JEE Questions for Physics Moving Charges And Magnetism Quiz 7 - MCQExams.com

The dimension of the magnetic field intensity B is
  • [MLT–2A–1]
  • [MT–2A–1]
  • [ML2TA–2]
  • [M2LT–2A–1]
A current of 2 amp. flows in a long, straight wire of radius 2 mm. The intensity of magnetic field on the axis of the wire is

  • Physics-Moving Charges and Magnetism-82754.png
  • 2)
    Physics-Moving Charges and Magnetism-82755.png

  • Physics-Moving Charges and Magnetism-82756.png
  • Zero
The magnetic field at the centre of a circular coil of radius r carrying current I is B1. The field at the centre of another coil of radius 2r carrying same current I is B2. The ratio B1 / B2 is
  • 1/2
  • 1
  • 2
  • 4
What should be the current in a circular coil of radius 5 cm to annul BH = 5 × 10–5 T
  • 0.4 A
  • 4 A
  • 40 A
  • 1 A
An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has a magnitude of

  • Physics-Moving Charges and Magnetism-82759.png
  • 2)
    Physics-Moving Charges and Magnetism-82760.png

  • Physics-Moving Charges and Magnetism-82761.png
  • Zero
A wire carrying current i is shaped as shown. Section AB is a quarter circle of radius r. The magnetic field is directed
Physics-Moving Charges and Magnetism-82763.png
  • At an angle π/4 to the plane of the paper
  • Perpendicular to the plane of the paper and directed in to the paper
  • Along the bisector of the angle ACB towards AB
  • Along the bisector of the angle ACB away from AB
Two long straight wires are set parallel to each other. Each carries a current i in the same direction and the separation between them is 2r. The intensity of the magnetic field midway between them is
Physics-Moving Charges and Magnetism-82764.png

  • Physics-Moving Charges and Magnetism-82765.png
  • 2)
    Physics-Moving Charges and Magnetism-82766.png
  • Zero

  • Physics-Moving Charges and Magnetism-82767.png
A magnetic field can be produced by
  • A moving charge
  • A changing electric field
  • None of these
  • Both of these
For the magnetic field to be maximum due to a small element of current carrying conductor at a point, the angle between the element and the line joining the element to the given point must be
  • 0°
  • 90°
  • 180°
  • 45°
Gauss is unit of which quantity
  • H
  • B
  • Φ
  • I
On connecting a battery to the two corners of a diagonal of a square conductor frame of side a, the magnitude of the magnetic field at the centre will be
  • Zero
  • 2)
    Physics-Moving Charges and Magnetism-82770.png

  • Physics-Moving Charges and Magnetism-82771.png

  • Physics-Moving Charges and Magnetism-82772.png
The ratio of the magnetic field at the centre of a current carrying coil of the radius a and at a distance \'a\' from centre of the coil and perpendicular to the axis of coil is

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  • 2)
    Physics-Moving Charges and Magnetism-82774.png

  • Physics-Moving Charges and Magnetism-82775.png

  • Physics-Moving Charges and Magnetism-82776.png
A part of a long wire carrying a current i is bent into a circle of radius r as shown in figure. The net magnetic field at the centre Oof the circular loop is
Physics-Moving Charges and Magnetism-82778.png

  • Physics-Moving Charges and Magnetism-82779.png
  • 2)
    Physics-Moving Charges and Magnetism-82780.png

  • Physics-Moving Charges and Magnetism-82781.png

  • Physics-Moving Charges and Magnetism-82782.png
\ On flowing current in a conducting wire the magnetic field produces around it.\ It is a law of
  • Lenz
  • Ampere
  • Ohm
  • Maxwell
The magnetic field near a current carrying conductor is given by
  • Coulomb's law
  • Lenz' law
  • Biot-Savart's law
  • Kirchhoff’s law
A current of 10 A is passing through a long wire which has semicircular loop of the radius 20 cm as shown in the figure. Magnetic field produced at the centre of the loop is
Physics-Moving Charges and Magnetism-82784.png
  • 10 πμT
  • 5 πμT
  • 4 πμT
  • 2 πμT
A wire in the form of a circular loop of one turn carrying a current produces a magnetic field B at the centre. If the same wire is looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is
  • 5 B
  • 3 B
  • 2 B
  • 4 B
A current flows in a conductor from east to west. The direction of the magnetic field at a points above the conductor is
  • Towards north
  • Towards south
  • Towards east
  • Towards west
The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 μT. What will be its value at the centre of the loop
  • 250 μT
  • 150 μT
  • 125 μT
  • 75 μT
The magnetic induction at the centre of a current carrying circular of coil radius r, is
  • Directly proportional to r
  • Inversely proportional to r
  • Directly proportional to r2
  • Inversely proportional to r2
Two wires of same length are shaped into a square and a circle. If they carry same current, ratio of the magnetic moment is
  • 2 : π
  • π : 2
  • π : 4
  • 4 : π
The direction of magnetic lines of force produced by passing a direct current in a conductor is given by
  • Lenz's law
  • Fleming's left hand rule
  • Right hand palm rule
  • Maxwell's law
Two concentric coils each of radius equal to 2π cm are placed at right angles to each other 3 ampere and 4 ampere are the currents flowing in each coil respectively. The magnetic induction in weber/m2 at the centre of the coils will be (μ0 = 4 π × 10–7 Wb/A.m)
  • 5 × 10–5
  • 7 × 10–5
  • 12 × 10–5
  • 10–5
Magnetic field at the centre of a circular coil of radius R due to current Iflowing through it is B. The magnetic field at a point along the axis at distance R from the centre is

