AC coil behavior — field direction change: When the current through a coil reverses direction in an AC excitation scenario, what happens to the direction of the magnetic field around the coil?

Introduction / Context:
Inductors and transformers rely on time-varying magnetic fields. Understanding how magnetic field direction relates to current direction is foundational for applying right-hand rules, analyzing AC behavior, and predicting induced voltages in nearby coils.

Given Data / Assumptions:

• A single coil carrying current that can reverse (as in AC).
• Geometry and coil orientation are fixed.
• We consider the near field around the conductor/coil.

Concept / Approach:
The magnetic field direction is directly tied to current direction by the right-hand rule. If current reverses, the field direction also reverses. The field does not vanish permanently; it simply changes sign as current changes sign. Magnitude depends on current magnitude; direction depends on current polarity.

Step-by-Step Solution:

Verification / Alternative check:
Transformer operation depends on this; the alternating current causes alternating flux that induces voltage in secondary windings with corresponding polarity reversals each half cycle.

Why Other Options Are Wrong:

• Does not change / only increases: Contradict the right-hand rule.
• Disappears: Only true at the instant current passes through zero; it returns with opposite direction immediately after.

Common Pitfalls:
Confusing instantaneous zero crossings (momentary field collapse) with permanent disappearance; forgetting the field orientation flips with current polarity.

Final Answer:
reverses direction