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设想一种模型:电流从a点流至b点,且保持恒定,则在a、b分别堆积起等量异号之电荷,此时空间各点的电场在变化,而磁场则稳定。于是从Biot-Savart定律可导出: 任何场都可认为是有源无旋场(纵场)和有旋无源场(横场)的迭加。对应于可变有源无旋电场的位移电流不激发磁场。电磁波的激发和传播取决于有旋无源电场的位移电流。我们通常所说的电容器中的位移电流就是对应于可变有源无旋电场的位移电流。若把电场和磁场都可变的普遍情况下的Maxwell方程作为此模型 (1) 式的自然推广,则不必引进位移电流的概念。最后,文中论述了电磁场理论的逻辑结构。
Imagine a model where the current flows from point a to point b and stays constant, then an equal number of charges are accumulated in a and b, respectively. At this point, the electric field at each point in space changes and the magnetic field is stable. From Biot-Savart’s law, we can derive that any field can be considered as a superposition of active and non-rotating fields (longitudinal fields) and gyrotically passive fields (horizontal fields). The displacement current corresponding to the variable active gyro-electric field does not excite the magnetic field. The excitation and propagation of electromagnetic waves depend on the displacement current of a rotating passive field. We usually say that the displacement current in the capacitor is the displacement current corresponding to the variable active gyro-electric field. If the generalized Maxwell equation where both electric and magnetic fields are variable is used as a natural extension of this model (1), there is no need to introduce the notion of displacement current. Finally, the article discusses the logical structure of electromagnetic field theory.