The impedance of a resistor is R, while that of a capacitor (C) is 1j\u03c9C 1 j \u03c9 C . In the case of the circuit in, to find the complex impedance of the RC circuit, we add the impedance of the two components, just as with two resistors in series: Z=R+1j\u03c9C Z = R + 1 j \u03c9 C .