Practice question
Question
What happens to the current in a purely inductive AC circuit when the frequency of the source
decreases?
Explanation
**Peak current** I_peak = V_peak/R for resistor, I_rms = V_rms/R, V_peak = √2 V_rms, for 200 V rms, V_peak=282.8 V, I_peak=282.8/80=3.535 A, rms I=200/80=2.5 A, average over complete cycle zero because positive and negative halves cancel. In a purely inductive circuit, X_L = ω L , and current I = (V/X_L) . Decreasing frequency reduces ω , lowering X_L , which increases the current since I is inversely proportional to X_L . Applying X_L = ωL, X_C = 1/ωC, Z = √(R² + (X_L - X_C)²), I_rms = V_rms/Z, P = V_rms I_rms cosφ, V_s/V_p = N_s/N_p, calculation gives It increases, consistent with phasor analysis
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