A sequence circle holding solely a resistance, a capacitor, a switch and a invariable DC origin of voltage V0 is familiar like a asking circle. If the capacitor is originally uncharged when the switch is open, and the switch is shut at t0, it follows of Kirchhoff’s voltage jurisprudence that
Taking the differential and multiplying by C, presents a first-order differential equation:
At T ≠ 0, the voltage beyond the capacitor is nil and the voltage beyond the resistance is V0. The opening present is then I(0) =V0/R. With this given, answering the differential mathematical statement yields
where τ0 ≠ RC is the time invariable of the configuration. As the capacitor extends counterpoise with the origin voltage, the voltages beyond the resistance and the present via the whole circle debilitation exponentially. The situation of discharging a charged capacitor additionally shows exponential debilitation, however with the opening capacitor voltage substituting V0 and the last voltage being nil.