JEE Questions for Physics Moving Charges And Magnetism Quiz 4 - MCQExams.com

A horizontal overhead powerline is at a height of 4 m from the ground and carries a current of 100 A from East to West. The magnetic field directly below it on the ground is (μ0 = 4π × 10-7 T-mA-1)
  • 5.0 × 10-6, Southward
  • 2.5 × 10-7, Southward
  • 5.0 × 10-6, Northward
  • 2.5 × 10-7, Northward
Two concentric coils of 10 turns each are placed in the same plane. Their radii are 20 cm and 40 cm and carry 0.2 A and 0.3 A current respectively in opposite directions. The magnetic induction (in tesla) at the centre is

  • Physics-Moving Charges and Magnetism-82424.png
  • 2)
    Physics-Moving Charges and Magnetism-82425.png

  • Physics-Moving Charges and Magnetism-82426.png

  • Physics-Moving Charges and Magnetism-82427.png
The strength of the magnetic field around a long straight wire, carrying current, is
  • same everywhere around the wire at any distance
  • inversely proportional to the distance from the wire
  • inversely proportional to the square of the distance from the wire
  • directly proportional to the square of the distance from the wire
The direction of induced magnetic field dB due to current element i dL, at a point of distance r from it, when a current i passes through a long conductor is in the direction
  • of position vector r of the point
  • of current element dL
  • perpendicular to both dL and r
  • perpendicular to dL only
A straight wire of mass 200 g and length 1.5 m carries a current of 2 A. It is suspended in midair by a uniform horizontal magnetic field B. The magnitude of B (in tesla) is
  • 2
  • 1.5
  • 0.55
  • 0.65
A solenoid 1.5 m long and 0.4 cm in diameter possesses 10 turns/cm length. A current of 5 A falls through it. The magnetic field at the axis inside the solenoid is
  • 2π × 10-3 T
  • 2π × 10-5 T
  • 4π × 10-2 T
  • 4π × 10-3 T
A circular coil of 5 turns and of 10 cm mean diameter is connected to a voltage source. If the resistance of the coil is 10 Ω, the voltage of the source so is to nullify the horizontal component of earth's magnetic field of 30 A turn m -1 at the centre of the coil should be
  • 6 V, plane of the coil normal to magnetic meridian
  • 2 V, plane of the coil normal to magnetic meridian
  • 6 V, plane of the coil along the magnetic meridian
  • 2 V, plane of the coil along the magnetic meridian
  • 4 V, plane of the coil normal to magnetic meridian
Which of the following graphs represent variation of magnetic field B with distance r for a straight long wire carrying current ?

  • Physics-Moving Charges and Magnetism-82434.png
  • 2)
    Physics-Moving Charges and Magnetism-82435.png

  • Physics-Moving Charges and Magnetism-82436.png

  • Physics-Moving Charges and Magnetism-82437.png
Two wires A and B are of lengths 40 cm and 30 cm. A is bent into a circle of radius r and B into an arc of radius r. A current i1 is passed through A and i2 through B. To have the same magnetic inductions at the centre, the ratio of i1 : i2 is
  • 3 : 4
  • 3 : 5
  • 2 : 3
  • 4 : 3
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
A long solenoid has 200 turns/cm and carries a current i. The magnetic field at its centre is 6.28 × 10-2 Wb/m2. Another long solenoid has 100 turns/cm and it carries a current i /3. The value of the magnetic field at its centre is
  • 1.05 × 10-2 Wbm-2
  • 1.05 × 10-5 Wbm-2
  • 1.05 × 10-3 Wbm-2
  • 1.05 × 10-4 Wbm-2
An electric current passes through a long straight copper wire. At a distance 5 cm from the straight wire, the magnetic field is B. The magnetic field at 20 cm from the straight wire would be

  • Physics-Moving Charges and Magnetism-82442.png
  • 2)
    Physics-Moving Charges and Magnetism-82443.png

  • Physics-Moving Charges and Magnetism-82444.png

  • Physics-Moving Charges and Magnetism-82445.png
In a hydrogen atom, the electron is making 6.6 × 1015 rps in a circular path of radius 0.53 A°. What is the magnetic induction produced at the centre of orbit?
  • 6.3 T
  • 12.6 T
  • 18.9 T
  • 25.2 T

