JEE Questions for Physics Moving Charges And Magnetism Quiz 10 - MCQExams.com

Magnetic dipole moment of a rectangular loop is
  • Inversely proportional to current in loop
  • Inversely proportional to area of loop
  • Parallel to plane of loop and proportional to area of loop
  • Perpendicular to plane of loop and proportional to area of loop
If m is magnetic moment and B is the magnetic field, then the torque is given by

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    Physics-Moving Charges and Magnetism-82986.png

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  • Physics-Moving Charges and Magnetism-82988.png
Two long parallel copper wires carry currents of 5 A each in opposite directions. If the wires are separated by a distance of 0.5 m, then the force between the two wires is
  • 10–5 N, attractive
  • 10–5 N, repulsive
  • 2 × 10–5 N, attractive
  • 2 × 10–5 N, repulsive
Due to the flow of current in a circular loop of radius R, the magnetic induction produced at the centre of the loop is B. The magnetic moment of the loop is
(μ0 = Permeability constant)

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The magnetic moment of a circular coil carrying current is
  • Directly proportional to the length of the wire in the coil
  • Inversely proportional to the length of the wire in the coil
  • Directly proportional to the square of the length of the wire in the coil
  • Inversely proportional to the square of the length of the wire in the coil
A long wire A carries a current of 10 amp. Another long wire B, which is parallel to A and separated by 0.1 m from A, carries a current of 5 amp, in the opposite direction to that in A. What is the magnitude and nature of the force experienced per unit length of B (μ0 = 4π × 10–7 weber/amp–m)
  • Repulsive force of 10–4 N/m
  • Attractive force of 10–4 N/m
  • Repulsive force of 2π × 10–5 N/m
  • Attractive force of 2π × 10–5 N/m
A stream of electrons is projected horizontally to the right. A straight conductor carrying a current is supported parallel to electron stream and above it. If the current in the conductor is form left to right then what will be the effect on electron stream
  • The electron stream will be pulled upward
  • The electron stream will be pulled downward
  • The electron stream will be retarted
  • The electron beam will be speeded up towards the right
What is the shape of magnet used in moving coil galvanometer to make the magnetic fields radial?
  • Concave
  • Horse shoe magnet
  • Convex
  • None of these
Two parallel wires of length 9 m each are separated by a distance 0.15 m. If they carry equal currents in the same direction and exert a total force of 30 × 10–7 N on each other, then the value of the current must be
  • 2.5 amp
  • 3.5 amp
  • 1.5 amp
  • 0.5 amp
A current i flows in a circular coil of radius r. If the coil is placed in a uniform magnetic field B with its plane parallel to the field, magnitude of the torque that acts on the coil is
  • Zero
  • 2πriB
  • πr2iB
  • 2πr2iB
A, B and C are parallel conductors of equal length carrying currents I, I and 2I respectively. Distance between A and B is x. Distance between B and C is also x. F1 is the force exerted by B on A and F2 is the force exerted by C on A. Choose the correct answer
Physics-Moving Charges and Magnetism-83000.png
  • F1 = 2 F2
  • F2 = 2F1
  • F1 = F2
  • F1 = –F2
A straight conductor carries a current of 5 A. An electron travelling with a speed of 5 × 106 ms–1 parallel to the wire at a distance of 0.1 m from the conductor, experience a force of
  • 8 × 10–20 N
  • 3.2 × 10–19 N
  • 8 × 10–18 N
  • 1.6 × 10–19 N
Two galvanometers A and B require 3 mA and 5 mA respectively to produce the same deflection of 10 divisions. Then
  • A is more sensitive than B
  • B is more sensitive than A
  • A and B are equally sensitive
  • Sensitiveness of B is 5/3 times that of A
A beam of electrons and protons move parallel to each other in the same direction, then they
  • Attract each other
  • Repel each other
  • No relation
  • Neither attract nor repel
If the current is doubled, the deflection is also doubled in
  • A tangent galvanometer
  • A moving coil galvanometer
  • Both (a) and (b)
  • None of the above
Two long conductors, separated by a distance d carry current 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 directions is reversed. The distance is also increased to 3d. The new value of the force between them is
  • –2F
  • F/3
  • 2F/3
  • –F/3
The resultant magnetic moment of neon atom will be
  • Infinity
  • μB
  • Zero
  • μB/2
A one metre long wire is lying at right angles to the magnetic field. A force of 1 kg wt. is acting on it in a magnetic field of 0.98 tesla. The current flowing in it will be
  • 100 A
  • 10 A
  • 1 A
  • Zero
The magnetic field on the axis of a long solenoid having n turns per unit length and carrying a current is
  • μ0ni
  • μBn2i
  • μBni2
  • None of these
The ratio of magnetic field and magnetic moment at the centre of a current carrying circular loop is x. When both the current and radius is doubled then the ratio will be

