只要把 P 和 M 两块平板换成 yz 平面的一块平板, 平板上有 y 方向的振荡面电流密度 (surface current density), 就可以向 +x 与 -x 方向发射平面电磁波了. 如果一定要给定一个零时刻, 那也没有关系.
2
?电流面密度
...密度(surface Charge Density)电荷线密度(Linear Charge Density)电流密度(Current Density)电流面密度(surface Current Density)电能密度(Electric Energy Density)电通量(Electric Flux)电通量密度(Electric Flux Density)磁能密度(Magnetic Energy Density)...
Besides the authors advance a new calculation method that volume currentdensity caused by saturation, medium is turned into equivalent surfacecurrentdensity.
提出了将媒质中由饱和引起的体电流密度化为等效面电流密度的计算方法。
2
The measuring methods of D C TIG welding arc anode sheet surfacecurrentdensity split sheet method and probe (made by ourselves) method were analysed and compared.
对直流TIG电弧阳极板表面电流密度的测量方法——分离极板法和探针（自制）法进行了分析比较。
3
In the simplest setup, the size of the current reveals the density of electrons in the surface, allowing it to be mapped out.