从加速运动介质中的法拉第电磁感应定律到拓展的麦克斯韦方程组  

From Faraday’s law to the expanded Maxwell’s equations for a mechano-driven media system that moves with acceleration

作　　者：王中林[1,2,3] 邵佳佳 WANG ZhongLin;SHAO JiaJia(Beijing Institute of Nanoenergy and Nanosystems,Chinese Academy of Sciences,Beijing 101400,China;School of Nanoscience and Technology,University of Chinese Academy of Sciences,Beijing 100049,China;School of Materials Science and Engineering,Georgia Institute of Technology,Atlanta 30332,USA)

机构地区：[1]中国科学院北京纳米能源与系统研究所,北京101400 [2]中国科学院大学纳米科学与技术学院,北京100049 [3]佐治亚理工学院材料科学与工程学院,美国亚特兰大30332

出　　处：《中国科学：技术科学》2023年第3期430-444,共15页Scientia Sinica(Technologica)

摘　　要：在经典电动力学中,无论相对运动的是观察者或是有几何形状的介质,一般教材中默认它们进行匀速直线运动(即惯性参考系);所以,狭义相对论(洛伦兹变换)可以方便地描述真空中带电粒子的电磁场变化规律.在工程应用中,介质一般有不同的形状和大小,更多情况下进行的是加速运动.最近有关运动介质的纳米发电机实验表明,为描述工程中带电介质变速运动时的电磁场动力学变化规律,有必要对麦克斯韦方程组进行拓展.因此,对于低速运动介质且在忽略相对论效应的情况下,我们系统地构建了研究加速运动介质电磁现象的动生麦克斯韦方程组.本文首先概括了动生麦克斯韦方程组的最新研究进展,接着深入探讨加速运动介质系统中的法拉第电磁感应定律.我们发现:费曼物理讲义中列举的“反通量法则”的例子正是由于不可忽略几何形状的介质的运动引起,描述介质加速运动的(v_(r)×B)项没有被包含在经典的麦克斯韦方程组关于电磁感应定律的表达式中.这是拓展麦克斯韦方程组的一个典型例证.所以,介质运动是产生电磁波的源之一(动生电);对于一个不可忽略几何尺寸和体积的介质,无论其是否有加速度,描述介质内部的电动力学现象使用动生麦克斯韦方程组.另外,动生麦克斯韦方程组把传统的电磁发电机理论与描述电磁波的麦克斯韦方程组两种不同情况有机结合并统一描述出来.最后,对动生麦克斯韦方程组和经典麦克斯韦方程组之间的四个主要区别进行了总结,提出了近场电动力学与远场电动力学的相关概念.In classical electrodynamics,by motion for either the observer or the media,it always naturally assumed that the relative moving velocity is a constant along a straight line(e.g.,in an inertia reference frame),so that the electromagnetic behavior of charged particles in vacuum space can be easily described using special relativity.However,for engineering applications,the media have shapes and sizes and may move with acceleration,and recent experimental signs of progress in triboelectric nanogenerators have revealed pieces of evidence for expanding Maxwell’s equations to include media motion that could be time and even space dependent.Therefore,we have developed the expanded Maxwell’s equations for a mechano-driven media system(MEs-f-MDMS)by neglecting relativistic effect.This article first presents the updated progresses made in the field.Secondly,we extensively investigated Faraday’s law of electromagnetic induction for a media system that moves with an acceleration.We found that,the“anti-flux rule”examples outlined by Feynman in his book are just caused by the accelerated motion of the media,which were not included in Maxwell’s equations,but disregarded.This is a typical example that Maxwell’s equations have to be expanded for moving media.Therefore,the charged moving media are confirmed to be the sources of generating electromagnetic radiation(a motion-generated electromagnetic field);and the generated electromagnetic wave within the medium can be described using the expanded Maxwell’s equations.Most importantly,in comparison to the existing classical electrodynamics,the newly developed MEs-f-MDMS marks four unique advances,which have been summarized and the near field electrodynamics vs.the far field electrodynamics are proposed.

关 键 词：动生麦克斯韦方程组 法拉第电磁感应定律 非惯性参考系 费曼的“反通量法则”例子 

分 类 号：O441[理学—电磁学]