Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A formal interpretation of the displacement current and the
  instantaneous formulation of Maxwell's equations   Maxwell's displacement current has been the subject of controversy for more
than a century. Questions on whether the displacement current represents a true
current like the conduction current and whether it produces a magnetic field
have recently been discussed in the literature. Similar interpretations for the
Faraday induction current have also been controversial. These basic questions
are answered in this paper by considering the relation between the displacement
and conduction currents as well as the relation between Faraday induction and
conduction currents. It is pointed out that the displacement current
contributes to the magnetic field and that the induction current contributes to
the electric field. However, the displacement and induction currents cannot be
considered as the conduction current because they are nonlocal. Both relations
are used to implement an instantaneous formulation of Maxwell's equations with
local and nonlocal sources.

36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph