Phase of current above resonance: For a series RLC circuit operating at a frequency higher than its resonant frequency, how does the current phase compare to the applied voltage?

Introduction / Context:
Understanding the phase behavior of series RLC circuits relative to resonance is fundamental in tuning and filter design. The nature of the net reactance (inductive or capacitive) determines whether the current leads or lags the source voltage.

Given Data / Assumptions:

• Series RLC circuit, ideal components.
• Operating frequency f > f_r (resonant frequency).

Concept / Approach:
At resonance, X_L = X_C and the current is in phase with voltage. Above resonance, X_L > X_C, so the net reactance is inductive: Z ≈ R + j(X_L − X_C) with a positive imaginary part. In inductive circuits, current lags voltage.

Step-by-Step Reasoning:

Verification / Alternative check:
Below resonance (f < f_r), the circuit is capacitive (current leads). Exactly at resonance, current and voltage are in phase. These boundaries confirm the inductive (lagging) nature above f_r.

Why Other Options Are Wrong:

• Leads / in phase: These apply below or at resonance, not above.
• Zero: The current is not zero; it is lower than at resonance but finite.

Common Pitfalls:

• Reversing lead/lag behavior for inductors and capacitors.

Final Answer:
lags the applied voltage