InDCcircuits,capacitorsareequivalenttoopencircuits.Capacitorsareoneofthemostcommonlyusedelectroniccomponentstostorecharge.Thisbeginswiththestructureofthecapacitor.Thesimplestcapacitorsaremadeupofpolarplatesatbothendsandinsulatingdielectric(includingair)atthemiddle.Afterelectrification,theplateischarged,formingavoltage(potentialdifference),butbecauseoftheintermediateinsulation,theentirecapacitorisnon-conductive.However,insuchacasethecriticalvoltage(breakdownvoltage)doesnotexceedthecapacitor.)