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Set 6 of 19 · Questions 151-180 of 549

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JEE Main Physics · Moving Charges & Magnetism · Set 6 (Q151-180)

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  1. 151.
    In a crossed field, the magnetic field induction is and electric field intensity is . At which velocity the electron will travel in a straight line without the effect of electric and magnetic fields?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  2. 152.
    A charge is accelerated through a potential difference . It is then passed normally through a uniform magnetic field, where it moves in a circle of radius . The potential difference required to move it in a circle of radius is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  3. 153.
    A gyromagnetic ratio of the electron revolving in a circular orbit of hydrogen atom is . What is the mass of the electron? Given charge of the electron .
    1. (1)1.1× kg
    2. (2)
    3. (3)
    4. (4)0.1× kg
  4. 154.
    A long solenoid has 70 turns and carries current . An electron moves within the solenoid in a circle of radius perpendicular to the solenoid axis. If the speed of the electron is then the current in the solenoid is(Take SI unit, mass of electron , charge of electron )
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  5. 155.
    A square current carrying loop is suspended in a uniform magnetic field acting in the plane of the loop. If the force on one arm of the loop is . the net force on the remaining three arms of the loop is
    1. (1)
    2. (2)
    3. (3)
    4. (4).
  6. 156.
    A solenoid of length having 100 turns carries a current of . The magnetic field at one end of the solenoid is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  7. 157.
    A solenoid of 1200 turns is wound uniformly in a single layer on a glass tube 2 m long and 0.2 m in diameter. The magnetic intensity at the center of the solenoid when a current of 2 A flows through it is:
    1. (1)2.4 x
    2. (2)1.2 x
    3. (3)1 A
    4. (4)2.4 x
  8. 158.
    A current carrying coil is subjected to a uniform magnetic field. The coil will orient so that its plane becomes
    1. (1)inclined at to the magnetic field
    2. (2)inclined at any arbitrary angle to the magnetic field
    3. (3)parallel to the magnetic field
    4. (4)perpendicular to magnetic field.
  9. 159.
    Consider a tightly wound 100 turn coil of radius carrying a current of . The magnitude of the magnetic field at the centre of the coil is
    1. (1)
    2. (2)
    3. (3)
    4. (4)0
  10. 160.
    A magnetic needle suspended parallel to a magnetic field requires J of work to turn it through 60°. The torque needed to maintain the needle in this position will be:
    1. (1)
    2. (2)3J
    3. (3)
    4. (4)
  11. 161.
    Magnetic field at a distance from an infinitely long straight conductor carrying a steady current varies as
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  12. 162.
    The work done in turning a magnet of magnetic moment by an angle of from the meridian, is times the corresponding work done to turn it through an angle of . The value of is given by
    1. (1)1/2
    2. (2)1/4
    3. (3)2
    4. (4)1
  13. 163.
    A proton carrying 1 kinetic energy is moving in a circular path of radius in uniform magnetic field. What should be the energy of an ‐particle to describe a circle of same radius in the same field?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  14. 164.
    A strong magnetic field is applied on a stationary electron. Then the electron
    1. (1)moves in the direction of the field.
    2. (2)moves in an opposite direction of the field.
    3. (3)remains stationary.
    4. (4)starts spinning.
  15. 165.
    A long straight wire carries a current of 18A. The magnitude of the magnetic field at a point from it is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  16. 166.
    A proton moving with a velocity , enters a magnetic field of intensity making an angle with the magnetic field. The force on the proton is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  17. 167.
    An electron is constrained to move along the -axis with a speed of ( is the speed of light) in the presence of electromagnetic wave, whose electric field is The maximum magnetic force experienced by the electron will be (given and electron charge
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  18. 168.
    Two particles and having equal charges are being accelerated through the same potential difference. Thereafter they enter normally in a region of uniform magnetic field and describes circular paths of radii and respectively. The mass ratio of and is:
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  19. 169.
    Proton, Deuteron and alpha particle of same kinetic energy are moving in circular trajectories in a constant magnetic field. The radii of proton, deuteron and alpha particle are respectively and . Which one of the following relation is correct?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  20. 170.
    Assertion (A): When proton and a neutron enter into a transverse magnetic field with equal speeds, then they trace a circular paths of equal radii.
    Reason (R): In a transverse magnetic field the period of revolution of a charged particle in a circular path is directly proportional to the mass of the particle.
    1. (1)Both (A) and (R) are correct and (R) is the correct explanation of .
    2. (2)Both (A) and (R) are correct but (R) is not the correct explanation of .
    3. (3)
    4. (4)
  21. 171.
    A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the center of the loop is It is then bent into a circular coil of turns. The magnetic field at the centre of this coil of turns will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)2.
  22. 172.
    A loop of flexible wire of irregular shape carrying current is placed in an external magnetic field. Identify the effect of the field on the wire.
    1. (1)Loop assumes circular shape with its plane normal to the field.
    2. (2)Loop assumes circular shape with its plane parallel to the field.
    3. (3)Wire gets stretched to become straight.
    4. (4)Shape of the loop remains unchanged.
  23. 173.
    A circular coil of radius and 100 turns carries a current . What is the magnetic moment of the coil ?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  24. 174.
    Two circular coils and are made of two identical wires of the same length. The number of turns in the and are 4 and 2, respectively. The magnetic inductions at the centre of and are and , respectively. The ratio is
    1. (1)0.25
    2. (2)4
    3. (3)0.5
    4. (4)2
  25. 175.
    Choose the wrong statement to complete: An ideal solenoid has
    1. (1)the turns widely separated.
    2. (2)the turns closely wound.
    3. (3)the length is very much greater than the radius.
    4. (4)the magnetic field inside almost uniform.
  26. 176.
    A wire loop of irregular shape carrying current is placed in an external magnetic field. If the wire is flexible, the shape of the loop changes to
    1. (1)helical
    2. (2)circular
    3. (3)straight line
    4. (4)parabolic
  27. 177.
    Two to roads 1 and 2 have total number of turns 200 and 100 respectively with average radii 40 cm and 20 cm respectively. If they carry same current , the radio of the magnetic fields along the two loops is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  28. 178.
    The magnetic dipole moment of a current loop is independent of
    1. (1)magnetic field in which it is lying
    2. (2)number of turns
    3. (3)area of the loop
    4. (4)current in the loop.
  29. 179.
    A singly ionized magnesium atom (A = 24) ion is accelerated to kinetic energy 5 keV and is projected perpendicularly into a magnetic field B of the magnitude 0.5 T. The radius of path formed will be______cm.
  30. 180.
    The magnetic field inside a 200 turns solenoid of radius 10 cm is sla . If the solenoid carries a current of 0.29 A, then the length of the solenoid is .