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    Physics-Moving Charges and Magnetism-83009.png

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  • Physics-Moving Charges and Magnetism-83011.png
Two concentric circular loops of radii R and 2R carry currents of 2I and I respectively in opposite sense (i.e., clockwise in one coil and counter-clockwise in the other coil.) The resultant magnetic field at their common centre is

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    Physics-Moving Charges and Magnetism-83014.png

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  • Physics-Moving Charges and Magnetism-83016.png
The force between two parallel current carrying wires is independent of
  • Their distance of separation
  • The length of the wires
  • The magnitude of currents
  • The radii of the wires
  • The medium in which they are placed
A coil carrying a heavy current and having large number of turns is mounted in aN–S vertical plane and a current flows in clockwise direction. A small magnetic needle at its centre will have its North pole in
  • East-North direction
  • West-North direction
  • East-South direction
  • West-South direction
A loop carrying current I lies in the x-yplane as shown in the figure. The unit vector k is coming out of the plane of the paper. The magnetic moment of the current loop is
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    Physics-Moving Charges and Magnetism-83019.png

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A circular current carrying coil has a radius R. The distance from the centre of the coil on the axis where the magnetic induction will be 1/8th to its value at the centre of the coil, is

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    Physics-Moving Charges and Magnetism-83024.png

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The field normal to the plane of a wire of n turns and radius r which carries a current i is measured on the axis of the coil at a small distance h from the centre of the coil. This is smaller than the field at the centre by the fraction

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    Physics-Moving Charges and Magnetism-83029.png

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The magnetic field at the centre of a circular coil of radius r is π times that due to a long straight wire at a distance r from it, for equal currents. Figure here shows three cases: in all cases the circular part has radius r and straight ones are infinitely long. For same current the B field at the centre P in cases 1, 2, 3 have the ratio
Physics-Moving Charges and Magnetism-83033.png

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    Physics-Moving Charges and Magnetism-83035.png

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Two straight long conductors AOB and COD are perpendicular to each other and carry currents i1 and i2. The magnitude of the magnetic induction at a point P at a distance a from the point Oin a direction perpendicular to the plane ACBD is

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    Physics-Moving Charges and Magnetism-83040.png

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A cell is connected between the points A and C of a circular conductor ABCD of centre O with angle AOC = 60°. If B1 and B2are the magnitudes of the magnetic fields at Odue to the currents in ABC and ADC respectively, the ratio B1 / B2 is
Physics-Moving Charges and Magnetism-83044.png
  • 0.2
  • 6
  • 1
  • 5
An infinitely long conductor PQR is bent to form a right angle as shown. A current I flows through PQR. The magnetic field due to this current at the point M is H1. Now another infinitely long straight conductor QS is connected at Q so that the current is I/2 in QR as well as in QS, the current in PQ remaining unchanged. The magnetic field at M is now H2. The ratio H1/H2 is given by
Physics-Moving Charges and Magnetism-83046.png
  • 1/2
  • 1
  • 2/3
  • 2
A thin flexible wire of length L is connected to two adjacent fixed points carries a current I in the clockwise direction, as shown in the figure. When system is put in a uniform magnetic field of strength B going into the plane of paper, the wire takes the shape of a circle. The tension in the wire is
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    Physics-Moving Charges and Magnetism-83050.png

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A coil having N turns is wound tightly in the form of a spiral with inner and outer radii a and b respectively. When a current I passes through the coil, the magnetic field at the centre is

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    Physics-Moving Charges and Magnetism-83055.png

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A non-planar loop of conducting wire carrying a current I is placed as shown in the figure. Each of the straight sections of the loop is of length 2a. The magnetic field due to this loop at the point P(a, 0, a) points in the direction
Physics-Moving Charges and Magnetism-83059.png

