Olympiad – Class X – Science - Phy - Magnetic Effects of Electric Current

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Question - 1

If the index finger points towards the north and the middle finger towards the east while using Fleming's left-hand rule, what will be the direction of the force acting on the conductor?

  • A South
  • B West
  • C Upward
  • D Downward

Question - 2

What is the most appropriate reason for the popularity of AC over DC?

  • A AC is not continuous.
  • B DC cannot be generated.
  • C There is very little loss of energy in AC transmission.
  • D There is very little gain of energy in AC transmission.

Question - 3

A current that always flows in the same direction through an electrical device is called

  • A a direct current.
  • B an alternating current.
  • C a varying current.
  • D a magnetic current.

Question - 4

The direction of magnetic field at any point can be found by using

  • A a current carrying wire.
  • B a compass needle.
  • C a scale and a ruler.
  • D a bar magnet.

Question - 5

When a small magnetic needle is placed below a horizontal conductor carrying a strong current from west to east, its north pole will point in the direction of

  • A west - east.
  • B south - west.
  • C north - south.
  • D east - west.

Question - 6

A commutator changes the direction of current in the coil of

  • A a DC motor.
  • B a DC motor and an AC generator.
  • C a DC generator.
  • D an AC generator.

Question - 7

Fleming's left hand rule is used in finding the direction of the magnetic field around a

  • A circular loop.
  • B moving coil.
  • C straight conductor.
  • D magnetic loop.

Question - 8

A current carrying wire in a magnetic field results in 

  • A an electric force
  • B magnetic induction.
  • C a motor effect.
  • D None of the above.

Question - 9

A magnet is inserted into the centre of a coil and an e.m.f. is induced across the coil. The magnitude of the induced current depends on

  • A the diameter of the coil.
  • B the strength of a magnet.
  • C the thickness of the wire with which the coil is made.
  • D All of the above.

Question - 10

In a circular coil, the current is found to be flowing in anticlockwise direction. In which direction is the magnetic field produced at a point on the axis of the coil?

  • A It is parallel to the plane of the coil.
  • B It is perpendicular to the plane of the coil.
  • C It is above the plane of the coil.
  • D It is below the plane of the coil.