2  ELECTROSTATIC POTENTIAL
Consider any general static charge configuration We define
potential energy of a test charge q in terms of the work done
on the charge q This work is obviously proportional to q, since
the force at any point is qE, where E is the electric field at that
point due to the given charge configuration It is, therefore,
convenient to divide the work by the amount of charge q, so
that the resulting quantity is independent of q