Physics-Moving Charges and Magnetism-82448.png
  • 1
  • 2
  • 5
  • 6
A long hollow copper tube carries a current I. Then which of the following will be true?
  • The magnetic field B will be zero at all points inside the tube
  • The magnetic field B will be zero only at points on the axis of the tube
  • The magnetic field B will be maximum at points on the axis of the tube
  • The magnetic field will be zero at any point outside the tube
Two concentric coils each of radius equal to 2π cm are placed at right angles to each other. 3 A and 4 A are the currents flowing in each coil respectively. The magnetic induction in Wbm -2 at the centre of the coils will be (10 = 4π × 10-7 WbAm -1)
  • 12 × 10-5
  • 10-5
  • 5 × 10-5
  • 7 × 10-5
A wire shown in figure carries a current of 40 A. If r = 3.14 cm, the magnetic field at point P will be
Physics-Moving Charges and Magnetism-82451.png
  • 1.6 × 10-3 T
  • 3.2 × 10-2 T
  • 4.8 × 10-3 T
  • 6.0 × 10-4 T

Physics-Moving Charges and Magnetism-82453.png
  • 3 : 1
  • 5 : 1
  • 9 : 1
  • 4 : 3
A solenoid of length 1.0 m has a radius of 1 cm and has a total of 1000 turn wound on it. It carries a current of 5 A. If an electron were to move with a speed of 104 ms -1 along the axis of the current carrying solenoid the force experienced by this electron is
  • 2 N
  • 1.2 N
  • zero
  • 2.5 N
Which of the following gives the value of magnetic field according to Biot-Savart\'s law?

  • Physics-Moving Charges and Magnetism-82736.png
  • 2)
    Physics-Moving Charges and Magnetism-82737.png

  • Physics-Moving Charges and Magnetism-82738.png

  • Physics-Moving Charges and Magnetism-82739.png
A proton of mass m and charge q is moving in a plane with kinetic energy E. If there exists a uniform magnetic field B, perpendicular to the plane of the motion, the proton will move in a circular path of radius

  • Physics-Moving Charges and Magnetism-82456.png
  • 2)
    Physics-Moving Charges and Magnetism-82457.png

  • Physics-Moving Charges and Magnetism-82458.png

  • Physics-Moving Charges and Magnetism-82459.png
A stream of electrons and protons are directed towards a narrow slit in a screen (see figure). The intervening region has a uniform electric field E (vertically downwards) and a uniform magnetic field B (out of the plan of the figure) as shown. Then,
Physics-Moving Charges and Magnetism-82461.png

  • Physics-Moving Charges and Magnetism-82462.png
  • 2)
    Physics-Moving Charges and Magnetism-82463.png
  • neither electrons nor protons will go through the slit irrespective of their speed
  • electrons will always be deflected upwards irrespective of their speed

Physics-Moving Charges and Magnetism-82464.png
  • If θ = 0°, the charge moves in a circular path in the x-z plane
  • If θ = 0°, the charge undergoes helical motion with constant pitch along the y-axis
  • If θ = 10°, the charge undergoes helical motion with its pitch increasing with time, along the y-axis
  • If θ = 70°, the charge undergoes linear but accelerated motion along the y-axis
A proton is moving in a uniform magnetic field B in a circular path of radius a in a direction perpendicular to z-axis along which field B exists. Calculate the angular momentum, if the radius a and charge on proton is e.

  • Physics-Moving Charges and Magnetism-82465.png
  • eB2 a
  • a2 eB
  • aeB
An electron having charge 16 × 10 -19 C and mass 9 × 10-31 kg is moving with speed 4 × 10 6 ms -1 in a magnetic field of 2 × 10 -1 Tin a circular orbit. The force acting on electron and the radius of the circular orbit will be
  • 18.8 × 10-13 N, 1.1 × 10-4 m
  • 12.8 × 10-14 N, 1.1 × 10-3 m
  • 12.8 × 10-13 N, 1.1 × 10-3 m
  • 1.28 × 10-13 N, 1.1 × 10-4 m
A proton with energy of 2 MeV enters a uniform magnetic field of 2.5 T normally. The magnetic force on the proton is (take, mass of proton to be 1.6 × 10-27 kg)
  • 3 × 10-12 N
  • 8 × 10-10 N
  • 8 × 10-12 N
  • 2 × 10-10 N
An α-particle with a specific charge of 2.5 × 107 C kg 4 moves with a speed of 2 × 105 ms -1 in a perpendicular magnetic field of 0.05 T. Then, the radius of the circular path described by it is
  • 8 cm
  • 4 cm
  • 16 cm
  • 2 cm
An electron of mass m and charge q is travailing with a speed v along a circular path of radius rat right angles to a uniform of magnetic field B. If speed of the electron is doubled and the magnetic field is halved, then resulting path would have a radius of

