§2.1 静电场的标势及其微分方程 Scalar potential and differential equation for electrostatic field §2.2 唯一性定理 Uniqueness theorem §2.3 拉普拉斯方程,分离变量法 Laplace's equation, method of separate variation §2.4 镜象法 Method of images §2.5 格林函数法 Method of Green function §2.6 电多极矩 Electric multipole moment