Class 12 Electromagnetic Induction CBSE Questions & Answers

Class 12 · Electromagnetic Induction

This is Physics Class 12 Electromagnetic Induction CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
electromagnetic induction i.e currents can be induced in coils (Select the best)
  • A
    Only if the coil moves and magnet also moves in the same direction
  • B
    Only if the magnet moves
  • C
    Only if the coil moves
  • D
    if relative motion of coil and magnet is present.
    Correct
2
When a bar magnet is pushed towards the coil connected in series with a galvanometer, the pointer in the galvanometer G
  • A
    oscillates
  • B
    shows deflection while bar is in motion
    Correct
  • C
    does not move
  • D
    shows deflection while bar is stationary
3
When current carrying coil \({{\rm{C}}_{\rm{2}}}\) is moved towards the coil \({{\rm{C}}_{\rm{1}}}\) connected in series with a galvanometer, the pointer in the galvanometer G
  • A
    oscillates
  • B
    shows deflection while \({{\rm{C}}_{\rm{2}}}\) is in motion .
    Correct
  • C
    does not move
  • D
    shows deflection while \({{\rm{C}}_{\rm{2}}}\) is stationary
4
Coils \({{\rm{C}}_{\rm{1}}}\) and \({{\rm{C}}_{\rm{2}}}\) are stationary. \({{\rm{C}}_{\rm{1}}}\) connected in series with a galvanometer while \({{\rm{C}}_{\rm{2}}}\) is connected to a battery through a tapping key. If the tapping key is pressed and released the galvaometer
  • A
    oscillates
  • B
    shows deflection while current in \({{\rm{C}}_{\rm{2}}}\) is changing .
    Correct
  • C
    does not move
  • D
    shows deflection while \({{\rm{C}}_{\rm{2}}}\) is stationary
5
Magnetic flux through a surface S is given by
  • A
    \(\int \mu_0 \vec{B}. \vec{ds}\)
  • B
    \(\int \vec{B}× \vec{ds}\)
  • C
    \( \vec{B}. \vec{ds}\)
  • D
    \(\int \vec{B}. \vec{ds}\).
    Correct
6
According to Farady's law
  • A
    The magnitude of the induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit. .
    Correct
  • B
    The magnitude of the induced emf in a circuit is equal to the time of change of magnetic flux through the circuit.
  • C
    The magnitude of the induced emf in a circuit is proportional to the time of change of magnetic flux through the circuit.
  • D
    The magnitude of the induced emf in a circuit is equal change of magnetic flux through the circuit.
7
According to Farady's law for a coil having N turns
  • A
    \(\mu_0 N\frac{d\phi_B}{dt}\)
  • B
    \(-N\frac{d\phi_B}{dt}\).
    Correct
  • C
    \(-\frac{d\phi_B}{dt}\)
  • D
    \(\mu_0 N^2 \frac{d\phi_B}{dt}\)
8
Coils \({{\rm{C}}_{\rm{1}}}\) and \({{\rm{C}}_{\rm{2}}}\) are stationary. \({{\rm{C}}_{\rm{1}}}\) connected in series with one very small diwali bulb while \({{\rm{C}}_{\rm{2}}}\) is connected to a battery .If the connection is suddenly snapped
  • A
    the bulb absorbs light
  • B
    nothing happens to the bulb
  • C
    the bulb keeps glowing
  • D
    the bulb glows momentarily.
    Correct
9
According to Lenz’s law
  • A
    The induced emf is proportional change in magnetic flux that produced it.
  • B
    The induced emf is proportional rate of change in magnetic flux that produced it.
  • C
    The polarity of induced emf is such that it tends to produce a current which aids the change in magnetic flux that produced it.
  • D
    The polarity of induced emf is such that it tends to produce a current which opposes the change in magnetic flux that produced it. .
    Correct
10
If the polarity of induced emf is such that it tends to produce a current which aids the change in magnetic flux that produced it, which conservation law is violated?
  • A
    conservation of energy.
    Correct
  • B
    conservation of charge
  • C
    conservation of mass
  • D
    conservation of momentum
11
A rectangular conductor PQRS in which the conductor PQ is free to move is kept in a magnetic field B ,which is perpendicular to the PQRS which lies in a single plane. If the conductor PQ has a length l,moves with a speed v, then induced emf is
  • A
    Bl/v
  • B
    Bv/l
  • C
    Blv.
    Correct
  • D
    Bv
12
Moving conductor rod is 0.10 m long, and moves with a velocity of 2.5 m/s perpendicular to the agnetic field. If the circuit is completed with has a resistance of 0.03Ω is the total resistance of the loop is and B is 0.60 T. Find the motional emf, the induced current,
  • A
    0.15 V,5.0 A.
    Correct
  • B
    0.20 V,6.5 A
  • C
    0.15 V,6.0 A
  • D
    0.25 V,5.0 A
13
A rectangular conductor PQRS in which the conductor PQ is free to move is kept in a magnetic field B ,which is perpendicular to the PQRS which lies in a single plane. If the conductor PQ of length l is pushed by a force F then the power supplied is (assuming a circuit ressistance r)
  • A
    \(\frac{B^2l^2v^2}{r^2}\)
  • B
    \(\frac{B^2l^2v^3}{r}\)
  • C
    \(\frac{B^2l^2v^2}{r}\).
    Correct
  • D
    \(\frac{B^3l^2v^2}{r}\)
14
A rectangular conductor PQRS in which the conductor PQ is free to move is kept in a magnetic field B ,which is perpendicular to the PQRS which lies in a single plane. If the conductor PQ of length l is pushed by a force F and circuit has resistance r,the power loss in the resistance is
  • A
    \(\frac{B^2l^2v^3}{r}\)
  • B
    \(\frac{B^2l^2v^2}{r^2}\)
  • C
    \(\frac{B^3l^2v^2}{r}\)
  • D
    \(\frac{B^2l^2v^2}{r}\).
    Correct
15
Eddy Currents are
  • A
    induced currents that circulate throughout the volume of a material similar to swirling eddies in a river.
    Correct
  • B
    induced solar currents that circulate throughout a river and are swirling .
  • C
    plasma currents
  • D
    gaseous currents