2. Sprinkle iron filings evenly on the paper.
3. Gently tap the paper to allow the iron filings to align with the magnetic field.
4. Observe how the iron filings arrange themselves, forming curved lines extending from one pole to another.
5. Trace these lines with a pencil to represent the magnetic field lines outside the bar magnet.

(b) Explanation of why a freely suspended magnet always points in the north-south direction:

• Earth acts as a giant magnet with its magnetic north pole and south pole.
• A freely suspended magnet aligns itself with the Earth's magnetic field lines.
• This alignment occurs because the magnet's north pole is attracted to the Earth's magnetic south pole, and its south pole is attracted to the Earth's magnetic north pole.
• As a result, the magnet always points in the north-south direction, aligning with the Earth's magnetic field.

Multiple Choice Questions (MCQs)

13. A strong bar magnet is placed vertically above a horizontal wooden board. The magnetic lines of force will be : 

(a) only in horizontal plane around the magnet (b) only in vertical plane around the magnet (c) in horizontal as well as in vertical planes around the magnet (d) in all the planes around the magnet 

14. The magnetic field lines produced by a bar magnet :

 (a) originate from the south pole and end at its north pole (b) originate from the north pole and end at its east pole (c) originate from the north pole and end at its south pole (d) originate from the south pole and end at its west pole 

15. Which of the following is not attracted by a magnet ?

 (a) steel (b) cobalt (c) brass (d) nickel 

16. The magnetic field lines : 

(a) intersect at right angles to one another (b) intersect at an angle of 45° to each other (c) do not cross one another (d) cross at an angle of 60° to one another 

17. The north pole of earth’s magnet is in the : 

(a) geographical south (b) geographical east (c) geographical west (d) geographical north 

18. The axis of earth’s magnetic field is inclined with the geographical axis at an angle of about : 

(a) 5° (b) 15° (c) 25° (d) 35°

19. The shape of the earth’s magnetic field resembles that of an imaginary : 

(a) U-shaped magnet (b) Straight conductor carrying current (c) Current-carrying circular coil (d) Bar magnet 

20. A magnet attracts : 

(a) plastics (b) any metal (c) aluminium (d) iron and steel 

21. A plotting compass is placed near the south pole of a bar magnet. The pointer of plotting compass will : 

(a) point away from the south pole (b) point parallel to the south pole (c) point towards the south pole (d) point at right angles to the south pole 

22. The metallic pointer of a plotting compass gets deflected only when it is placed near a bar magnet because the pointer has : 

(a) electromagnetism (b) permanent magnetism (c) induced magnetism (d) ferromagnetism 

23. Which of the following statements is incorrect regarding magnetic field lines ?

 (a) The direction of magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points. (b) Magnetic field lines are closed curves (c) If magnetic field lines are parallel and equidistant, they represent zero field strength (d) Relative strength of magnetic field is shown by the degree of closeness of the field lines

Questions Based on High Order Thinking Skills (HOTS) 

24. Copy the figure given below which shows a plotting compass and a magnet. Label the N pole of the magnet and draw the field line on which the compass lies.

25. (a) The diagram shows a bar magnet surrounded by four plotting compasses. Copy the diagram and mark in it the direction of the compass needle for each of the cases B, C and D.

(b) Which is the north pole, X or Y ?

(a)

 (b) 

X is the north pole of the bar magnet.

26. The three diagrams in the following figure show the lines of force (field lines) between the poles of two magnets. Identify the poles A, B, C, D, E and F.

A = N ; B = N ; C = S, D = S ; E = N, F = S 

27. The figure given below shows the magnetic field between two magnets :

(i) Copy the diagram and label the other poles of the magnets. (ii) Which is the weaker magnet ?

(i) S—N ; N—S (ii) Magnet 2