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    Physics-Moving Charges and Magnetism-83061.png

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    Physics-Moving Charges and Magnetism-83067.png

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Two circular concentric loops of radii r1= 20 cm and r2 = 30 cm are placed in the XY plane as shown in the figure. A current I = 7 amp is flowing through them. The magnetic moment of this loop system is
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    Physics-Moving Charges and Magnetism-83079.png

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An ionized gas contains both positive and negative ions. If it is subjected simultaneously to an electric field along the +x direction and a magnetic field along the +z direction, then
  • Positive ions deflect towards +y direction and negative ions towards –y direction
  • All ions deflect towards +y direction
  • All ions deflect towards –y direction
  • Positive ions deflect towards –y direction and negative ions towards +y direction
A current I flows in an infinitely long wire with cross-section in the form of a semicircular ring of radius R. The magnitude of the magnetic induction along its axis is

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    Physics-Moving Charges and Magnetism-83084.png

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A particle of mass m and charge q moves with a constant velocity v along the positive x direction. It enters a region containing a uniform magnetic field B directed along the negative z direction, extending from x = a to x = b. The minimum value of v required so that the particle can just enter the region x >b is

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    Physics-Moving Charges and Magnetism-83089.png

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  • Physics-Moving Charges and Magnetism-83091.png
For a positively charged particle moving in a x–y plane initially along the x–axis, there is a sudden change in its path due to the presence of electric and/or magnetic fields beyond P. The curved path is shown in the x – y plane and is found to be non-circular. Which one of the following combinations is possible
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    Physics-Moving Charges and Magnetism-83095.png

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A horizontal rod of mass 10 gm and length 10 cm is placed on a smooth plane inclined at an angle of 60° with the horizontal, with the length of the rod parallel to the edge of the inclined plane. A uniform magnetic field of induction B is applied vertically downwards. If the current through the rod is 1.73 ampere, then the value of B for which the rod remains stationary on the inclined plane is
  • 1.73 tesla
  • 2)
    Physics-Moving Charges and Magnetism-83099.png
  • 1 tesla
  • None of these
Two long wires are hanging freely. They are joined first in parallel and then in series and then are connected with a battery. In both cases, which type of force acts between the two wires
  • Attraction force when in parallel and repulsion force when in series
  • Repulsion force when in parallel and attraction force when in series
  • Repulsion force in both cases
  • Attraction force in both cases
A wire of length 2 m is bent into a circular loop. When a current of 1 A is passed through the loop, then the magnetic moment of the loop is

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    Physics-Moving Charges and Magnetism-83103.png

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Physics-Moving Charges and Magnetism-83107.png
  • No force
  • A stretching force
  • A compressive force
  • A torque
A charged particle is projected in a plane perpendicular to a uniform magnetic field. The area bounded by the path described by the particle is proportional to
  • The velocity
  • The momentum
  • The kinetic energy
  • None of these
Wires 1 and 2 carrying currents i1 and i2 respectively are inclined at an angle θ to each other. What is the force on a small element dl of wire 2 at a distance of r from wire 1 (as shown in figure) due to the magnetic field of wire 1?
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    Physics-Moving Charges and Magnetism-83110.png

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A conducting loop carrying a current I is placed in a uniform magnetic field pointing into the plane of the paper as shown. The loop will have a tendency to
Physics-Moving Charges and Magnetism-83114.png
  • Contract
  • Expand
  • Move towards +ve x–axis
  • Move towards –ve x–axis
A current carrying loop is placed in a uniform magnetic field in four different orientations, I, II, III and IV. Arrange them in the decreasing order of potential energy
Physics-Moving Charges and Magnetism-83116.png
  • I > III > II > IV
  • I > II > III > IV
  • I > IV > II > III
  • III> IV > I > II

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    Physics-Moving Charges and Magnetism-83120.png

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Two insulated 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
Physics-Moving Charges and Magnetism-83124.png
  • The two rings rotate into a common place
  • The inner ring oscillates about its initial position
  • The inner ring stays stationary while the outer one moves into the plane of the inner ring
  • The outer ring stays stationary while the inner one moves into the plane of the outer ring
0:0:1


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