从推导点电荷的电势公式着手,进一步推导出导体球接触带电过程中电荷分配与其半径的关系,说明电荷分配的内在规律,从而解释学生的疑惑,解决教学中遇到的难点问题。 From the deduction of electric potential formula of point charge, the relation between charge distribution and radius of conductor ball during contact charging process is further deduced. The inner regularity of charge distribution is explained, which explains the students’ doubts and solves the difficult problems encountered in teaching.