Maxwell's equations conserve certain properties-the magnetic field intensity, the electric displacement field and the Poynting vector that describes the electric flux of an electromagneticfield.
麦克斯韦方程中有某些特性是恒定不变的——磁场强度、电位移场以及描述电磁场电通量的坡印廷矢量。
2
Patients undergoing this treatment have a coil placed on their head which uses electromagnetic induction to activate weak electric currents via a changing magnetic field.
进行该项治疗的患者在头部置有一个线圈，这个线圈通过电磁感应在一个变化的磁场中激活弱电流。
3
Although the description of the system involves the electromagnetic potential, the physical properties only depend on the electric and magnetic field-strength.