从《力学》角度分析《电磁学》中的自由度

摘要

本文从《力学》角度讨论《电磁学》中一些客体的自由度以深化教学、提高学生正确分析物理问题的能力。使用实际教学分析的研究方法，先介绍《力学》中自由度特点，接着切入分析《电磁学》中一些客体的自由度并得出以下结论：(1)单个无、有极分子在无或有外电场时其自由度均为3；（2）无外电场时：由无、有极分子构成的刚性电介质有6个自由度，构成的非刚性电介质除反映整体运动的6个自由度外其内部还有3N-6个振动自由度；有外电场时：由无、有极分子构成的电介质整体的自由度为3（不考虑内部振动和干扰因素时）；（3）平面偏振光的光矢量有3个自由度。然后分析《电磁学》里电磁波中某时刻某点平面偏振光与自然光振动矢量的自由度，最后讨论场的自由度及研究《力、电磁学》中自由度的意义。%The degree of freedom of some bodies of electromagnetics is talked in order to deepen teaching and enhance students ability to correctly analyze physical problem in this paper. Firstly, the characters of the degree of freedom of mechanics are introduced.Then the degree of freedom of some bodies of electromagnetics is analyzed by the approach of actual teaching and analyse .The conclusions are as fol owing:(1)The degree of freedom of single non-polar (or polar molecule) is 3 having electric field or not.(2)The degree of freedom of rigidity dielectric medium being made up of non-polar or polar molecules is 6,but the nonrigidity dielectric medium being made up of them has 3N-6 vibrating degrees of freedom except for the 6 degrees of freedom that embody the whole dielectric medium’s movement without electric field.The degree of freedom of dielectric medium being made up of non–polar or polar molecule is 3 having electric field(withou inner vibrating and disturb-ing factors). (3) The degree of freedom of the vector of plane polarized light is 3. The degree of freedom of vibrating vector of plane polarized light and natural daylight at sometime and somespot is analyzed in the field of electromagnetic wave in electromagnetics. Final y, the degree of freedom of electric and magnetic field is talked and the studying significace of the degree of freedom of electromagnetics of university physics is showed.