Power components in AC circuits Which quantity is alternately stored and returned (shuttled back and forth) between the source and reactive elements in an AC circuit?

Introduction / Context:
Power in AC systems can be decomposed into real (true), reactive, and apparent components. Understanding the physical meaning of each is essential for power factor correction, transformer sizing, and minimizing energy costs in industrial systems.

Given Data / Assumptions:

• Sinusoidal steady-state operation.
• Reactive elements (capacitors or inductors) are present.
• Losses in ideal reactive components are negligible (they do not dissipate average power).

Concept / Approach:
True power (P, measured in watts) represents net energy converted to heat, work, or light per unit time. Reactive power (Q, measured in var) represents energy that oscillates between the source and the electric or magnetic fields of capacitors and inductors each cycle. Apparent power (S, in VA) is the product of RMS voltage and current and is the vector sum S^2 = P^2 + Q^2.

Step-by-Step Solution:

Verification / Alternative check:
Check limiting cases: a purely resistive circuit has Q = 0 and only P flows; a purely reactive circuit has P = 0 and Q ≠ 0 (no net energy transfer over a cycle, only exchange).

Why Other Options Are Wrong:

Common Pitfalls:
Equating high apparent power with high losses; forgetting that poor power factor increases current without increasing useful work.

Final Answer:
Reactive power