Magnetic Effects of Electric Current

MAGNETIC EFFECTS OF ELECTRIC CURRENT

SHORT ANSWER TYPE QUESTIONS (SAQ)

1. Answer the following questions : (i) Define electromagnetic induction. (ii) What is a permanent magnet? Give one use...

2. Why are fuses fitted in the fuse box of a domestic electricity supply? Answer : Fuses are placed in the fuse box...

3. Why does a compass needle get deflected when brought near a bar magnet? Answer : When you hold a compass close t...

4. Answer the following questions: (i) Name and state the rule to determine the polarity of the two faces of a current c...

5. Why don't two magnetic lines of force intersect each other? Answer : When you draw a line touching a point on a...

6. An electric switch should not be touched with wet hands while putting it on or off. Give a reason for your answer....

7. Define alternating current and direct current. Explain why alternating current is preferred over direct current for t...

8. Mention and explain the function of an earth wire. Why it is necessary to earth metallic appliances? Answer : M...

9. A compass needle is placed near a current carrying straight conductor. State your observation for the following cases...

10. Why does a magnetic needle show a deflection when brought close to a current carrying conductor? Answer : When...

11. Answer the following question: (i) What type of magnetic field is produced due to a straight current carrying conduc...

12. Explain why, it is more dangerous to touch the live wire of a mains supply rather than the neutral wire. Answer...

14. (a) State Right Hand Thumb rule to find the direction of the magnetic field around a current carrying straight condu...

15. Answer the following questions: (i) What do you mean by Overloading? (ii) Define an electromagnet. (iii) What is a g...

16. Give reason for the following : (i) There is either a convergence or a divergence of magnetic field lines near the...

17. A magnetic compass needle is placed in theplane of paper near point A, as shown in the figure. In which plane should...

18. Why steel is not used for making electromagnets? Answer : Steel doesn't lose all its magnetism when the electri...

19. Meena draws magnetic field lines of a field close tothe axis of a current carrying circular Loop. As she moves away...

20. Answer the following questions: (i) What is the principle of an electric motor? (ii) What is the role of a split rin...

21. Why does it become more difficult to move a magnet towards a coil when the number of turns in a coil have been incre...

22. Under what conditions is permanent electromagnet obtained if a current carrying solenoid is used? Support your answe...

23. Answer the following questions: (i) State Ampere's swimming rule. (ii) Name and state the rule to determine the dire...

24. A house has a main fuse of 5 A rating. What is the maximum number of 40 W tube lights which can be used at a 220...

25. State the condition in each case of the magnitude of force on a current carrying conductor placed in a magnetic fiel...

26. What does the direction of thumb indicate in the right-hand thumb rule? In what way is this rule different from Flem...

27. Name some devices in which electric motors are used. Answer : Electric motors are found in devices like fans,...

28. List three sources of magnetic fields. Answer : There are three ways to make magnetic fields: i. Using permane...

29. State Fleming's right hand rule. Answer : It says, "Extend your right hand so that your index finger, middle fi...

30. Explain why, an electromagnet is called a temporary magnet? Answer : An electromagnet is known as a temporary m...

31. How will you decide whether the magnetic field at a point is due to some current carrying conductor or due to earth?...

32. Why is the fuse wire fitted in a porcelain casing? Answer : Fuse wire is placed inside a porcelain casing becau...

33. What are the factors affecting the strength of an electromagnet? Answer : Factors affecting the strength of an...

34. How is the type of current that we receive in domestic circuit different from the one that runs a clock? Answe...

35. When does an electric short circuit occur? Answer : When the live and neutral wires touch, the resistance in...

36. A house has a main fuse of 5 A rating, 3 bulbs each of 100 W and 8 tube lights each of 40 W are used simultaneously...

37. (i) Alternating current has a frequency of 50 Hz. What is meant by this statement? How many times does it change its...

38. Name four appliances where in an electric motor (a rotating device that converts electrical energy to mechanical ene...

39. What is the role ofa fuse used in series with any electrical appliance? Why should a fuse with a defined rating not...

40. A current carrying conductor is placed in a magnetic field. Now answer the following. (i) List the factors on which...

41. AB is a current carrying conductor in the plane of the paper as shown in figure. What are the directions of magnetic...

42. Two coils A and B are placed close to each other. If the current in coil A is changed, will some current be induced...

43. Give reason for the following (i) There is either a convergence or a divergence of magnetic field lines near the end...

44. Which of the following fuse ratings would be suitable for an electric motor of power 3 kW, if it is operated at 220...

45. What is the function of an earth wire? Why is it necessary to earth metallic appliances? Answer : The earth...

46. When is the force experienced by a current carrying conductor placed in a magnetic field largest? Answer : Th...

47. Answer the following questions: (i) What do you mean by 'magnetic field' of a magnet? (ii) What are magnetic field l...

48. (i) Why is an alternating current (A.C.) considered to be advantageous over direct current (D.C.) for the long dista...

49. List the properties of magnetic lines of force. Answer : Properties of magnetic field lines : i. Magnetic fie...

50. Give reason for the following : The burnt out fuse should be replaced by another fuse of identical rating. Answ...

51. Write one application of Flemings left hand rule. Answer : Fleming's left-hand rule helps determine the direct...

52. What is a solenoid? When does a solenoid behave as a magnet? Answer : A solenoid is a coil made up of many loo...

53. Why is soft iron generally used as the core of the electromagnet? Answer : Soft iron is often used for making e...

54. A magnetic compass shows a deflection, when placed near a current carrying wire. How will the deflection of the comp...

55. It is established that an electric current through a metallic conductor produces a magnetic field around it. Is ther...

56. What does the divergence of magnetic field lines near the ends of a current carrying straight solenoid indicate?...

57. What is the role of the two conducting stationary brushes in a simple electric motor? Answer : The brushes are...

58. What is the difference between a direct current and an alternating current? How many times does the AC used in India...

LONG ANSWER TYPE QUESTIONS (LAQ)

1. Describe the activity that shows that a current-carrying conductor experiences a force perpendicular to its length an...

2. With the help of a labeled circuit diagram, illustrate the pattern of field lines of the magnetic field around a curr...

3. Explain with the help of a labeled diagram the distribution of magnetic field due to a current through a circular loo...

4. Why does a magnetic compass needle pointing north and south in the absence of a nearby magnet get deflected when a ba...

5. Draw a labeled circuit diagram of a simple electric motor and explain its working. In what way are these simple elect...

NCERT SOLUTION

Page 196 1. Why does a compass needle get deflected when brought near a bar magnet? A compass needle is a...

Page 201-202 1. Consider a circular loop of wire lying in the plane of the table. Let the current pass through...

Page 201-202 1. Which of the following property of a proton can change while it moves freely in a magnetic fie...

Page 205 1. Name two safety measures commonly used in electric circuits and appliances....

Page 207 1. Which of the following correctly describes the magnetic field near a long straight wire...