▁and ▁ ▁is ▁a ▁parameters ▁that ▁depends ▁on ▁the ▁material , ▁structure ▁and ▁technology ▁of ▁the ▁device . ▁ ▁Ext ensions ▁ ▁Elect romagnet ic ▁field ▁ ▁The ▁shown ▁electro kin et ics ▁theorem ▁holds ▁true ▁in ▁the ▁' qu asi ▁electro static ' ▁condition , ▁that ▁is ▁when ▁the ▁vector ▁potential ▁can ▁be ▁neglect ed ▁or , ▁in ▁other ▁terms , ▁when ▁the ▁squ ared ▁maximum ▁size ▁of ▁ ▁is ▁much ▁smaller ▁than ▁the ▁squ ared ▁minimum ▁w avel ength ▁of ▁the ▁elect romagnet ic ▁field ▁in ▁the ▁device . ▁However ▁it ▁can ▁be ▁extended ▁to ▁the ▁elect romagnet ic ▁field ▁in ▁a ▁general ▁form . ▁In ▁this ▁general ▁case , ▁by ▁means ▁of ▁the ▁disp lacement ▁current ▁across ▁the ▁surface ▁ ▁it ▁is ▁possible , ▁for ▁instance , ▁to ▁evaluate ▁the ▁elect romagnet ic ▁field ▁radiation ▁from ▁an ▁anten na . ▁It ▁holds ▁true ▁also ▁when ▁the ▁electric ▁perm itt ivity ▁and ▁the ▁magnetic ▁per me ability ▁depend ▁on ▁the ▁frequency . ▁Moreover , ▁the ▁field ▁ ▁other ▁than ▁the ▁electric ▁field ▁in ▁' qu asi ▁electro static ' ▁conditions , ▁can ▁be ▁any ▁other ▁physical ▁ir rot ational ▁field . ▁ ▁Quant um ▁mechan ics ▁ ▁Finally , ▁the ▁electro kin et ics ▁theorem ▁holds ▁true ▁in ▁the ▁classical ▁mechan ics ▁limit , ▁because ▁it ▁requires ▁the ▁simultane ous ▁knowledge ▁of ▁the ▁position ▁and ▁velocity ▁of ▁the ▁car rier , ▁that ▁is , ▁as ▁a ▁result ▁of ▁the ▁uncertainty ▁principle , ▁when ▁its ▁wave ▁function ▁is ▁essentially ▁non ▁null ▁in