Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Electrostatic Forces acting on Point Charges in the Present of a
  Dielectric Slab   How will the electrostatic interaction between two point charges change if we
introduce a dielectric slab in the middle of them? While the physical setting
of this problem is relatively simple, it is easy to be wronged and the solution
is surprisingly complicated. Here we will show the correct answer by using the
method of images, which should be approachable for undergraduate students and
advance high school students. We also obtain analytical and algebraic results
in some special cases.

36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom