Electrical Engineering ⇒ Topic : A.C. Circuit Containing Capacitance Only

When an alternating voltage is applied across the plates of a capacitor, the capacitor is charged in one direction and then in the other as the voltage reverses. The result is that electrons move to and fro around the circuit, connecting the plates, thus constituting alternating current.

                                                                (a)                                                                                (b)

                                                                                               figure

Consider an alternating voltage applied to a capacitor of capacitance C farad as shown in Fig. (a). Let the equation of the applied alternating voltage be

                                                                                                 v = V_m sin ωt                                              ...(i)

As a result of this alternating voltage, alternating current will flow through the circuit. Let at any instant i be the current and q be the charge on the plates.