  • Physics-Moving Charges and Magnetism-82470.png
  • 2)
    Physics-Moving Charges and Magnetism-82471.png
  • 2r
  • 4r
Two particles of masses ma and mb and same charge are projected in a perpendicular magnetic field. They travel along circular paths of radius ra and rb such that ra > rb . Then which is true?
  • ma va > mb vb
  • ma > mb and va > vb
  • ma = mb and va > vb
  • mb vb > ma va
A proton, a deuteron and an α-particle with the same kinetic energy enter a region of uniform magnetic field moving at right angles to B. What is the ratio of the radii of their circular paths?

  • Physics-Moving Charges and Magnetism-82474.png
  • 2)
    Physics-Moving Charges and Magnetism-82475.png

  • Physics-Moving Charges and Magnetism-82476.png

  • Physics-Moving Charges and Magnetism-82477.png
The proton is energy 1 MeV describes a circular path in plane at right angles to a uniform magnetic field of 6.28 × 10-4 T. The mass of the proton is 17 × 10-27 kg. The cyclotron frequency of the proton is very nearly equal to
  • 107 Hz
  • 105 Hz
  • 106 Hz
  • 104 Hz
An electron beam travels with a velocity of 1.6 × 107 MS -1 perpendicularly to magnetic field of intensity 0.1 T. The radius of the path of the electron beam (me = 9 × 10-31 kg )
  • 9 × 10-5 m
  • 9 × 10-2 m
  • 9 × 10-4 m
  • 9 × 10-3 m
In a magnetic field of 0.05 T area of coil changes from 101cm2 and 100 cm2 without changing the resistance which is 2 Ω . The amount of charge that flow dining this period is
  • 2.5 × 10-6 C
  • 2 × 10-6 C
  • 10-6 C
  • 8 × 10-6 C
A conductor lies along the z–axis at –1.5 ≤ z < 1.5 m and carries a fixed current of 10.0 A in –a z direction (see figure). For a field B = 3.0 × 10-4 e-0.2x ay T, find the power required to move the conductor at constant speed to x = 2.0 m, y = 0 in 5 × 10-3 s. Assume parallel motion along the x – axis.
Physics-Moving Charges and Magnetism-82482.png
  • 1.57 W
  • 2.97 W
  • 14.85 W
  • 29.7 W
A square coil of side 10 cm has 20 turns and carries a current of 12 A. The coil is suspended vertically and the normal to the plane of the coil, makes an angle θ with the direction of a uniform horizontal magnetic field of 0.80 T. If the torque, experienced by the coil, equals 0.96 N-m, the value of θ is
  • 0°
  • 2)
    Physics-Moving Charges and Magnetism-82484.png

  • Physics-Moving Charges and Magnetism-82485.png

  • Physics-Moving Charges and Magnetism-82486.png
If a magnetic dipole of moment M situated in the direction of a magnetic field B is rotated by 180°, then the amount of work done is
  • MB
  • 2MB

  • Physics-Moving Charges and Magnetism-82488.png
  • zero

  • Physics-Moving Charges and Magnetism-82489.png
A straight wire of mass 300 g and length 2.5 m carries a current of 3.5 A. It is suspended in mid air by a uniform horizontal magnetic field B. What is the magnitude of the magnetic field?
  • 0.654 T
  • 0.342 T
  • 1.576 T
  • 0.939 T
A straight wire of mass 200 g and length 1.5 m carries a current of 2 A. It is suspended in mid-air by a uniform horizontal magnetic field B. The magnitude of B (in tesla) is (Assume, g = 9.8 ms -2)
  • 2
  • 1.5
  • 0.55
  • 0.65
An electron moving around the nucleus with an angular momentum 1 has a magnetic moment

