Inductors and transient behavior — During changes in current, the ability of a conductor/coil to generate a counter-emf within itself is called:

Introduction:
Inductors resist changes in current by creating an induced voltage that opposes the change. Distinguishing the phenomenon from the resulting voltage is crucial for precise terminology in circuits, power supplies, and signal conditioning.

Given Data / Assumptions:

• Single coil or conductor with changing current.
• No external secondary coil is required (not mutual induction).
• Linear operation assumed for clarity.

Concept / Approach:

According to Faraday’s law, a changing current produces a changing magnetic field, which links the same conductor and induces a voltage opposing the change (Lenz’s law). The ability or property is termed self-induction; the induced opposing voltage is often called back emf. The unit of inductance (henry) quantifies how much voltage appears for a given di/dt but is not the effect itself.

Step-by-Step Solution:

Verification / Alternative check:

Opening a current through a relay coil causes a high voltage spike (back emf) due to self-induction, commonly clamped by a flyback diode—textbook evidence of the phenomenon.

Why Other Options Are Wrong:

• back emf: Names the voltage result, not the property.
• a henry: Unit of inductance, not the effect.
• impedance: General AC opposition (includes R and X), not specifically the self-inductive mechanism.
• mutual coupling: Requires two coils; question is about a single conductor.

Common Pitfalls:

• Using “back emf” and “self-induction” interchangeably; keep property vs. outcome distinct.
• Assuming only coils exhibit self-induction; any conductor carrying changing current does, though coils increase the effect.

Final Answer:

self-induction