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18: Alternating-Current Circuits

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    • 18.1: Prelude to Alternating-Current Circuits
      Electric power is delivered to our homes by alternating current (ac) through high-voltage transmission lines. As explained in Transformers, transformers can then change the amplitude of the alternating potential difference to a more useful form. This lets us transmit power at very high voltages, minimizing resistive heating losses in the lines, and then furnish that power to homes at lower, safer voltages.
    • 18.2: AC Sources
      Most examples dealt with so far in this book, particularly those using batteries, have constant-voltage sources. Thus, once the current is established, it is constant. Direct current (dc) is the flow of electric charge in only one direction. It is the steady state of a constant-voltage circuit.
    • 18.3: Simple AC Circuits
      In this section, we study simple models of ac voltage sources connected to three circuit components: (1) a resistor, (2) a capacitor, and (3) an inductor.
    • 18.4: RLC Series Circuits with AC
      An RLC series circuit is a series combination of a resistor, capacitor, and inductor connected across an ac source.
    • 18.5: Power in an AC Circuit
      A circuit element dissipates or produces power according to P=IVP=IV , where I is the current through the element and V is the voltage across it. Since the current and the voltage both depend on time in an ac circuit, the instantaneous power is also time dependent.
    • 18.6: Resonance in an AC Circuit
      In the RLC series circuit, there is a resonant frequency where the inductive reactance equals capacitive reactance. The average power versus angular frequency plot for a RLC circuit has a peak located at the resonant frequency; the sharpness or width of the peak is known as the bandwidth. The bandwidth is related to a dimensionless quantity called the quality factor. A high quality factor value is a sharp or narrow peak.
    • 18.7: Transformers
      The device that transforms voltages from one value to another using induction is the transformer.  A transformer basically consists of two separated coils, or windings, wrapped around a soft iron core.
    • 18.8: Alternating-Current Circuits (Summary)
    • 18.9: Alternating-Current Circuits (Exercise)
    • 18.10: Alternating-Current Circuits (Answers)

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