Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Laws of Electromagnetic Induction   The Faraday-Ampere laws of electro-magnetic induction are formulated in terms
of plain and twisted differential forms, taking in due account the body motion
in terms of Lie time-derivatives. Covariance of Lie derivatives with respect to
arbitrary relative motions, and Galilei invariance of the electro-magnetic
fields, imply Galilei invariance of the induction laws, contrary to most claims
in literature. A noteworthy outcome of the theory is the conclusion that the so
called Lorentz force on a charged particle is not an additional law of
electromagnetism, but rather, when corrected by a factor one-half, a
contribution to the electric field evaluated, according to Faraday law, by an
observer testing a translating charged body crossing a region of uniform
magnetic field. The formulation of the laws of electromagnetism in the four
dimensional classical space-time, by stating the observer-dependent splitting
for bodies in motions, provides a proof of Galilei invariance of all the
electric and magnetic fields involved in the analysis.

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The categories of this paper are: econ
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph