JEE Questions for Physics Electromagnetic Induction Quiz 5 - MCQExams.com

Two different loops are concentric and lie in the same plane. The current in the outer loop is clockwise and increasing with time. The induced current in the inner loop then, is
  • Clockwise
  • Zero
  • Counter clockwise
  • In a direction that depends on the ratio of the loop radii
According to Faraday\'s law of electromagnetic induction
  • The direction of induced current is such that it opposes the cause producing it
  • The magnitude of induced e.m.f. produced in a coil is directly proportional to the rate of change of magnetic flux
  • The direction of induced e.m.f. is such that it opposes the cause producing it
  • None of the above

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  • 2)
    Physics-Electromagnetic Induction-68822.png

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The magnetic field in a coil of 100 turns and 40 square cm area is increased from 1 tesla to 6 tesla in 2 second. The magnetic field is perpendicular to the coil. The e.m.f. generated in it is
  • 104 V
  • 1.2 V
  • 1.0 V
  • 10–2 V
Lenz\'s law gives
  • The magnitude of the induced e.m.f.
  • The direction of the induced current
  • Both the magnitude and direction of the induced current
  • The magnitude of the induced current
The north pole of a bar magnet is moved swiftly downward towards a closed coil and then second time it is raised upwards slowly. The magnitude and direction of the induced currents in the two cases will be of
Physics-Electromagnetic Induction-68827.png
  • (a)
  • (b)
  • (c)
  • (d)
A metallic ring connected to a rod oscillates freely like a pendulum. If now a magnetic field is applied in horizontal direction so that the pendulum now swings through the field, the pendulum will
Physics-Electromagnetic Induction-68828.png
  • Keep oscillating with the old time period
  • Keep oscillating with a smaller time period
  • Keep oscillating with a larger time period
  • Come to rest very soon
A circular coil of 500 turns of wire has an enclosed area of 0.1 m2 per turn. It is kept perpendicular to a magnetic field of induction 0.2 T and rotated by 180° about a diameter perpendicular to the field in 0.1 sec. How much charge will pass when the coil is connected to a galvanometer with a combined resistance of 50 ohms?
  • 0.2 C
  • 0.4 C
  • 2 C
  • 4 C
A coil of 100 turns and area 5 square centimetre is placed in a magnetic field B = 0.2 T. The normal to the plane of the coil makes an angle of 60° with the direction of the magnetic field. The magnetic flux linked with the coil is
  • 5 × 10–3 Wb
  • 5 × 10–3 Wb
  • 10–2 Wb
  • 10–4 Wb

Physics-Electromagnetic Induction-68831.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 = 90°, the charge undergoes linear but accelerated motion along the y-axis
A solenoid is 1.5 m long and its inner diameter is 4.0 cm. It has three layers of windings of 1000 turns each and carries a current of 2.0 amperes. The magnetic flux for a cross-section of the solenoid is nearly
  • 2.5 × 10–7 weber
  • 6.31 × 10–6 weber
  • 5.2 × 10–5 weber
  • 4.1 × 10–5 weber
A coil of 40 Ω resistance has 100 turns and radius 6 mm is connected to ammeter of resistance of 160 ohms. Coil is placed perpendicular to the magnetic field. When coil is taken out of the field, 32 µC charge flows through it. The intensity of magnetic field will be
  • 6.55 T
  • 5.66 T
  • 0.655 T
  • 0.566 T
Faraday\'s laws are consequence of conservation of
  • Energy
  • Energy and magnetic field
  • Charge
  • Magnetic field
A student is performing the experiment of Resonance Column. The diameter of the column tube is 4 cm. The frequency of the tuning fork is 512 Hz. The air temperature is 38°C in which the speed of sound is 336 m/s. The zero of the metre scale coincides with the top end of the Resonance Column tube. When the first resonance occurs, the reading of the water level in the column is
  • 14.0 cm
  • 15.2 cm
  • 16.4 cm
  • 17.6 cm
In the diagram shown if a bar magnet is moved along the common axis of two single turn coils A and B in the direction of arrow
Physics-Electromagnetic Induction-68838.png
  • Current is induced only in A & not in B
  • Induced currents in A & B are in the same direction
  • Current is induced only in B and not in A
  • Induced currents in A &B are in opposite directions
A square coil of side 25 cm having 1000 turns is rotated with a uniform speed in a magnetic field about an axis perpendicular to the direction of the field. At an instant t the e.m.f. induced in the coil is e = 200 sin 100 π t. The magnetic induction is
  • 0.50 T
  • 0.01 T
  • 10–3 T
  • 0.1 T
The formula for induced e.m.f. in a coil due to change in magnetic flux through the coil is (There A = area of the coil, B = magnetic field)

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    Physics-Electromagnetic Induction-68841.png

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Lenz\'s law is expressed by the following formula (here e = induced e.m.f., ɸ = magnetic flux in one turn and N = number of turns)

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  • 2)
    Physics-Electromagnetic Induction-68845.png

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A magnet is dropped down an infinitely long vertical copper tube
  • The magnet moves with continuously increasing velocity and ultimately acquires a constant terminal velocity
  • The magnet moves with continuously decreasing velocity and ultimately comes to rest
  • The magnet moves with continuously increasing velocity but constant acceleration
  • The magnet moves with continuously increasing velocity and acceleration
An aluminum ring B faces an electromagnet A. The current I through A can be altered
Physics-Electromagnetic Induction-68848.png
  • Whether I increases or decreases, B will not experience any force
  • If I decreases, A will repel B
  • If I increases A will attract B
  • If I increases, A will repel B
A small piece of metal wire is dragged across the gap between the pole pieces of a magnet in 0.5 second. The magnetic flux between the pole pieces is known to be 8 × 10–4 Wb. The e.m.f. induced in the wire is
  • 16 mV
  • 1.6 V
  • 1.6 mV
  • 16 V
When a bar magnet falls through a long hollow metal cylinder fixed with its axis vertical, the final acceleration of the magnet is
  • Equal to zero
  • Less than g
  • Equal to g
  • Equal to g in the beginning and then more than g

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  • Physics-Electromagnetic Induction-68852.png
  • AB

  • Physics-Electromagnetic Induction-68853.png

  • Physics-Electromagnetic Induction-68854.png
A magnet NS is suspended from a spring and while it oscillates, the magnet moves in and out of the coil C. The coil is connected to a galvanometer G. Then as the magnet oscillates,
Physics-Electromagnetic Induction-68855.png
  • G shows deflection to the left and right with constant amplitude
  • G shows deflection on one side
  • G shows no deflection
  • G shows deflection to the left and right but the amplitude steadily decreases
A coil having n turns and resistance R Ω is connected with a galvanometer of resistance 4 R Ω This combination is moved in time t seconds from a magnetic field W1 weber to W2 weber. The induced current in the circuit is

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  • 2)
    Physics-Electromagnetic Induction-68857.png

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A square loop of side 22 cm is converted into circular loop in 0.4 s. A uniform magnetic field of 0.2 T directed normal to the loop then the e.m.f. induced in the loop is
  • 6.6 × 10–3 V
  • 6.6 × 10–5 V
  • 4.6 × 10–4 V
  • 4.60 × 10–8 V
If a coil of 40 turns and area 4.0 cm2 is suddenly removed from a magnetic field, it is observed that a charge of 2.0 × 10–4 C flows into the coil. If the resistance of the coil is 80 Ω, the magnetic flux density in Wb/m2 is
  • 0.5
  • 1.0
  • 1.5
  • 2.0
In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency ω in a magnetic field B. The maximum value of e.m.f. generated in the coil is
  • N.A.B.
  • N.A.B.R
  • N.A.B. ω
  • N.A.B.R. ω
The diagram below shows two coils A and B placed parallel to each other at a very small distance. Coil A is connected to an ac supply. G is a very sensitive galvanometer. When the key is closed
Physics-Electromagnetic Induction-68864.png
  • Constant deflection will be observed in the galvanometer for 50 Hz supply
  • Visible small variations will be observed in the galvanometer for 50 Hz input
  • Oscillations in the galvanometer may be observed when the input ac voltage has a frequency of 1 to 2 Hz
  • No variation will be observed in the galvanometer even when the input ac voltage is 1 or 2 Hz
An infinitely long cylinder is kept parallel to a uniform magnetic field B directed along positive z–axis. The direction of induced current as seen from the z axis will be
  • Clockwise of the +ve z axis
  • Anticlockwise of the +ve z axis
  • Zero
  • Along the magnetic field
The magnetic flux across a loop of resistance 10 Ω is given by ɸ = 5t2 – 4t + 1 weber. How much current is induced in the loop after 0.2 sec?
  • 0.4 A
  • 0.2 A
  • 0.04 A
  • 0.02 A
There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then
  • Current is induced in the loop in the anticlockwise direction
  • Current is induced in the loop in the clockwise direction
  • AC in induced in the loop
  • No current is induced in the loop
A 50 Hz AC current of peak value 2 A flows through one of the pair of coils. If the mutual inductance between the pair of coils is 150 mH, then the peak value of voltage induced in the second coil is
  • 30 π V
  • 60 π V
  • 15 π V
  • 300 π V
  • 3 π V
A square loop of wire, side length 10 cm is placed at angle of 45° with a magnetic field that changes uniformly from 0.1 T to zero in 0.7 seconds. The induced current in the loop (its resistance is 1 Ω) is
  • 1.0 mA
  • 2.5 mA
  • 3.5 mA
  • 4.0 mA
A rectangular coil ABCD is rotated anticlockwise with a uniform angular velocity about the axis shown in diagram below. The axis of rotation of the coil as well as the magnetic field B are horizontal. The induced e.m.f. in the coil would be maximum when
Physics-Electromagnetic Induction-68869.png
  • The plane of the coil is horizontal
  • The plane of the coil makes an angle of 45° with the magnetic field
  • The plane of the coil is at right angles to the magnetic field
  • The plane of the coil makes an angle of 30° with the magnetic field
A 10 metre wire kept in east–west direction is falling with velocity 5m/sec perpendicular to the field 0.3 × 10–4Wb / m2. The induced e.m.f. across the terminal will be
  • 0.15 V
  • 1.5 mV
  • 1.5 V
  • 15.0 V
Two rails of a railway track insulated from each other and the ground are connected to a milli voltmeter. What is the reading of voltmeter, when a train travels with a speed of 180 km/hr along the track. Given that the vertical component of earth\'s magnetic field is 0.2 × 10–4 weber/m2 and the rails are separated by 1 metre?
  • 10–2 volt
  • 10–4 volt
  • 10–3 volt
  • 1 volt
When a metallic plate swings between the poles of a magnet
  • No effect on the plate
  • Eddy currents are set up inside the plate and the direction of the current is along the motion of the plate
  • Eddy currents are set up inside the plate and the direction of the current oppose the motion of the plate
  • Eddy currents are set up inside the plate
An aeroplane in which the distance between the tips of wings is 50 m is flying horizontally with a speed of 360 km/hr over a place where the vertical components of earth magnetic field is 2.0 × 10–4weber / m2. The potential difference between the tips of wings would be
  • 0.1 V
  • 1.0 V
  • 0.2 V
  • 0.01 V
A coil of wire of a certain radius has 600 turns and a self-inductance of 108 mH. The self-inductance of a 2nd similar coil of 500 turns will be
  • 74 mH
  • 75 mH
  • 76 mH
  • 77 mH
A player with 3 m long iron rod runs towards east with a speed of 30 km/hr. Horizontal component of earth\'s magnetic field is 4 × 10–5 Wb/m2. If he is running with rod in horizontal and vertical positions, then the potential difference induced between the two ends of the rod in two cases will be
  • Zero in vertical position and 1 × 10–3 V in horizontal position
  • 1 × 10–3 V in vertical position and zero is horizontal position
  • Zero in both cases
  • 1 × 10–3 V in both cases
A coil of area 80 square cm and 50 turns in rotating with 2000 revolutions per minute about an axis perpendicular to a magnetic field of 0.05 tesla. The maximum value of the e.m.f. developed in it is

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  • 2)
    Physics-Electromagnetic Induction-68876.png

  • Physics-Electromagnetic Induction-68877.png

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A conducting rod of length l is falling with a velocity v perpendicular to a uniform horizontal magnetic field B. The potential difference between its two ends will be

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  • 2)
    Physics-Electromagnetic Induction-68881.png

  • Physics-Electromagnetic Induction-68882.png

  • Physics-Electromagnetic Induction-68883.png
A conducting wire is moving towards right in a magnetic field B. The direction of induced current in the wire is shown in the figure. The direction of magnetic field will be
Physics-Electromagnetic Induction-68884.png
  • In the plane of paper pointing towards right
  • In the plane of paper pointing towards left
  • Perpendicular to the plane of paper and downwards
  • Perpendicular to the plane of paper and upwards
The current carrying wire and the rod AB are in the same plane. The rod moves parallel to the wire with a velocity v. Which one of the following statements is true about induced e.m.f. in the rod
Physics-Electromagnetic Induction-68885.png
  • End A will be at lower potential with respect to B
  • A and B will be at the same potential
  • There will be no induced e.m.f. in the rod
  • Potential at A will be higher than that at B
A long horizontal metallic rod with length along the east-west direction is falling under gravity. The potential difference between its two ends will
  • Be zero
  • Be constant
  • Increase with time
  • Decrease with time
Two similar circular loops carry equal currents in the same direction. On moving the coils further apart, the electric current will
  • Remain unaltered
  • Increases in one and decreases in the second
  • Increase in both
  • Decrease in both
A metal rod moves at a constant velocity in a direction perpendicular to its length. A constant uniform magnetic field exists in space in a direction perpendicular to the rod as well as its velocity. Select the correct statement (s) from the following
  • The entire rod is at the same electric potential
  • There is an electric field in the rod
  • The electric potential is highest at the centre of the rod and decreases towards its ends
  • The electric potential is lowest at the centre of the rod and increases towards its ends
A conducting wire is dropped along east-west direction, then
  • No e.m.f. is induced
  • No induced current flows
  • Induced current flows from west to east
  • Induced current flows from east to west
The magnetic induction in the region between the pole faces of an electromagnet is 0.7 weber/m2. The induced e.m.f. in a straight conductor 10 cm long, perpendicular to B and moving perpendicular both to magnetic induction and its own length with a velocity 2m/sec is
  • 0.08 V
  • 0.14 V
  • 0.35 V
  • 0.07 V
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