JEE Questions for Physics Moving Charges And Magnetism Quiz 9 - MCQExams.com

The electron in the beam of a television tube moves horizontally from south to north. The vertical component of the earth\'s magnetic field points down. The electron is deflected towards
  • West
  • Ne deflection
  • East
  • North to south
An electron (mass = 9.1 × 10–31 kg; charge = 1.6 × 10–19 C) experiences no deflection if subjected to an electric field of 3.2 × 105 V/m, and a magnetic field of 2.0 × 10–3 Wb/m2. Both the fields are normal to the path of electron and to each other. If the electric field is removed, then the electron will revolve in an orbit of radius
  • 45 m
  • 4.5 m
  • 0.45 m
  • 0.045 m
A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is
  • qEy2
  • qE2y
  • qEy
  • q2Ey
A man carrying suitable instruments for measuring electric and magnetic field passes by a stationary electron with velocity V. Then these instruments will note
  • Electric field
  • Magnetic field
  • Both a and b
  • None of these
An electron rotates about a proton, the induced magnetic field is 14 Tat the centre, find out the angular velocity of electron if radius of rotation is 0.5 nm
  • 4.4 × 1017 rad/sec
  • 4.4 × 1012 rad/sec
  • 3.14 × 10–15 rad/sec
  • 4.2 × 1010 rad/sec
The force on a charged particle moving with a velocity v in a magnetic field B is not
  • Perpendicular to both v and B
  • Maximum if v is perpendicular to B
  • Maximum if v is parallel to B
  • Zero if v is parallel to B
A charged particle enters a uniform magnetic field with a certain speed at right angles to it. In the magnetic field a change could occur in its
  • Kinetic energy
  • Angular momentum
  • Linear momentum
  • Speed

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    Physics-Moving Charges and Magnetism-82918.png

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A uniform magnetic field B = 1.2 mT is directed vertically upward throughout the volume of a laboratory chamber. A proton (mp = 1.67 × 10–27 kg) enters the laboratory horizontally from south to north. Calculate the magnitude of centripetal acceleration of the proton if its speed is 3 × 107 m/s
  • 3.45 × 1012 m/s2
  • 1.67 × 1012 m/s2
  • 5.25 × 1012 m/s2
  • 2.75 × 1012 m/s2
A positive charge is moving towards an observer. The direction of magnetic induction is
  • Clockwise
  • Anticlockwise
  • Right
  • Left
Proton, Deutron 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 rp, rd and rα. Which one of the follwoing relation is correct
  • rα = rp = rd
  • rα= rpd
  • rα> rd> rp
  • rα = rd> rp
The magnetic dipole moment of a current loop is independent of
  • Magnetic field in which it is lying
  • Number of turns
  • Area of the loop
  • Current in the loop

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  • Physics-Moving Charges and Magnetism-82925.png
  • 2)
    Physics-Moving Charges and Magnetism-82926.png
  • Zero

  • Physics-Moving Charges and Magnetism-82927.png
Two thin long parallel wires separated by a distance b are carrying a current i amp each. The magnitude of the force per unit length exerted by one wire on the other is

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  • 2)
    Physics-Moving Charges and Magnetism-82929.png

  • Physics-Moving Charges and Magnetism-82930.png

  • Physics-Moving Charges and Magnetism-82931.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 Nm. When the plane is in East-West direction the torque is 0.4 Nm. 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 current carrying straight wire is kept along the axis of a circular loop carrying a current. The straight wire
  • Will exert an inward force on the circular loop
  • Will exert an outward force on the circular loop
  • Will exert a force on the circular loop parallel to itself
  • Will not exert any force on the circular loop
Two straight parallel wires, both carrying 10 ampere in the same direction attract each other with a force of 1 × 10–3 N. If both currents are doubled, the force of attraction will be
  • 1 × 10–3N
  • 2 × 10–3 N
  • 4 × 10–3 N
  • 0.25 × 10–3 N
Uniform magnetic field B is directed vertically upwards and 3 wires of equal length L, carrying equal current i are lying in a horizontal plane such that the first one is along north, second one along north-east and the third one at 60° north of east. Force exerted by magnetic field B on them is
  • Zero on the first
  • 2)
    Physics-Moving Charges and Magnetism-82936.png

