Inductors in AC Circuits Previously, a procedure was discussed for working with circuits containing resistors and capacitors driven by sinusoidal alternating current sources. Essentially, all circuit elements were converted to phasors, math was carefully done on these complex values, and the results were converted back to the time domain. Generically, voltages and currents of the form Atrig(ωt + φ)became A∠φwhere Awas the amplitude, φwas the phase shift, and trigwas either sinor cos. A resistance simply became !R=R!0°. A capacitance became a kind of reactance: !X=!1"C#90°. Inductances also become reactances. The value is given by !X=!L"90°. Recall that phasors can be directly added only if they have the same angle. The only significant difference between capacitive and inductive reactances is that one kind is negative and the other is positive. Capacitors act like open circuitswhen connected to DC. This is because there is no physical connection between the plates. For AC, as the frequency ω
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