Question

What is the reactance of a capacitor connected to a constant DC source?

Answer 1

Reactance of a capacitor is given by X_c = 1/(2*pie*freq* C), where C is the capacitance of a capacitor.

For dc, frequency is zero, so reactance of the capacitor would become infinite.. hence Capacitoss are used for AC coupling (DC blocking) . But in the transient state , they do allow some DC current to flow through them till they achieve saturation . This is given by what are known as Helmholtz equations