  • Physics-Moving Charges and Magnetism-82795.png
  • 2)
    Physics-Moving Charges and Magnetism-82796.png

  • Physics-Moving Charges and Magnetism-82797.png

  • Physics-Moving Charges and Magnetism-82798.png
A 2 μC charge moving around a circle with a frequency of 6.25 × 1012 Hz produces a magnetic field 6.28 tesla at the centre of the circle. The radius of the circle is
  • 2.25 m
  • 0.25 m
  • 13.0 m
  • 1.25 m
  • 3.25 m

Physics-Moving Charges and Magnetism-82801.png
  • μ0
  • 3μ0
  • 6μ0
  • 2μ0
  • Zero
The number of lines of force passing through a unit area placed perpendicularly to the magnetic lines of force is termed as
  • Magnetic induction
  • Magnetic flux density
  • Intensity of magnetic field
  • All of the above
A beam of ions with velocity 2 × 105 m/s enters normally into a uniform magnetic field of 4 × 10–2 tesla. If the specific charge of the ion is 5 × 10–7 C/kg, then the radius of the circular path described will be
  • 0.10 m
  • 0.16 m
  • 0.20 m
  • 0.25 m
An electron having mass 9 × 10–31kg, charge 1.6 × 10–19 C and moving with a velocity of 106 m/s enters a region where magnetic field exists. If it describes a circle of radius 0.10 m, the intensity of magnetic field must be
  • 1.8 × 10–4 T
  • 5.6 × 10–5 T
  • 14.4 × 10–5 T
  • 1.3 × 10–6 T
A proton (mass m and charge +e) and an α–particle (mass 4m and charge +2e) are projected with the same kinetic energy at right angles to the uniform magnetic field. Which one of the following statements will be true
  • The α–particle will be bent in a circular path with a small radius that for the proton
  • The radius of the path of the α–particle will be greater than that of the proton
  • The α–particle and the proton will be bent in a circular path with the same radius
  • The α–particle and the proton will go through the field in a straight line
If the direction of the initial velocity of the charged particle is neither along nor perpendicular to that of the magnetic field, then the orbit will be
  • A straight line
  • An ellipse
  • A circle
  • A helix
The figure shows certain wire segments joined together to form a coplanar loop. The loop is placed in a perpendicular magnetic field in the direction going into the plane of the figure. The magnitude of the field increases with time. I1 and I2 are the currents in the segments ab and cd. Then,
Physics-Moving Charges and Magnetism-82807.png
  • I1> I2
  • I1< I2
  • I1is in the direction ba and I2 is in the direction cd
  • I1 is in the direction ab and I2 is in the direction dc

Physics-Moving Charges and Magnetism-82809.png
  • Always zero
  • Never zero

  • Physics-Moving Charges and Magnetism-82810.png

  • Physics-Moving Charges and Magnetism-82811.png
A proton of mass m and charge +e is moving in a circular orbit in a magnetic field with energy 1 MeV. What should be the energy of α–particle (mass = 4m and charge = +2e), so that it can revolve in the path of same radius
  • 1 MeV
  • 4 MeV
  • 2 MeV
  • 0.5 MeV

