Multiple Point Charges

The electric potential (voltage) at any point in space produced by any number of point charges can be calculated from the point charge expression by simple addition since voltage is a scalar quantity. The potential from a continuous charge distribution can be obtained by summing the contributions from each point in the source charge.

The calculation of potential is inherently simpler than the vector sum required to calculate the electric field.

The electric field outside a spherically symmetric charge distribution is identical to that of a point charge as can be shown by Gauss' Law. So the potential outside a spherical charge distribution is identical to that of a point charge. 在球对称的电荷分布外，电场与点电荷的电场相同，这可通过高斯定律证明。因此，球形电荷分布外的电势与点电荷的电势相同。

Multiple Point Charges

The electric field from multiple point charges can be obtained by taking the vector sum of the electric fields of the individual charges.

Multiple Point Charges

The electric field from multiple point charges can be obtained by taking the vector sum of the electric fields of the individual charges.

After calculating the individual point charge fields, their components must be found and added to form the components of the resultant field. The resultant electric field can then be put into polar form. Care must be taken to establish the correct quadrant for the angle because of ambiguities in the arctangent. 在计算各个点电荷的电场后，必须找到它们的分量并相加以形成 resultant 场的分量。 resultant 电场可以然后转换为极坐标形式。必须注意确定角度的正确象限，因为反正切函数存在歧义。