Electricity 2 — AC Circuits
RMS voltage, reactance, series RLC impedance, and resonance — with the impedance dip plotted live.
DC was a steady push. AC alternates — voltage swings like a sine wave, 60 times a second. Two new components come alive: inductors and capacitors, which resist change rather than current. Their tug-of-war creates resonance.
- 01 Peak vs RMS "120 V" from the wall is not the peak — it is the RMS value: the steady DC voltage that would deliver the same power. For a sine wave, RMS = peak/√2.
- 02 Reactance — resistance that depends on frequency An inductor fights changing current: the faster the change, the harder it fights — X_L grows with frequency. A capacitor is the mirror image: it blocks DC…
- 03 Series RLC — impedance In series, the reactances fight: X_L pulls the voltage one way in time, X_C the other. What the source feels is the impedance — resistance and the net…
- 04 Resonance Sweep the frequency and there is exactly one point where X_L = X_C — they cancel, impedance collapses to just R, and current peaks. That frequency is the…
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