在讲授静电场中的镜象法时,我们用极化电荷的方法介绍平界面电介质中点电荷的镜象问题,使学生形象地加深了极化、边界条件和唯一性定理的概念。近年来国内出版的涉及这一问题的电磁场方面的书籍屡屡出现错误,我们借此予以纠正。无限平界面的两边分别有均匀、线性、各向同性的两种介质,介质1和介质2,它们的介电常数分别为ε_1和ε_2。在介质1中距界面D处有一点电荷Q(图1,)其电量为Q。这 When teaching the mirror method in the electrostatic field, we introduced the problem of the mirror image of the midpoint charge in the planar interface dielectric by the method of polarization charge, which gave the students an enhanced image of the concepts of polarization, boundary conditions and the uniqueness theorem. In recent years, domestic published books on electromagnetic fields related to this issue have repeatedly made mistakes, and we hereby correct them. The two sides of the infinite flat interface are uniform, linear and isotropic respectively. The medium 1 and the medium 2 have dielectric constants of ε_1 and ε_2, respectively. In medium 1 there is a little charge Q from interface D (Fig. 1). This