  • Physics-Moving Charges and Magnetism-82937.png
  • BiL on all of them
The radius of a circular loop is r and a current i is flowing in it. The equivalent magnetic moment will be
  • ir
  • 2 πir
  • iπr2

  • Physics-Moving Charges and Magnetism-82939.png
The deflection in a moving coil galvanometer is
  • Directly proportional to the torsional constant
  • Directly proportional to the number of turns in the coil
  • Inversely proportional to the area of the coil
  • Inversely proportional to the current flowing

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  • 2)
    Physics-Moving Charges and Magnetism-82944.png

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  • Physics-Moving Charges and Magnetism-82946.png
A moving coil galvanometer has N number of turns in a coil of effective area A, it carries a current I. The magnetic field B is radial. The torque acting on the coil is
  • NA2B2I
  • NABI2
  • N2ABI
  • NABI

Physics-Moving Charges and Magnetism-82949.png
  • NAIB
  • 2NAIB
  • 2πNAIB
  • 4πNAIB
A small coil of N turns has area A and a current I flows through it. The magnetic dipole moment of this coil will be
  • NI / A
  • NI2A
  • N2AI
  • NIA
Two long parallel conductors carry currents in opposite directions as shown. One conductor carries a current of 10 A and the distance between the wires is d = 10 cm. Current I is adjusted so that the magnetic field at P is at a distance of 5 cm to the right of the 10A current. Value of i is
Physics-Moving Charges and Magnetism-82952.png
  • 40 A
  • 30 A
  • 20 A
  • 10 A
A rectangular loop carrying a current i is placed in a uniform magnetic field B. The area enclosed by the loop is A. If there are n turns in the loop, the torque acting on the loop is given by

  • Physics-Moving Charges and Magnetism-82954.png
  • 2)
    Physics-Moving Charges and Magnetism-82955.png

