The next formula are used in calculations involving the impedance of an RC parallel circuit.
Formula 1
Where:
Z is the impedance in ohm (Ω)
R is the resistance in ohm (Ω)
Xc is the capacitive reactance in ohm (Ω)
(See the formula for Capacitive Reactance)
In the vectorial representation we defined two new important quantities:
Y (the inverse of impedance) is named “admitance” and is measured in siemens (S).
G (the inverse of resistance) is named “conductance” and is expressed in siemsns (S)
Sc (the inverse of reactance) is named “susceptance” in is measured in siemens (S).
Application Example
Calculate the impedance of a capacitor and a resistor wired in parallel. As given, the capacitor reactance of the capacitor is 20 Ω and the resistance is 10 Ω.
Data:
R = 10 Ω
Xc = 20 Ω
Applying formula 1:
