AC Circuits

Series RC Circuit

Resistance and capacitive reactance.

In the circuit of figure above, a capacitor and a resistor are shown in series. The current is calculated

The reactive component of the circuit of figure above is capacitive, so the current can be expected to lead the applied voltage by some angle. As shown by the phasor calculation, the angle of lead is 53.1°. The phase relation of applied voltage V and the current is illustrated in the figure below.

Phasors of the series RC circuit.

Calculating V_R and V_C,

Applied voltage V must be the phasor sum of V_R and V_C:

Plotting V_R and V_C on the complex plane of figure above shows that V_R and I are in phase, and that I leads V_C by 90°.