rn, the potential at a point P is given by the superposition principle
1
2
0
1P
2P
P
1
( )
4
n
n
q
q
q
V
r
r
r
ε
=
+
+
+
π
where r1P is the distance between q1 and P, as and so on 5 An equipotential surface is a surface over which potential has a constant
value