The electric potential at a point due to a system of point charges is equal to the algebraic sum of potentials due to all individual charges of the system at that point.
Consider a system of charges q1, q2,…, qn with position vectors r1, r2,…,rn relative to some origin. The potential V1 at P due to the charge q1, the potential V2 at P due to q2 and Vn due to qn are given by
By the superposition principle,
V = V1 + V2 + ...Vn