The electrostatic field magnitude can play a role in a variational principle similar to the role of the index of refraction in geometrical optics, allowing the determination of electric field lines. This was identified in the context of the grounded conducting sphere image problem. Assuming the knowledge of the magnitude of the electric field, in this paper, we validate this principle for the general case and explore some of its consequences.

1.
Herbert
Goldstein
,
Classical Mechanics
(
Pearson Education India
,
Chennai
,
2011
).
2.
Lev Davidovich
Landau
,
The Classical Theory of Fields
(
Elsevier
,
New York
,
2013
), Vol.
2
.
3.
John David
Jackson
,
Classical Electrodynamics
, 3rd ed (
Wiley
,
New York
,
1999
).
4.
Kolahal
Bhattacharya
, “
Analogy of the grounded conducting sphere image problem with mirror optics
,”
Eur. J. Phys.
32
(
5
),
1163
1170
(
2011
).
5.
Kolahal
Bhattacharya
, “
A novel variational principle in electrostatics and its consequences
,”
J. Electrostat.
71
(
5
),
926
930
(
2013
).
6.
Kolahal
Bhattacharya
, “
Demystifying the nonlocality problem in Aharonov-Bohm effect
,”
Phys. Scr.
96
,
08411
(
2021
).
7.
James
Evans
and
Mark
Rosenquist
, “
F = ma optics
,”
Am. J. Phys.
54
(
10
),
876
883
(
1986
).
8.
Max
Born
and
Emil
Wolf
,
Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light
, 7th ed. (
Elsevier
,
New York
,
2013
).
9.
Kolahal
Bhattacharya
, “
On the dependence of charge density on surface curvature of an isolated conductor
,”
Phys. Scr.
91
(
3
),
035501
(
2016
).
10.
J.
Warren Blaker
and
Morton A.
Tavel
, “
The application of Noether's theorem to optical systems
,”
Am. J. Phys.
42
(
10
),
857
861
(
1974
).
11.
Ezzat G.
Bakhoum
, “
Proof of Thomson's theorem of electrostatics
,”
J. Electrost.
66
(
11–12
),
561
563
(
2008
).
12.
G. A.
Estevez
and
L. B.
Bhuiyan
, “
Power series expansion solution to a classical problem in electrostatics
,”
Am. J. Phys.
53
(
2
),
133
134
(
1985
).
13.
Richard C.
Pappas
, “
Differential-geometric solution of a problem in electrostatics
,”
SIAM Rev.
28
(
2
),
225
227
(
1986
).
14.
Constantine
Pozrikidis
,
Fluid Dynamics: Theory, Computation, and Numerical Simulation
(
Springer
,
New York
,
2016
).
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.