Series RLC — same current in all series elements: Assume a single-loop series RLC circuit in steady-state AC where a clamp-on ammeter at the source lead reads 5 A (rms). What is the inductor current (rms)?

Introduction / Context:
In any single-loop series circuit (R, L, and/or C in series), the same instantaneous current flows through every element because there is only one current path. This question tests the core idea of series topology and how it applies to an inductor’s branch current reading.

Given Data / Assumptions:

• Single-loop series RLC driven by a sinusoidal source.
• The measured circuit (source-lead) current is 5 A rms.
• Ideal lumped elements; parasitics and measurement burden are negligible.

Concept / Approach:
Kirchhoff’s Current Law applied to a series loop implies a single branch; therefore the current is identical through R, L, and C at every instant. Phasor relationships change how voltage distributes (phase shifts), but not the series current equality. Thus the inductor current must equal the source current.

Step-by-Step Solution:

Verification / Alternative check:
Measure with an ammeter inserted in series before the inductor and again between L and C; both readings match the source current (within instrument tolerance).

Why Other Options Are Wrong:

Common Pitfalls:
Confusing series (same current) with parallel (same voltage). Also, mixing up current magnitude with reactive voltage magnitudes, which can be large at resonance without changing current equality.

Final Answer:
5 A