At resonance, a passive parallel RLC network is often described as exhibiting a "flywheel" effect. Which statement best characterizes its behavior at resonance?

Introduction:
Parallel resonant (tank) circuits are widely used in tuning and filtering. The term "flywheel" refers to how energy shuttles between electric and magnetic fields, sustaining oscillatory behavior with minimal loss near resonance. This question probes conceptual understanding of energetic exchange and the practical meaning of resonance in passive networks.

Given Data / Assumptions:

• Parallel RLC network, passive components.
• Sinusoidal steady state near resonance.
• Finite but small losses (nonzero R) so Q is finite.

Concept / Approach:
At resonance, reactive branch currents in L and C are large and largely equal and opposite, causing minimal source current. Energy alternately stores in C (electric field) and L (magnetic field), akin to a flywheel storing kinetic energy. With a sustaining source, this exchange produces a strong selective response that we describe as oscillatory behavior at or near the resonant frequency.

Step-by-Step Solution:
1) Recognize resonance: net reactive susceptance ≈ 0 in parallel tanks.2) Energy transfer cycle: capacitor charges and discharges, inductor current builds and collapses.3) With minimal losses, stored energy persists over many cycles, giving a "flywheel" effect.4) The response is oscillatory in time when excited; with an active sustaining mechanism, the tank can form the core of an oscillator.

Verification / Alternative check:
Consider ring-down: excite the tank briefly and remove the source. The voltage/current decay exponentially at a rate set by Q, demonstrating free oscillation and the energy-storage "flywheel" effect until losses dissipate energy.

Why Other Options Are Wrong:
Flywheel only: captures energy storage but omits the inherently oscillatory exchange.

Oscillate only: describes the motion but ignores the energy-storage metaphor.

None of the above: contradicts standard textbook descriptions of resonant tanks.

Ring only when driven by DC: DC does not sustain AC resonance; a transient can start ringing, but sustained oscillation needs AC drive or active feedback.

Common Pitfalls:
Thinking passive tanks self-oscillate without excitation (they require initial energy or active feedback) or that resonance means zero current everywhere. In parallel tanks, branch currents are large but cancel at the input.

Final Answer:
both of the above