5  POTENTIAL DUE TO A SYSTEM OF CHARGES
Consider a system of charges q1, q2,…, qn with position vectors r1, r2,…,
rn relative to some origin (Fig 2 6) The potential V1 at P due to the charge
q1 is
1
1
0
1P
1
4
q
V
εr
=
π
where r1P is the distance between q1 and P