Electromagnetic Induction Class 12 Physics Assertion and Reason Questions 2026-27 | Chapter 6
Electromagnetic Induction Class 12 Physics Assertion and Reason Questions
35 original Class 12 Physics Assertion–Reason questions with answers and explanations covering magnetic flux, Faraday’s laws, Lenz’s law, induced EMF/current, motional EMF, self-induction, mutual induction and current-syllabus boundaries.
1. Core Chapter 6 Assertion–Reason Questions
These questions target the current Chapter 6 concepts and the recurring practice themes visible across current CBSE-oriented resources: magnetic flux, Faraday’s law, Lenz’s law, induced EMF/current, motional EMF, self-induction and mutual induction. They are deliberately mixed across direct concepts, proportional reasoning, graph-based reasoning and misconception checks. Current search results for this topic repeatedly foreground the phrases “Electromagnetic Induction Class 12 Physics,” “Assertion and Reason,” “Faraday’s law,” “Lenz’s law,” “self-induction,” “mutual induction,” “motional EMF” and “CBSE 2026–27”; these terms are reflected naturally in the page rather than stuffed into the copy.
Assertion (A): The magnitude of induced emf is proportional to the rate of change of magnetic flux through the circuit.
Reason (R): Faraday’s law states that the induced emf magnitude is proportional to the time rate of change of magnetic flux linkage.
Assertion (A): A stationary closed coil placed in a perfectly uniform, time-independent magnetic field necessarily has an induced current.
Reason (R): Induced current is produced whenever magnetic flux is present through a closed circuit, even if that flux is constant.
Assertion (A): The induced current in a circuit opposes the change in magnetic flux that produces it.
Reason (R): Lenz’s law expresses conservation of energy in electromagnetic induction.
Assertion (A): A changing magnetic flux through a circuit can produce an induced emf even when the circuit is open.
Reason (R): A current requires a closed conducting path, but an emf can be induced in an open circuit.
Assertion (A): If the magnetic flux through a closed coil is constant, no induced emf is produced.
Reason (R): Faraday’s law gives induced emf from the time rate of change of flux linkage.
Assertion (A): For a uniform magnetic field, the magnetic flux through a plane coil depends on the angle between the field and the area vector.
Reason (R): Magnetic flux is Φ = BA cos θ, where θ is measured between B and the area vector.
Assertion (A): Rotating a coil in a uniform magnetic field can induce an emf.
Reason (R): A coil placed in a magnetic field can have magnetic flux through it even when it is not rotating.
Assertion (A): Changing the magnetic field through a stationary coil can induce an emf.
Reason (R): A change in B can change the magnetic flux when the coil’s area and orientation are fixed.
Assertion (A): A conductor moving through a magnetic field can experience a motional emf when its motion changes the magnetic flux linkage of the circuit.
Reason (R): Changing the linked flux can produce an induced emf.
Assertion (A): The negative sign in Faraday’s law determines the magnitude of induced emf.
Reason (R): The negative sign in Faraday’s law is used only to increase the numerical magnitude of the induced emf.
Assertion (A): If the rate of change of magnetic flux is doubled, the magnitude of induced emf doubles, for the same number of turns.
Reason (R): For a coil, |ε| = N|dΦ/dt|.
Assertion (A): For two coils with the same flux change per turn and the same time interval, the coil with more turns has a larger induced emf.
Reason (R): Induced emf is proportional to the number of turns linked by the changing flux.
Assertion (A): A magnetic flux of zero through a coil always means that no induced emf can occur.
Reason (R): Induced emf depends only on the instantaneous value of magnetic flux and not on how the flux changes with time.
Assertion (A): A coil may have non-zero magnetic flux through it while its induced emf is zero.
Reason (R): If the flux is constant, dΦ/dt = 0 even though Φ itself may be non-zero.
Assertion (A): Lenz’s law can be used to determine the direction of induced current.
Reason (R): The induced current produces a magnetic effect that opposes the change in flux responsible for induction.
Assertion (A): If a magnet is moved toward a conducting coil, the induced current produces a magnetic effect that opposes the approach.
Reason (R): Lenz’s law says that the induced effect always strengthens the change in magnetic flux.
Assertion (A): If a magnet is moved away from a conducting coil, the induced current reverses direction compared with the approach case.
Reason (R): The induced effect opposes the change in flux, so reversing the change reverses the induced-current direction.
Assertion (A): A large, steady magnetic flux through a closed coil is sufficient to maintain an induced current.
Reason (R): A steady magnetic flux always produces a continuous induced emf in a closed coil.
Assertion (A): Self-induction is the phenomenon in which a changing current in a coil induces an emf in the same coil.
Reason (R): The changing current changes the magnetic flux linked with that coil.
Assertion (A): The induced emf due to self-induction opposes the change in current producing it.
Reason (R): The self-induced emf follows Lenz’s law.
Assertion (A): For a coil of inductance L, the magnitude of self-induced emf is proportional to the rate of change of current.
Reason (R): The relation is ε = −L di/dt.
Assertion (A): Increasing the number of turns of a long solenoid can increase its self-inductance.
Reason (R): For fixed geometry, self-inductance depends strongly on the square of the number of turns.
Assertion (A): An inductor can store energy in its magnetic field.
Reason (R): The energy stored in an ideal inductor is stored as electrostatic energy between its turns.