  • Physics-Moving Charges and Magnetism-82956.png

  • Physics-Moving Charges and Magnetism-82957.png
An electron moves with a constant speed v along a circle of radius r. Its magnetic moment will be (e is the electron\'s charge)
  • evr
  • 2)
    Physics-Moving Charges and Magnetism-82958.png
  • πr2ev
  • 2πrev
Four wires each of length 2.0 metres are bent into four loops P, Q, R and S and then suspended into uniform magnetic field. Same current is passed in each loop. Which statement is correct
Physics-Moving Charges and Magnetism-82960.png
  • Couple on loop P will be the highest
  • Couple on loop Q will be the highest
  • Couple on loop R will be the highest
  • Couple on loop S will be the highest
A current carrying rectangular coil is placed in a uniform magnetic field. In which orientation, the coil will not tend to rotate
  • The magnetic field is parallel to the plane of the coil
  • The magnetic field is perpendicular to the plane of the coil
  • The magnetic field is at 45° with the plane of the coil
  • Always in any orientation
A current carrying loop is free to turn in a uniform magnetic field. The loop will then come into equilibrium when its plane is inclined at
  • 0° to the direction of the field
  • 45° to the direction of the field
  • 90° to the direction of the field
  • 135° to the direction of the field
The expression for the torque acting on a coil having area of cross-section A, number of turns n, placed in a magnetic field of strength B, making an angle θ with the normal to the plane of the coil, when a current i is flowing in it, will be
  • ni AB tan θ
  • ni AB cos θ
  • ni AB sin θ
  • ni AB
The pole pieces of the magnet used in a pivoted coil galvanometer are
  • Plane surfaces of a bar magnet
  • Plane surfaces of a horse-shoe magnet
  • Cylindrical surfaces of a bar magnet
  • Cylindrical surfaces of a horse-shoe magnet
A metallic loop is placed in a magnetic field. If a current is passed through it, then
  • The ring will feel a force of attraction
  • The ring will feel a force of repulsion
  • It will move to and fro about its centre of gravity
  • None of the above
Two parallel conductors A and B of equal lengths carry currents I and 10 I, respectively, in the same direction. Then
  • A and B will repel each other with same force
  • A and B will attract each other with same force
  • A will attract B, but B will repel A
  • A and B will attract each other with different forces
Three long, straight and parallel wires carrying currents are arranged as shown in figure. The force experienced by 10 cm length of wire Q is
Physics-Moving Charges and Magnetism-82963.png
  • 1.4 × 10–4 N towards right
  • 1.4 × 10–4 N towards left
  • 2.6 × 10–4 N to the right
  • 2.6 × 10–4 N to the left
A 100 turns coil shown in figure carries a current of 2 amp in a magnetic field B = 0.2 Wb/m2. The torque acting on the coil is
Physics-Moving Charges and Magnetism-82965.png
  • 0.32 Nm tending to rotate the side AD out of the page
  • 0.32 Nm tending to rotate the side AD into the page
  • 0.0032 Nm tending to rotate the side AD out of the page
  • 0.0032 Nm tending to rotate the side AD into the page
A current of 5 ampere is flowing in a wire of length 1.5 metres. A force of 7.5 N acts on it when it is placed in a uniform magnetic field of 2 tesla. The angle between the magnetic field and the direction of the current is
  • 30°
  • 45°
  • 60°
  • 90°
A conductor in the form of a right angle ABC with AB = 3 cm and BC = 4 cm carries a current of 10 A. There is a uniform magnetic field of 5 T perpendicular to the plane of the conductor. The force on the conductor will be
  • 1.5 N
  • 2.0 N
  • 2.5 N
  • 3.5 N
The coil of a galvanometer consists of 100 turns and effective area of 1 square cm. The restoring couple is 10–8 N–m/radian. The magnetic field between the pole pieces is 5T. The current sensitivity of this galvanometer will be
  • 5 × 104 rad/μ amp
  • 5 × 10–6 per amp
  • 2 x 10–7 per amp
  • 5 rad/μ amp
A rectangular coil 20 cm × 20 cm has 100 turns and carries a current of 1 A. It is placed in a uniform magnetic field B = 0.5 T with the direction of magnetic field parallel to the plane of the coil. The magnitude of the torque required to hold this coil in this position is
  • Zero
  • 200 N–m
  • 2 N–m
  • 10 N-m
In hydrogen atom, the electron is making 6.6 × 1015 rev/sec around the nucleus in an orbit of radius 0.528 Å. The magnetic moment (A – m2) will be
  • 1 × 10–15
  • 1 × 10–10
  • 1 × 10–23
  • 1 × 10–27
A triangular loop of side l carries a current I. It is placed in a magnetic field B such that the plane of the loop is in the direction of B. The torque on the loop is
  • Zero
  • 2)
    Physics-Moving Charges and Magnetism-82972.png

  • Physics-Moving Charges and Magnetism-82973.png

  • Physics-Moving Charges and Magnetism-82974.png
Three long, straight and parallel wires carrying current are arranged as shown in the figure. The wire C which carries a current of 5.0 amp is so placed that it experiences no force. The distance of wire C from wire D is then
Physics-Moving Charges and Magnetism-82976.png
  • 9 cm
  • 7 cm
  • 5 cm
  • 3 cm
A vertical wire carrying a current in the upward direction is placed in horizontal magnetic field directed towards north. The wire will experience a force directed towards
  • North
  • South
  • East
  • West
A coil carrying electric current is placed in uniform magnetic field, then
  • Torque is formed
  • E.M.F. is induced
  • Both (a) and (b) are correct
  • None of the above
A circular loop carrying a current is replaced by an equivalent magnetic dipole. A point on the axis of the loop is
  • An end-on position
  • A broad side-on position
  • Both (a) and (b)
  • Neither (a) nor (b)
A power line lies along the East–West direction and carries a current of 10 ampere. The force per metre due to the earth\'s magnetic field of 10–4 tesla is
  • 10–5 N
  • 10–4 N
  • 10–3 N
  • 10–2 N
In ballistic galvanometer, the frame on which the coil is wound is non-metallic to
  • Avoid the production of induced e.m.f.
  • Avoid the production of eddy currents
  • Increase the production of eddy currents
  • Increase the production of induced e.m.f.
Two parallel beams of electrons moving in the same direction produce a mutual force
  • Of attraction in plane of paper
  • Of repulsion in plane of paper
  • Upwards perpendicular to plane of paper
  • Downwards perpendicular to plane of paper
Current i is carried in a wire of length L. If the wire is turned into a circular coil, the maximum magnitude of torque in a given magnetic field B will be

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    Physics-Moving Charges and Magnetism-82980.png

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