So far we have considered the potential due to point charges only. As any other type of charge distribution can be considered to be consisting of point charges, the same basic ideas now can be extended to other types of charge distribution also.
Let us first consider N point charges Q₁, Q₂,.....Q_N located at points with position vectors ,,....... The potential at a point having position vector can be written as:

..................................(2.30a)

or, ...........................................................(2.30b)

For continuous charge distribution, we replace point charges Q_n by corresponding charge elements or or depending on whether the charge distribution is linear, surface or a volume charge distribution and the summation is replaced by an integral. With these modifications we can write:

For line charge, ..................................(2.31)