Assertion (A): The energy stored in an ideal inductor is proportional to the square of current.
Reason (R): For an ideal inductor, U = ½LI².
Assertion (A): Mutual induction occurs when a changing current in one coil induces an emf in another nearby coil.
Reason (R): The changing current in the first coil changes the magnetic flux linked with the second coil.
Assertion (A): The mutual inductance between two coils is independent of their relative geometry.
Reason (R): Mutual inductance is determined only by the resistance of the two coils and is unaffected by their arrangement.
Assertion (A): If the rate of change of current in the primary coil is zero, the mutually induced emf in the secondary coil is zero, under ideal conditions.
Reason (R): Mutual induced emf is proportional to the rate of change of primary current.
Assertion (A): The SI unit of both self-inductance and mutual inductance is the henry.
Reason (R): Both quantities appear in induced-emf relations with the dimensions of inductance.
Assertion (A): In a simple ideal two-coil system, stronger magnetic coupling can increase the mutual inductance.
Reason (R): Stronger coupling means a larger fraction of the changing flux from one coil links the other.
Assertion (A): Self-induction and mutual induction are completely unrelated phenomena.
Reason (R): Self-induction occurs only because of electrostatic charge accumulation and has no connection with changing magnetic flux.
2. Application & Assessment-Aware Extension
Assertion (A): If a Φ–t graph has zero slope over an interval, the induced emf is zero over that interval.
Reason (R): Faraday’s law links induced emf to the time derivative, i.e. the slope, of the flux-time graph.
Assertion (A): For a simple closed circuit of constant resistance, the total induced charge for a given change in flux does not depend on how quickly the change occurs.
Reason (R): Using q = IΔt with Faraday’s law gives q = N|ΔΦ|/R for the same total flux change.
Assertion (A): A bar magnet falling through a conducting ring can have acceleration less than g while it is producing induced current.
Reason (R): The induced current produces a magnetic effect that opposes the changing flux and can provide a retarding force.
Assertion (A): For a fixed pair of coils, doubling the rate of change of primary current doubles the magnitude of mutually induced emf.
Reason (R): The relation |ε₂| = M|dI₁/dt| applies for fixed mutual inductance M.
Assertion (A): AC generator belongs to the core content of Chapter 6 in the current CBSE 2026–27 Physics curriculum.
Reason (R): The 2026–27 curriculum lists AC generator under Chapter 6: Electromagnetic Induction, not Chapter 7.
3. How to Solve Assertion–Reason Questions
Ignore the Reason first. Decide whether the Assertion is scientifically true or false.
Check the Reason independently. A related-looking statement can still be false.
If both are true, ask whether R actually explains why A is true. If not, choose B.
4. Current CBSE A–R Option Map
| Option | Meaning in the current 2026–27 Physics SQP |
|---|---|
| A | Both Assertion and Reason are true and Reason is the correct explanation of Assertion. |
| B | Both Assertion and Reason are true but Reason is not the correct explanation of Assertion. |
| C | Assertion is true but Reason is false. |
| D | Both Assertion and Reason are false. |
5. Common Chapter 6 Assertion–Reason Traps
A non-zero magnetic flux does not automatically mean induced EMF. The relevant quantity is dΦ/dt.
An open circuit can have induced EMF without a sustained induced current.
In Φ = BA cosθ, θ is the angle between B and the area vector, not the plane itself.
The induced effect opposes the change in flux, not simply the original magnetic field.
Self-induction involves the same coil; mutual induction involves a second coil.
Do not automatically import AC-generator and transformer questions into Chapter 6; CBSE 2026–27 lists them under Chapter 7.
6. High-Yield Concept Map for A–R Practice
| Concept | What an Assertion–Reason question may test |
|---|---|
| Magnetic flux | BA cosθ, area-vector convention, zero vs changing flux |
| Faraday’s laws | Rate of flux change, number of turns, average vs instantaneous EMF |
| Lenz’s law | Direction of induced current and conservation of energy |
| Induced current | Closed conducting path vs induced EMF in an open circuit |
| Motional EMF | Motion, changing flux linkage and standard ε = Bℓv arrangement |
| Self-induction | ε = −L dI/dt, opposition to current change, inductance |
| Mutual induction | ε₂ = −M dI₁/dt, flux linkage and coil coupling |
| Inductor energy | U = ½LI² and proportional reasoning |
7. Chapter 6 Study Resources
8. Final Revision Checklist
□ decide whether a statement requires changing flux, not merely magnetic field presence
□ use Φ = BA cosθ with the correct area-vector angle
□ distinguish induced EMF from induced current
□ apply Faraday’s law to average and rate-based situations
□ use Lenz’s law to determine the direction of the induced effect
□ distinguish self-induction from mutual induction
□ interpret the role of L and M in induced-emf relations
□ handle proportional reasoning involving turns, flux change and current change
□ recognise the current Chapter 7 boundary for AC generator and transformer
Research note: This is an original Learn Revise Hub practice resource. Current syllabus and assessment alignment are based on CBSE’s official 2026–27 Physics curriculum and Class XII SQP. Current search-intent research was used to identify recurring EMI practice topics, but no third-party question has been presented as an official CBSE question. The official curriculum states that content marked as excluded from NCERT for 2026–27 is not to be assessed in the Board examination.
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