JEE Main Physics: Faraday's law and Lenz's law Practice Questions
14 free multiple-choice questions on Faraday's law and Lenz's law (Electricity and Magnetism) for JEE Main Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more JEE Main questions in the app →Q1. When a magnetic dipole is placed in a uniform magnetic field, the magnetic dipole experiences a force only if:
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Correct answer: C — The field is non-uniform
A magnetic dipole experiences a force (F⃗ = I(vec(dl) × B⃗)) only when the magnetic field is non-uniform or if the magnetic dipole is rotating within the field. For a simple static case, if the field is uniform, the force is zero.
Q2. When a conductor moves in a magnetic field, the induced EMF arises due to:
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Correct answer: A — the change in magnetic flux linked with the conductor
The EMF is induced because the conductor cuts the magnetic flux lines, causing the magnetic flux linked with it to change, per Faraday's law.
Q3. Lenz's law is fundamentally based on which principle of physics?
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Correct answer: A — Conservation of Energy
Lenz's law is a direct consequence of the law of conservation of energy. The opposition to the change in flux causes an opposing force, which results in energy dissipation or conservation in the system.
Q4. The magnitude of the induced EMF in a conductor is directly proportional to:
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Correct answer: A — The rate of change of magnetic flux linkage
The induced EMF is proportional to the rate at which the magnetic flux passing through the circuit changes.
Q5. Magnetic flux is defined as the measure of:
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Correct answer: B — the total number of magnetic field lines passing through a given area
Magnetic flux (Φ_B) is the measure of the total magnetic field lines passing perpendicularly through a given surface area.
Q6. If the magnetic flux linked with a coil is kept constant, the induced EMF in the coil will be:
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Correct answer: C — zero
According to Faraday's law (mathcalE = -dΦ_B/dt), if the flux (Φ_B) is constant, the rate of change of flux is zero, thus the induced EMF is zero.
Q7. If the magnetic flux linked with a circuit is zero, the magnetic field passing through the circuit must be:
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Correct answer: A — Zero
Magnetic flux (Φ_B) is the product of the magnetic field (B) and the area (A). If the flux is zero, it implies either B=0 or A=0. For a meaningful scenario where the system exists, zero flux implies zero magnetic field or zero area enclosed.
Q8. Lenz's law is fundamentally a statement of which physical principle?
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Correct answer: D — Conservation of energy
Lenz's law dictates the direction of the induced current to oppose the change in magnetic flux, which is a direct consequence of the conservation of energy.
Q9. If the magnetic flux linked with a loop is constant, what is the induced electromotive force (EMF) in that loop?
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Correct answer: A — Zero EMF
According to Faraday's law, the induced EMF is proportional to the rate of change of magnetic flux. If the flux is constant (i.e., dΦ_B/dt = 0), the induced EMF is zero.
Q10. Lenz's law is a consequence of which principle?
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Correct answer: A — Conservation of Angular Momentum
Lenz's law is a statement of the conservation of energy, ensuring that the induced effect opposes the change that caused it.
Q11. According to Faraday's law of electromagnetic induction, the magnitude of the induced electromotive force (EMF) in a circuit is proportional to:
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Correct answer: B — the rate of change of magnetic flux linked with the circuit
Faraday's law states that the induced EMF is directly proportional to the rate of change of magnetic flux linked with the circuit.
Q12. When the magnetic flux passing through a coil is increasing, the direction of the induced current will be determined by:
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Correct answer: D — The direction required to oppose the change in flux
Lenz's law states that the induced current flows in a direction that opposes the change in magnetic flux that produced it.
Q13. The magnitude of the induced EMF in a circuit is directly proportional to the rate of change of magnetic flux. This statement is consistent with which law?
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Correct answer: B — Faraday's Law of Induction
Faraday's law of induction states that the magnitude of the induced EMF is equal to the magnitude of the rate of change of the magnetic flux linked with the circuit.
Q14. Lenz's law is fundamentally based on the principle that the change in magnetic flux induces an EMF that creates a current opposing the change in flux. This opposition is a manifestation of which physical principle?
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Correct answer: A — Conservation of Energy
Lenz's law ensures the conservation of energy. The induced EMF generates a current that creates a back (opposing) magnetic field. This opposition ensures that the magnetic field lines are conserved, and the process is adiabatic, consistent with the conservation of energy and the principle that energy cannot be created or destroyed.
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