The symbol for that is z and the unit for impedance is ohm. Reactance is a more straightforward value. Ac Capacitance And Capacitive Reactance In Ac Circuit Source Transformation With Impedance Being Inductor Or Ec Formula Impedance Z vi rms voltage rms current. Equation for impedance of a capacitor . The capacitance impedance calculator calculates the impedance of a capacitor based on the value of the capacitance c of the capacitor and the frequency f of the signal passing through the capacitor according to the formula x c 12pfc. Unless otherwise specified the source voltage will be our reference for phase shift and so will be written at an angle of 00. The above equation gives you the reactance of a capacitor. To calculate impedance you must know the value of all resistors and the impedance of all inductors and capacitors which offer varying...