arXiv subjects

Bernard Jancewicz

Publications and source records attributed to Bernard Jancewicz.

4 recordsLinked to original sources

arXiv2018

"Plane" electromagnetic wave in spatially flat Friedman universe

The electromagnetic theory is, to a large extend, metric independent. Before the metric is introduced, it is called premetric electrodynamics. Metric enters the constitutive relation. We consider this relation for the Friedman model of an expanding Universe and find that the magnitudes of the field quantities depend on the scale factor. This factor, however, does not enter the permeability and permittivity of the vacuum. A spatially uniform electromagnetic field is obtained for spatially flat metric. Then plane electromagnetic wave is found with uniform field playing the role of amplitudes. It turns out that the magnitudes of the frequency and the wave covector depend on the scale factor determining the redshift, but the phase velocity of the wave is constant.

gr-qc↗

arXiv2008

Premetric electrodynamics

Classical electrodynamics can be divided into two parts. In the first one, with the use of a plenty of directed quantities, namely multivectors and differential forms, no scalar product is necessary. It is called premetric electrodynamics. In this part, principal laws of the theory can be tackled, among them the two observer-independent Maxwell's equations. The second part concerns specific media and requires establishing of a scalar product and, consequently a metric. We present an axiomatic approach to electrodynamics in which the metric enters as late as possible. Also a line of research is mentioned in which the notion of non-inertial observer is studied and its influence on observer- dependent Maxwell equations.

physics.class-ph↗

arXiv2005

Plane electromagnetic wave in PEMC

Plane electromagnetic wave propagating in perfect electromagnetic conductor (PEMC) is considered. Its wave number has no connection with the frequency. An interface is introduced between an ordinary isotropic medium and PEMC. The wave in PEMC is matched to plane electromagnetic wave incident normally on the interface from the ordinary medium and reflected from it. Then the plane-parallel slab made of PEMC is considered and a plane wave is found in it.

physics.class-ph↗

arXiv1998

Answer to Question 55: Are there pictorial examples that distinguish covariant and contravariant vectors?

We present pictorial means of distinguishing contravariant vectors (or simply vectors) from covariant vectors (or linear forms). When one depicts vector as the directed segment, then the pictorial image of a linear form is a family of equidistant parallel planes with an arrow joining the neighbouring planes and showing the direction of increase of the form. First of these planes is the linear subspace of dimension two on which the linear form gives value zero. Several examples of physical quantities are given which are naturally vectors, and others which are naturally linear forms.

gr-qc↗