沿导线长度存在梯度恒定的表面电荷分布，并在整个导线长度上产生恒定的电场。这导致在导线的所有部分都有恒定的电流。
我知道平衡时表面电荷的分布是恒定的，但当电路完成时，分布不是恒定的，但表面电荷密度的变化是恒定的。
有人能给我解释一下，这个恒定的表面电荷梯度是如何形成的吗?我想知道从平衡(开路)到稳态(闭合)的整个过程的表面电荷再分配
但是为了完整的描述，我们确实应该使用带有动画场图的FEM有限元模拟器，因为导线中的每个带电体都将经历到遥远地球的电容……并且对导线中每一个带电体积都显示出一个电容!< / p > < p >的一个方法是最初假设导线电阻为零,并且可以建模为薄空心管(纯集肤效应,所有瞬态和没有长期直流。)< / p > < p >当电压降是第一次应用于细长的导体,电磁波舞蹈沿着这来回空心管,制造电荷环并推动它们，直到它们稳定下来并在表面产生均匀的电流密度。这是以光速发生的，超过几分之一纳秒。嗯，与其在太空中寻找一根导线，不如先检查一根同轴电缆的中心导体，这样也许会简化事情。这样，电阻器就变成了一条简单的传输线，所有的电容只存在于导线表面和屏蔽编织层附近的内表面之间。在这种情况下，导线变成了一个非常非常长的电感，就像一个很长的线圈，但在导线表面和附近的地电势之间连接着许多电容器。
Then, once we know the nanosecond behavior of voltage-waves on this conductor, then for real conductors having finite resistance, next the current "oozes inside" over long microseconds. All metals are EM-shields of course, so the initial e-fields and currents are blocked from affecting the interior of the metal wire. The elements of the wire exhibit L/R time constants, with slower response for lower resistance. Or in other words, charge "has inertia," and the applied e-field can only, after a significant delay, create a current within the interior of the wire.
Or said differently, the speed of light inside copper is quite slow, on the order of tens of M/S, and "skin effect" is really about the electrical energy being able to "leapfrog" quickly across the space outside the metal surface, and only slowly to propagate inwards ...as if the wire was really an "onion layer" of concentric pipes. At first, the entire current only arises on the outside pipe. For a thick copper wire, an entire millisecond may pass by before the current becomes uniform throughout the metal. Yet the first initial current-pattern became established millions of times faster, in roughly a nanosecond.
See, we really really need animated diagrams!
But so few people are interested in this niche-topic, such things have never been done before. And with good reason. At MIT, a Dr. Belcher tried to introduce it to thir large undergrad EM course, with field-simulations giving a view of the internal workings of all components. Rumor is, the undergrad students rose up en masse and forced the administration to go back to the old way: obscure walls of equations, with none of these easily-understood animated pictures! To me the situation appears like that of medical doctors in the year 1300, if their med school suddenly started teaching courses in plain English (or French!) Nooooo! Then just anyone could understand the material! It turns the complex and obscure into "Physics for Poets!" BRING BACK THE LATIN RIGHT DAMN QUICK, OR THE STUDENT BODY WILL MARCH IN AND HANG THE LOT OF YOU!
Heh.
Here's the residue of the late-1990s MIT "T.E.A.L" project by JW Belcher and crew...