Question

Explain why current flows through an ideal capacitor when it is connected to an a.C. Source but not when it is connected to a d.C. Source in steady state

Answer 1

If an ideal capacitor is charged by DC battery, current flows momentarily till capacitor gets fully charged after that no current flows, however when an AC source is connected, then conduction current

${ I}_{ c }$ = dq/dt

starts flowing in the connecting wire. As charging polarity of AC current changes, the capacitor is alternatively charged and discharged with time. This causes change in electric field between plates of the capacitor which causes electric flux to change and gives rise to displacement current in the region between plates of capacitor as displacement current.