Electromagnetic induction – Core meaning of Faraday’s law Statement: “Faraday’s law states that relative motion between a magnetic field and a coil induces a voltage across the coil.”

Introduction / Context:
Faraday’s law is fundamental to transformers, generators, and inductors. It relates induced electromotive force (emf) to the rate of change of magnetic flux linkage through a coil. This item checks your qualitative grasp of what causes induction.

Given Data / Assumptions:

• We consider a coil with N turns linking magnetic flux.
• Either the magnetic field varies in time, or the coil moves relative to the field (or both).
• Idealized conditions suffice to judge the statement.

Concept / Approach:

Faraday’s law: induced emf e = − dλ/dt where λ = N*Φ is flux linkage. A nonzero emf arises when flux linkage changes with time. Relative motion between coil and magnetic field is one common cause of changing flux (generator action). Another cause is a time-varying field with a stationary coil (transformer action). The statement cites one valid cause—relative motion—which is consistent with the law, so it is true as worded.

Step-by-Step Solution:

Verification / Alternative check:

Practical examples include bicycle dynamos (motion-induced emf) and transformers (time-varying field-induced emf without motion).

Why Other Options Are Wrong:

“False unless flux is constant” contradicts the law—the emf requires changing, not constant, flux. Coil resistance does not determine whether emf is induced, only the resulting current if a closed path exists.

Common Pitfalls:

Thinking motion is required—transformers show that motion is not necessary; any dλ/dt suffices.

Final Answer:

True.