Moving Charges And Magnetism

15 Questions | Total Attempts: 1244

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Moving Charges And Magnetism

Time: 30 Minute


Questions and Answers
  • 1. 
    A wire is placed parallel to the lines of force in mangnetic field and current flows in the wire. Then
    • A. 

      The wire will experience a torque

    • B. 

      The wire will experience a force along the direction of magnetic field

    • C. 

      The wire will not experience any force

    • D. 

      The wire will experience a perpendicular force.

  • 2. 
    A circular coil of radius 4 cm and 20 turns carries a current of 3A. It is placed in a magnetic field of induction 0.5T. The magnetic dipole moment of the coil is
    • A. 

      0.6Am2

    • B. 

      0.45 Am2

    • C. 

      0.3 Am2

    • D. 

      0.15 Am2

  • 3. 
    Currents of 10 ampere and 2 ampere are passed through two parallel wires A and B respectively in opposite directions. If the wire A is infinitely long and the length of the wire B is 2m. The force acting on the conductor B, which is situated at 10 cm distance form A will be
    • A. 

      8 X 10–5N

    • B. 

      5 X 10–5N

    • C. 

      8π X 10–7N

    • D. 

      4π X 10–7N

  • 4. 
    To convert a galvanometer into an ammeter, we connect
    • A. 

      Low resistance in series

    • B. 

      Low resistance in parallel

    • C. 

      High resistance in series

    • D. 

      High resistance in parallel

  • 5. 
    Two parallel conductors are carrying current 'i' in the same direction. Force experienced per unit length by each conductor (distance between the conductors is r) would be
    • A. 

      Repulsion and 

    • B. 

      Repulsion and 

    • C. 

      Attraction and 

    • D. 

      Attraction and 

  • 6. 
    If a particle is moving in a uniform magnetic field, then
    • A. 

      Its momentum changes but total energy ramains the same

    • B. 

      Both momentum and total energy remains the same

    • C. 

      Its total energy changes but momentum remains same

    • D. 

      Both momentum and tatal energy will change

  • 7. 
    A particle A has charge + q and a particle B has charge + 4q with each of them having the same mass m. When allowed to fall from rest through the same electric potential difference, the ratio of their speeds u/ uB will therefore:
    • A. 

      2 : 1

    • B. 

      1 : 2

    • C. 

      1 : 4

    • D. 

      4 : 1

  • 8. 
    E, F and G are three current carrying linear conductors. The direction of net magnetic force on F will be
    • A. 

      In the direction of current flowing in F

    • B. 

      In the plane of paper towards left

    • C. 

      In the plane of paper towards right

    • D. 

      Normal to the plane of paper

  • 9. 
    An electron is moving along the positive X-axis. You want to apply a magnetic field for a short times so that the electron may reverse its direction and move parallel to the negative X-axis. This can be done by applying the magnetic field along
    • A. 

      X-axis only

    • B. 

      Y-axis only

    • C. 

      Z-axis only

    • D. 

      Y and Z axes

  • 10. 
    A proton moving with a constant velocity passes through a region of space without change in its velocity. If E and B represent electric and magnetic fields respectively, this region of space may not have
    • A. 

      E ≠ 0, B = 0

    • B. 

      E ≠ 0, B ≠ 0

    • C. 

      E = 0, B ≠ 0

    • D. 

      E = 0, B = 0

  • 11. 
    Two identical magnetic dipoles of magnetic moment 1.0 A m2 each, placed at a separation of 2 m with their axes perpendicular to each other. The resultant magnetic field at a point midway between the dipoles is
    • A. 

      T

    • B. 
    • C. 
    • D. 
  • 12. 
    A galvanometer of resistance 100 Ω gives full scale deflection for 20 mV. Find the resistance to be attached so that it gives full scale deflection of 5V.
    • A. 

      in parallel

    • B. 

      in Series

    • C. 

      in parallel

    • D. 

      in Series

  • 13. 
    When a charged particle enters in a uniform magnetic field, its kinetic energy
    • A. 

      Remains constant

    • B. 

      Increases

    • C. 

      Decreases

    • D. 

      Becomes zero

  • 14. 
    Two insulating rings, one of slightly smaller diameter than the other are suspended along their common diameter as shown. Initially the planes of the rings are mutually perpendicular. When a steady current is set up in each of them
    • A. 

      The two rings rotate into a common plane

    • B. 

      The inner ring oscillates about its initial position

    • C. 

      The inner ring stays stationary while the outer one moves into the plane of the inner ring

    • D. 

      The outer ring stays stationary while the inner one moves into the plane of the outer ring

  • 15. 
    A bar magnet has a magnetic moment , and is placed in a magnetic field of 0.2 T. work done in turning the magnet from parallel to anti parallel position relative to the field direction is
    • A. 

      0.5 J

    • B. 

      1 J

    • C. 

      2.0 J

    • D. 

      Zero

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