Unformatted text preview: Capacitors, Resistors & Inductors in AC Circuits Topics of Discussion Types of Circuits Phasors RMS Voltage & Currents Resistance, Capacitance & Inductors in AC Circuits Two Types of Circuits A DC circuit or direct current circuit is a collection of electronic components whose source of voltage or current is fixed. An AC circuit or an alternating current circuit is a collection of electronic components whose source of voltage or current is varies with time. Phasors
A phasor is a rotating vector at an angular frequency which represents the instantaneous voltage V and current I of an electronic component of an AC circuit.
V I RMS Voltage & Current
Let V0 and I0 be the peak voltage and current supplied to an AC circuit. Then the rms voltage and current are given by V0 Vrms = 2 and I0 I rms = . 2 Resistance in AC Circuits
Recall that the resistance R measured in ohms () remains constant over a wide range of applied voltages Vrms and currents Irms, and is given by Ohm's Law Vrms = IrmsR. Capacitors & Capacitive Reactance The capacitive reactance C describes the impeding effects of a capacitor C on an AC
current, and is given by C 1 = 2 fC . where f is the linear frequency of the AC source. The corresponding rms voltage is given by Vrms = Irms C. Inductors & Inductive Reactance The inductive reactance L describes the impeding effects of a inductor L on an AC
current, and is given by L = 2 fL . where f is the linear frequency of the AC source. The corresponding rms voltage is given by Vrms = Irms L. Voltages & Currents in AC Circuits For resistors, the voltage and current are
in phase. For capacitors, the voltage lags the current by 90. For inductors, the voltage leads the current by 90. RCL Circuit An RCL circuit is composed of a resistor R, an
inductor L and a capacitor C attached to an emf source E . The impedance Z is the net opposition to the flow of current in an RCL circuit, and is given by 2 2 Z = R + ( L - C ) . The phase angle is given by L- C . tan = R ...
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