Thus,
2
2
0
0
4
4
q
q
r
r
φ
ε
ε
=
×
π
=
π
(1 30)
Equation (1 30) is a simple illustration of a general result of
electrostatics called Gauss’s law We state Gauss’s law without proof:
Electric flux through a closed surface S
= q/e0
(1