 Capacitive reactance formula_2 is inversely proportional to the signal frequency formula_3 (or angular frequency ω) and the capacitance formula_4.There are two choices in the literature for defining reactance for a capacitor.One is to use a uniform notion of reactance as the imaginary part of impedance, in which case the reactance of a capacitor is the negative number,

Another choice is to define capacitive reactance as a positive number,

In this case however one needs to remember to add a negative sign for the impedance of a capacitor, i.e.