Practice question
Question
In an AC circuit with only a capacitor, what happens to the impedance if the capacitance is decreased?
Explanation
**Capacitor average power** zero over complete cycle because P=V I =½ V_peak I_peak sin2ωt average zero, energy stored in field, not dissipated, unlike resistor. For 15 μF, 60 Hz, X_C=176.8 Ω, V_rms=110 V, I_rms=0.622 A, illustrating lower C higher X_C. In a purely capacitive circuit, impedance is X_C = (1/ω C) . Decreasing capacitance ( C ) increases X_C because they are inversely proportional, thus increasing the impedance. 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 and resonance condition X_L = X_C.
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