The capacitor is used to store the charge applied to it.   This stored charge can be used to absorb voltage spikes and voltage  drops.   Answer   It's a misconcep … tion that a capacitor stores charge. In fact, it  stores energy.ue to the charging of capaitor with the rise in voltage and discharging of capacitor with the fall, the change voltage across it (which is also the ouput voltage of the recti … fier) is gradual and not abrupt.