电气电子教学学报
電氣電子教學學報
전기전자교학학보
Journal of Electrical & Electronic Education
2015年
5期
46-48
,共3页
时变电场%磁场%电荷弛豫%导电媒质
時變電場%磁場%電荷弛豫%導電媒質
시변전장%자장%전하이예%도전매질
time-varying electric field%magnetic field%charge relaxation%conductive medium
一般而言,时变场情况下电场和磁场是相互作用且同时存在的。依据电磁感应定律,容易理解无电场伴随的纯粹时变磁场是不存在。然而,本文强调,纯粹的时变电场是可以存在的。例如,在导电媒质的电荷弛豫过程中,如果传导电流与位移电流正好处处相互抵消,则此时可以不出现磁场。在这种场中,没有电磁能量的流动,空间储存的电场能量就地通过欧姆损耗转化为热能。
一般而言,時變場情況下電場和磁場是相互作用且同時存在的。依據電磁感應定律,容易理解無電場伴隨的純粹時變磁場是不存在。然而,本文彊調,純粹的時變電場是可以存在的。例如,在導電媒質的電荷弛豫過程中,如果傳導電流與位移電流正好處處相互牴消,則此時可以不齣現磁場。在這種場中,沒有電磁能量的流動,空間儲存的電場能量就地通過歐姆損耗轉化為熱能。
일반이언,시변장정황하전장화자장시상호작용차동시존재적。의거전자감응정률,용역리해무전장반수적순수시변자장시불존재。연이,본문강조,순수적시변전장시가이존재적。례여,재도전매질적전하이예과정중,여과전도전류여위이전류정호처처상호저소,칙차시가이불출현자장。재저충장중,몰유전자능량적류동,공간저존적전장능량취지통과구모손모전화위열능。
Generally speaking,in the case of time-varying field,both electric field and magnetic field components interact with each other and exist simultaneously. It is easy to understand that pure time-varying magnetic field may not exist according to Faradayˊs electromagnetic induction law. However,on the other hand,we show that pure time-varying electric field may exist in some cases. For example,in the process of electric charge relaxation in con-ductive medium,if both the conduction current and the displacement current cancel each other out completely, then the magnetic field component does not exist. For this case,there is no electromagnetic energy flow,and the e-lectric field energy stored in space is transferred completely into thermal energy locally by the Ohm loss mechanism.