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Question Bank - Magnetic effects of electric current

1.    Why does a compass needle got deflected when brought near a bar magnet?

2.    Draw magnetic field lines of a bar magnet.

3.    List any two properties of magnetic field lines.

4.    The magnetic field in a given region is uniform. Draw a diagram to represent it.

5.    Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right hand rule to find out the direction of magnetic field inside and outside the loop.

6.    Why don’t two magnetic field lines intersect each other?

7.    Explain different ways to induce current in a coil.

8.    State Fleming’s left hand rule.

9.     What is the principle of electric motor?

10.   State the principle of electric generator.

11.   State Fleming’s right hand rule.

12.   State right hand thumb rule.

13.   Name some sources of direct current.

14.   Which sources produces alternating current?

15.   Name two safety measures commonly used in electric circuit and appliances.

16.   What precautions should be taken to avoid the overloading of domestic electric circuit?

17.   An electric oven of a 2kW power rating is operated in a domestic circuit (220 V) that has a current rating of 5A. What result do you expect? Explain.

18.   Define electromagnetic induction.

19.   List three sources of magnetic field.

20.   How does a solenoid behaves like a bar magnet? Can you determine the north and south poles of a current carrying solenoid with the help of a bar magnet? Explain.

21.   When is the force experienced by a current-carrying conductor placed in a magnetic field largest?

22.   Imagine you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of the magnetic field?

23.   A coil of insulated copper wire is connected to a galvanometer. What would happen if a bar magnet is

  (i) Pushed into the coil.

  (ii) Withdrawn from inside the coil.

  (iii) Held stationary inside the coil.

24.   Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.

25.   State the rule to determine the direction of a

  (i) Magnetic field produced around a straight conductor carrying current.

  (ii) Force experienced by a current carrying straight conductor placed in a magnetic field which is perpendicular to it.

  (iii) Current induced in a coil due to its rotation in a magnetic field.

26.   When does an electric short-circuit occur?

27.   What is the function of an earth wire? Why is it necessary to earth metallic appliances?

28.   What is the effect of inserting a soft iron core inside a current-carrying solenoid? What is this arrangement known as?

29.   What is the capacity of an electric fuse used in (i)lighting circuit (ii) power circuit used in household supply?

30.   State two characteristics of electric fuse wire.

31.   State two ways by which the strength of an electromagnet can be increased.

32.   State three factors on which the magnitude of force on a current carrying –conductor placed in a magnetic field depends. Can this force be zero for some position of the conductor?

33.   Draw the magnetic field lines around a straight conductor carrying current.

34.   Draw the magnetic field lines due to a current-carrying circular wire.

35.   What is solenoid? Draw the magnetic field lines due to a current carrying solenoid.

36.   Compare the magnetic field produced by a bar magnet and a solenoid?

37.   What is the difference between a direction current and an alternating current? How many times does AC used in India change direction in one second?

38.   In what way can the magnitude of induced current be increased?

39.   How does AC differ from DC? What are the advantages and disadvantages of AC over DC?

40.   What is earthing? How does it work as a safety measure?

41.   What is the function of earth wire? Why is it necessary to earth the metallic appliances?

42.   What is the role of fuse used in series with any electrical appliance?

43.   Why should a fuse with defined rating not be replaced by one with a larger rating?

44.   How is the direction of magnetic field at a point determined?

45.   What is the direction of magnetic field at the centre of a current-carrying circular loop?

46.   A magnetic compass shows a deflection when placed near a current carrying wire. How will the deflection of the compass get affected if the cyrrent in the wire is increased? Support your answer with reason.

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

48.   An electron enters a uniform magnetic field at right anges to it as shown in the figure. In which direction will this electron move? State the principle applied by you in finding the direction of motion of the electron?

49.   What is an electric fuse? How does it function?

50.   A fuse is rated at 8 A, it means:

   (a) It will not work if current is less than 8 A.

   (b) It has a resistance of 8 ohm.

   (c) It will work only if current is 8 A.

   (d) It will burn if current exceeds 8 A.

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