电偶极子与单摆

An electric dipole and a mechanical pendulum

电偶极子是电磁学基本模型之一,其电场强度分布颇有特点.通常教材要么给出电势然后做梯度计算,要么通过矢量叠加直接给出场强,推导比较数学化,学生难以对偶极子场强特点和物理图像获得直观理解.本文把熟知的力学单摆和偶极子联系起来,通过力电类比给出偶极子电场的两种形式,特别是不依赖坐标的场强形式,清楚阐明了各分量特点,还给出类比方法的应用实例.这种方法有助于初学者从不同角度体会知识点联系,深入理解偶极子物理图像,强化类比思维.

The electric dipole,as one of the basic models of electromagnetism,has an exotic field distribution,which in the normal textbooks is given by either the gradient of the electric potential or the vector superposition method.These mathematical approaches are hardly helpful for students to understand the features and the unique picture of the dipole field distribution.Here,based on an analog of the mechanical pendulum and the electric dipole,we give the two forms of the dipole field,especially the free-of-coordinate one,and practical applications of this analog.Our paper can benefit beginners in seeing the inner relation of knowledges,understanding the features of the dipole,and appreciating the power of analogy thinking.