Assertion and Reason Questions Chapter-6 Electromagnetic Induction
Assertion (A) and other labelled Reason (R). Select the correct answer to these
questions from the options as given below.
A. Both A and R are true, and R is the correct explanation of A.
B. Both A and R are true, but R is not the correct explanation of A.
C. A is true, but R is false.
D. A is false, but R is true.
1. Assertion (A): Electromagnetic induction occurs when a conductor moves
through a magnetic field.
Reason (R): The motion of the conductor changes the magnetic field
around it.
2. Assertion (A): Faraday's law of electromagnetic induction states that the
induced emf is directly proportional to the rate of change of magnetic flux.
Reason (R): The magnetic flux can change due to the movement of
the magnet or the coil.
3. Assertion (A): Lenz's law states that the direction of the induced current is
such that it opposes the change that produced it.
Reason (R): This law is a consequence of the conservation of
energy.
4. Assertion (A): Self-induction is the process where a changing current in a
coil induces an emf in the same coil.
Reason (R): Self-induction depends on the rate of change of
current in the coil.
5. Assertion (A): The induced emf in a coil is independent of the number of
turns in the coil.
Reason (R): The induced emf is solely determined by the magnetic
field strength.
6. Assertion (A): A transformer works on the principle of electromagnetic
induction.
Reason (R): It converts AC to DC voltage.
7. Assertion (A): The back emf in a motor reduces the current flowing through
it.
Reason (R): Back emf opposes the applied voltage.
8. Assertion (A): Induced emf can be generated by changing the area of a coil in
a magnetic field.
Reason (R): Changing the area of a coil alters the magnetic flux
through it.
9. Assertion (A): A changing magnetic field can induce an electric field in a
nearby conductor.
Reason (R): This phenomenon is known as electromagnetic induction.
10. Assertion (A): Eddy currents are induced currents that flow in loops within
conductors.
Reason (R): Eddy currents produce their own magnetic fields that
oppose the original magnetic field.
11. Assertion (A): The magnitude of induced emf increases with the speed of
relative motion between the magnet and the coil.
Reason (R): Faster motion results in a greater change in magnetic
flux over time.
12. Assertion (A): The induced current in a closed loop creates a magnetic
field.
Reason (R): The direction of this magnetic field can be determined
using the right-hand grip rule.
13. Assertion (A): A moving magnet can induce current in a stationary coil.
Reason (R): This is due to a change in the magnetic flux through
the coil.
14. Assertion (A): Electromagnetic induction is a unidirectional phenomenon.
Reason (R): The direction of induced current depends on the
direction of motion of the conductor.
15. Assertion (A): The efficiency of a transformer is defined as the ratio of
output power to input power.
Reason (R): A transformer always operates at 100% efficiency.
16. Assertion (A): The induced emf in a coil can be measured using a voltmeter.
Reason (R): A voltmeter is designed to measure the potential
difference across the terminals of the coil.
17. Assertion (A): The magnetic field lines around a current-carrying conductor
are closed loops.
Reason (R): This is a fundamental property of magnetic fields.
18. Assertion (A): Induction heating uses the principle of electromagnetic
induction to generate heat.
Reason (R): Induction heating is efficient for cooking and
industrial processes.
19. Assertion (A): The induced emf in a coil does not depend on the orientation
of the coil in the magnetic field.
Reason (R): The magnetic field strength is uniform across all
orientations.
20. Assertion (A): A galvanometer can be converted into an ammeter by adding a
low-resistance shunt.
Reason (R): The shunt allows most of the current to bypass the
galvanometer, preventing damage.
21. Assertion (A): A solenoid can produce a uniform magnetic field when a
current passes through it.
Reason (R): The magnetic field inside a solenoid is directly
proportional to the current flowing through it.
22. Assertion (A): A current-carrying loop in a magnetic field experiences a
torque.
Reason (R): The torque is due to the interaction between the
magnetic field and the current.
23. Assertion (A): The induced emf can be increased by increasing the number of
turns in the coil.
Reason (R): More turns result in greater total magnetic flux
linkage.
24. Assertion (A): Electromagnetic induction can occur in a conductor even if it
is not moving.
Reason (R): Changes in the magnetic field around the conductor can
induce current.