  • Physics-Moving Charges and Magnetism-82492.png
  • 2)
    Physics-Moving Charges and Magnetism-82493.png

  • Physics-Moving Charges and Magnetism-82494.png

  • Physics-Moving Charges and Magnetism-82495.png

  • Physics-Moving Charges and Magnetism-82496.png
Two long parallel wires are at a distance 2d apart. They carry steady equal current flowing out of the plane of the paper as shown. The variation of the magnetic field along the line XX' is given by

  • Physics-Moving Charges and Magnetism-82498.png
  • 2)
    Physics-Moving Charges and Magnetism-82499.png

  • Physics-Moving Charges and Magnetism-82500.png

  • Physics-Moving Charges and Magnetism-82501.png
A circular loop and a square loop are formed from the same wire and the same current is passed through them. Find the ratio of their dipole moments.
  • 4π
  • 2)
    Physics-Moving Charges and Magnetism-82503.png

  • Physics-Moving Charges and Magnetism-82504.png
  • 2π
Two thin long parallel wires separated by a distance b are carrying currents of i amp each, the magnitude of the force per unit length exerted by one wire over the other is

  • Physics-Moving Charges and Magnetism-82506.png
  • 2)
    Physics-Moving Charges and Magnetism-82507.png

  • Physics-Moving Charges and Magnetism-82508.png

  • Physics-Moving Charges and Magnetism-82509.png
Two circular concentric loops of radii r1 = 20 cm and r2 = 30 cm are placed in the X- Y plane as shown in the figure. A current I = 7 A is flowing through them. The magnetic moment of this loop system is
Physics-Moving Charges and Magnetism-82511.png

  • Physics-Moving Charges and Magnetism-82512.png
  • 2)
    Physics-Moving Charges and Magnetism-82513.png

  • Physics-Moving Charges and Magnetism-82514.png

  • Physics-Moving Charges and Magnetism-82515.png
A coil of 100 turns and area 2 × 10-2 M2, pivoted about a vertical diameter in a uniform magnetic field carries a current of 5 A. When the coil is held with its plane in North-South direction, it experiences a torque of 0.3 N-m. When the plane is in East-West direction the torque is 0.4 N-m. The value of magnetic induction is (Neglect earth's magnetic field)
  • 0.2 T
  • 0.3 T
  • 0. 4 T
  • 0.1 T
  • 0.05 T
A wire of length 2 m carrying a current of 1 A is bent to form a circle, the magnetic moment of the coil is
  • 2π A – m2
  • 2)
    Physics-Moving Charges and Magnetism-82518.png
  • π A – m2

  • Physics-Moving Charges and Magnetism-82519.png
Consider two straight parallel conductors A and B separated by a distance x and carrying individual currents iA and iB respectively. If the two conductors attract each other, it indicates that
  • the two currents are parallel in direction
  • the two currents are anti-parallel in direction
  • the magnetic lines induction are parallel
  • the magnetic lines of induction are parallel to length of conductors
A and B are two infinitely long straight parallel conductors. C is another straight conductor of length lm kept parallel to A and B as shown in the figure. Then the force experienced by C is
Physics-Moving Charges and Magnetism-82521.png
  • towards A equal to 0.6 × 10-5 N
  • towards B equal to 5.4 × 10-5 N
  • towards A equal to 5.4 × 10-5 N
  • towards B equal to 0.6 × 10-5 N
A wire PQR is bent as shown in figure and is placed in a region of uniform magnetic field B. The length of PQ = QR = l. A current I ampere flows through the wire as shown. The magnitude of the force on PQ and QR will be
Physics-Moving Charges and Magnetism-82523.png
  • BIl, 0
  • 2BIl,0
  • 0, BIl
  • 0, 0
Two long conductors, separated by a distance d carry currents I1 and I2 in the same direction. They exert a force F on each other. Now the current in one of them is increased to two times and its direction is reversed. The distance is also increased to 3 d. The new value of the force between them is
  • -2F
  • F/3
  • -2F/3
  • -F/3
Three long straight wires A, B and C are carrying currents as shown in figure. Then the resultant force on B is directed
Physics-Moving Charges and Magnetism-82526.png
  • perpendicular to the plane of paper and outward
  • perpendicular to the plane of paper and inward
  • towards A
  • towards B
0:0:1


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