Physics-Moving Charges and Magnetism-82814.png
  • No change
  • Reduces to r/2
  • Increases to 2r
  • Stops moving
A proton and an α–particle enter a uniform magnetic field perpendicularly with the same speed. If proton takes 25 μ sec to make 5 revolutions, then the periodic time for the α–particle would be
  • 50 μ sec
  • 25 μ sec
  • 10 μ sec
  • 5 μ sec
A proton (mass = 1.67 × 10–27kg and charge = 1.6 × 10–19 C) enters perpendicular to a magnetic field of intensity 2 weber/m2 with a velocity 3.4 × 107m/sec. The acceleration of the proton should be
  • 6.5 × 1015 m/sec2
  • 6.5 × 1013 m/sec2
  • 6.5 × 1011 m/sec2
  • 6.5 × 109 m/sec2
A charged particle is moving in a circular orbit of radius 6 cm with a uniform speed of 3 × 106 m/s under the action of a uniform magnetic field 2 × 10–4 wb/m2 at right angles to the plane of the orbit. The charge to mass ratio of the particle is
  • 5 × 109 C/kg
  • 2.5 × 1011 C/kg
  • 5 × 1011 C/kg
  • 5 × 1012 C/kg
A uniform magnetic field acts at right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of radius 2 cm. If the speed of the electrons is doubled, then the radius of the circular path will be
  • 2.0 cm
  • 0.5 cm
  • 4.0 cm
  • 1.0 cm

Physics-Moving Charges and Magnetism-82820.png
  • 25 keV
  • 50 keV
  • 200 keV
  • 100 keV
A current I flowing through the loop as shown in figure. The magnetic field at centre O is
Physics-Moving Charges and Magnetism-82822.png

  • Physics-Moving Charges and Magnetism-82823.png
  • 2)
    Physics-Moving Charges and Magnetism-82824.png

  • Physics-Moving Charges and Magnetism-82825.png

  • Physics-Moving Charges and Magnetism-82826.png

Physics-Moving Charges and Magnetism-82828.png

  • Physics-Moving Charges and Magnetism-82829.png
  • 2)
    Physics-Moving Charges and Magnetism-82830.png

  • Physics-Moving Charges and Magnetism-82831.png

  • Physics-Moving Charges and Magnetism-82832.png
The magnetic force on a charged particle moving in the field does not work, because
  • Kinetic energy of the charged particle does not change
  • The charge of the particle remains same
  • The magnetic force is parallel to velocity of the particle
  • The magnetic force is parallel to magnetic field

Physics-Moving Charges and Magnetism-82835.png

  • Physics-Moving Charges and Magnetism-82836.png
  • 2)
    Physics-Moving Charges and Magnetism-82837.png

  • Physics-Moving Charges and Magnetism-82838.png

  • Physics-Moving Charges and Magnetism-82839.png
Which of the following statements is true
  • The presence of a large magnetic flux through a coil maintains a current in the coil if the circuit is continuous
  • A coil of a metal wire kept stationary in a non-uniform magnetic field has an e.m.f. induced in it
  • A charged particle enters a region of uniform magnetic field at an angle of 85° to the magnetic lines of force; the path of the particle is a circle
  • There is no change in the energy of a charged particle moving in a magnetic field although a magnetic force is acting on it
An electron and a proton enter region of uniform magnetic field in a direction at right angles to the field with the same kinetic energy. They describe circular paths of radius re and rp respectively. Then
  • re = rp
  • re< rp
  • re> rp
  • re may be less than or greater than rp depending on the direction of the magnetic field
A proton of mass 1.67 × 10–27 kg and charge 1.6 × 10–19C is projected with a speed of 2 × 106 m/s at an angle of 60° to the X–axis. If a uniform magnetic field of 0.104 tesla is applied along Y-axis, the path of the proton is
  • A circle of radius = 0.2 m and time period π × 10–7s
  • A circle of radius = 0.1 m and time period 2π × 10–7s
  • A helix of radius = 0.1 m and time period 2π × 10–7s
  • A helix of radius = 0.2 m and time period 4π × 10–7s
A proton and a deutron both having the same kinetic energy, enter perpendicular into a uniform magnetic field B. For motion of proton and deutron on circular path of radius Rp and Rd respectively, the correct statement is

  • Physics-Moving Charges and Magnetism-82843.png
  • 2)
    Physics-Moving Charges and Magnetism-82844.png

  • Physics-Moving Charges and Magnetism-82845.png

  • Physics-Moving Charges and Magnetism-82846.png
A proton and an electron both moving with the same velocity v enter into a region of magnetic field directed perpendicular to the velocity of the particles. They will now move in circular orbits such that
  • Their time periods will be same
  • The time period for proton will be higher
  • The time period for electron will be higher
  • Their orbital radii will be same
A charge +Q is moving upwards vertically. It enters a magnetic field directed to the north. The force on the charge will be towards
  • North
  • South
  • East
  • West
0:0:1


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