摘要
为清晰、透彻地理解静电学中涉及的各种能量的基本概念,本文从场的观点和电荷的观点分析讨论了该问题,并选择了几个熟悉的例子来说明本文认识的合理性.依照场的观点,真空中两个体积足够小的电荷的静电场能量密度为:1/2ε0E21+1/2ε0E22+ε0E1·E2.其中,1/2ε0E21和1/2ε0E22分别为两个电荷单独存在时的电场能量密度,而交叉项ε0E1·E2则为两个电荷电场的相互作用能量密度;它们的空间积分分别为两个电荷单独存在时的静电场能量和两个电荷电场之间的相互作用能量.而从电荷观点出发,此3个静电场的能量分别为两个电荷的固有能和彼此之间的静电相互作用势能.推广到有限体积的孤立带电导体以及带电导体系的情形,可知孤立带电导体的固有能就是其上所有无限小电荷元间的相互作用势能之和,而带电导体系的电场能也就是体系所包含的所有电荷元间的相互作用势能的总和.
Different energies involved in electrostatics are discussed based on the electric field and charge. Accordingly, the related basic concepts could be understood more thoroughly and clearly. It has been shown that the energy of the electrostatic field of two changes, each of which has small volume, could be expressed either as the integral of the density of field energy with the point of view of electric field or as the sum of the intrinsic energies of these two indi- vidual charges and the electric potential energy between them. Then the intrinsic energy of an isolated changed conductor could be shown as just the sum of the electric potential energies be- tween any pair of infinitesimal charge elements on the conductor. Also the total energy of the electric field of a system consisting of charged conductors could also be shown as just the sum of the electric potential energies among all the infinitesimal charge elements within the sys- tem. Several familiar examples are selected to show the reasonability of the present under- standing.
出处
《物理与工程》
2015年第3期34-37,共4页
Physics and Engineering
关键词
电场能
电势能
固有能
energy of electric field
electric potential energy
intrinsic energy
作者简介
冀敏，女，副教授，主要从事物理教学与研究，科研方向为医学物理．jimin01@fudan．edu．cn
通讯作者：蒋平，男，教授，主要从事物理教学与研究，科研方向为凝聚态物理．
