AC Circuits
Sinusoidal voltages and currents, phasors, impedance, power factor and resonance.
Mains electricity is alternating current: a sinusoid at 50 Hz in India (60 Hz in the Americas). AC is easy to transform between voltage levels, which is why it powers the grid. Analysing AC circuits uses phasors and complex impedance.
Sub-topics (6)
Sinusoidal Waveforms
Amplitude, frequency, period, phase, RMS and average values of a sine wave.
Phasors
Represent a sinusoid as a rotating vector with magnitude and angle, turning calculus into complex arithmetic.
Impedance and Reactance
Impedance Z = R + jX extends Ohm's law to AC; inductors and capacitors have frequency-dependent reactance.
Series and Parallel RLC Circuits
Combine resistors, inductors and capacitors in AC circuits and find total impedance and phase.
Resonance
At resonance inductive and capacitive reactances cancel — the basis of tuned circuits and filters.
AC Power
Real, reactive and apparent power — the power triangle and why power factor matters.
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