25. Assertion (A): The direction of induced current can be predicted using
Lenz's law.
Reason (R): Lenz's law states that induced current flows in a
direction to oppose the change in flux.
26. Assertion (A): Transformers are used to step up or step down AC voltages.
Reason (R): The operation of a transformer is based on the
principle of self-induction.
27. Assertion (A): The strength of the induced current is influenced by the
speed at which the magnetic field changes.
Reason (R): A faster change in the magnetic field leads to a
greater induced emf.
28. Assertion (A): The magnetic flux through a surface is independent of the
angle at which the magnetic field lines intersect the surface.
Reason (R): Magnetic flux depends only on the strength of the
magnetic field.
29. Assertion (A): The induced emf can be measured by a digital voltmeter.
Reason (R): A digital voltmeter provides a direct reading of the
induced emf.
30. Assertion (A): The change in magnetic flux can be caused by moving a magnet
towards or away from a coil.
Reason (R): This movement changes the number of magnetic field
lines passing through the coil.
31. Assertion (A): When a coil is moved into a magnetic field, an emf is induced
in the coil.
Reason (R): The induced emf is proportional to the speed of the
coil's movement.
32. Assertion (A): A galvanometer can detect small currents due to the torque
exerted on a coil in a magnetic field.
Reason (R): The coil experiences a torque that causes it to
rotate, moving the pointer on the scale.
33. Assertion (A): A magnetic field can induce a current in a nearby conductor
without direct contact.
Reason (R): This phenomenon is known as magnetic induction.
34. Assertion (A): The flux linkage in a coil is the product of the magnetic
flux and the number of turns in the coil.
Reason (R): Increasing the number of turns increases the induced
emf.
35. Assertion (A): The magnetic field inside a long solenoid is uniform and
parallel to its axis.
Reason (R): This uniformity arises from the closely spaced turns
of wire in the solenoid.
36. Assertion (A): The induced current always flows in a direction that opposes
the change causing it.
Reason (R): This is a manifestation of the conservation of
momentum.
37. Assertion (A): The greater the magnetic field strength, the greater the
induced emf.
Reason (R): The induced emf is proportional to the strength of the
magnetic field.
38. Assertion (A): Inductive reactance opposes the flow of current in AC
circuits.
Reason (R): Inductive reactance increases with the frequency of
the alternating current.
39. Assertion (A): Electromagnetic induction can be observed in both AC and DC
circuits.
Reason (R): Induction occurs when there is a change in current in
the circuit.
40. Assertion (A): The use of ferromagnetic materials in transformers enhances
their efficiency.
Reason (R): Ferromagnetic materials increase the magnetic
permeability of the transformer core.
41. Assertion (A): Electromagnetic induction can be used to generate electric
power.
Reason (R): Generators utilize the principles of electromagnetic
induction to convert mechanical energy into electrical energy.
42. Assertion (A): The induced current in a loop decreases if the magnetic field
strength decreases.
Reason (R): A weaker magnetic field leads to a smaller change in
magnetic flux.
43. Assertion (A): The induced emf in a coil is directly proportional to the
rate of change of magnetic flux through it.
Reason (R): This relationship is expressed by Faraday's law of
induction.
44. Assertion (A): The frequency of the alternating current affects the
operation of inductive components in circuits.
Reason (R): Inductive reactance increases with frequency,
affecting the overall impedance of the circuit.
45. Assertion (A): Lenz's law is a consequence of the conservation of energy.
Reason (R): It explains that induced currents will always flow in
a direction that opposes the change in magnetic flux.
46. Assertion (A): Inductors store energy in the form of a magnetic field.
Reason (R): The energy stored in an inductor is proportional to
the square of the current flowing through it.
47. Assertion (A): The induced emf can be negative.
Reason (R): A negative induced emf indicates a reversal in the
direction of current flow.
48. Assertion (A): When a conductor cuts through magnetic field lines, an emf is
induced.
Reason (R): The induced emf depends on the speed at which the
conductor cuts the lines.
49. Assertion (A): The energy efficiency of transformers is generally high.
Reason (R): Transformers can transfer electrical energy with
minimal losses.
50. Assertion (A): A changing electric field can induce a magnetic field.
Reason (R): This phenomenon is described by Maxwell's equations.