Serial RC Circuit
A serial RC circuit contains a resistor and a capacitor connected in serial.
The alternating voltage U is applied to the circuit, so the alternating current is flowing through the branch:
The resistor's voltage:
The capacitor's voltage lags behind the current by phase angle π/2:
where XC = 1/ω·C - capacitive resistance.
The vector diagram for all voltages (voltage triangle):
After we divide all voltages by current I, we get the resistance triangle:
where R - the active resistance, XC - the capacitive resistance, Z - the total resistance (or impedance). The total resistance is:
The total voltage lags behind current by phase angle φ:
The angle goes in clockwise direction (from current vector to voltage vector), hence it is negative here.
The power coefficient is defined as an active and reactive resistance ratio:
The effective current I, flowing through the circuit:
The active power:
The reactive power:
The total power: