Alternating-Current Circuits (Physics)

Recall cards on alternating-current circuits. AC sources: DC versus AC, the v = V0 sin(omega t) and i = I0 sin(omega t) forms, peak versus instantaneous notation, and US and European mains values. Simple AC circuits: the resistor in phase, the capacitor's current leading and the inductor's current lagging by pi/2, capacitive reactance XC = 1/(omega C), inductive reactance XL = omega L, their frequency dependence, and phasors. Series RLC circuits: impedance Z = sqrt(R^2 + (XL - XC)^2), the AC Ohm's law I0 = V0/Z, the phase angle, and the element voltages. Power: rms current and voltage, the average-power formulas, the power factor cos(phi), and why only resistors dissipate. Resonance: XL = XC, omega0 = 1/sqrt(LC), minimum impedance, maximum current and power, and the quality factor. Transformers: the voltage and current turns ratios, step-up and step-down, power conservation, and high-voltage transmission.