Induction terminology — name the concept: Identify the correct term for the phenomenon in which a changing current in one coil induces a voltage in a nearby second coil.

Introduction / Context:
Transformers, wireless power transfer, and many sensing applications rely on one circuit inducing a response in another via magnetic fields. Knowing the correct terminology helps you read datasheets and design notes accurately.

Given Data / Assumptions:

• Two separate coils placed such that magnetic flux from one can link the other.
• Current in the first coil is time varying, producing a changing magnetic field.
• The second coil experiences a changing flux linkage and therefore an induced voltage.

Concept / Approach:
The induced voltage in the second coil due to current change in the first is described by mutual inductance M. The coupling coefficient k (0 to 1) quantifies how much of the first coil’s flux links the second. Self-inductance L, by contrast, refers to voltage induced in the same coil that carries the changing current.

Step-by-Step Solution:

Verification / Alternative check:
Transformers are practical demonstrations: primary current changes induce secondary voltages proportional to the mutual inductance (through the turns ratio framework).

Why Other Options Are Wrong:
Electrical isolation: a benefit of transformer design but not the induction mechanism’s name.

Self-inductance: refers to a coil inducing voltage in itself from its own current change.

Coefficient of coupling: a dimensionless parameter k describing linkage efficiency, not the fundamental phenomenon’s name.

Common Pitfalls:
Confusing mutual inductance with simple capacitive coupling. Assuming mutual inductance requires physical contact; it is through the magnetic field.

Final Answer:
Mutual inductance