Electromagnetic momentum density and the Poynting vector in static fields

1994 ◽  
Vol 62 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Francis S. Johnson ◽  
Bruce L. Cragin ◽  
R. Richard Hodges
Keyword(s):  
Poynting Vector ◽  
Momentum Density ◽  
Electromagnetic Momentum

scholarly journals Scattering forces on magneto-dielectric particles and the electromagnetic momentum density

2013 ◽  
Vol 2 (2) ◽  
pp. 26
Author(s):  
M. I. Marques ◽  
J. J. Saenz
Keyword(s):  
Poynting Vector ◽  
Momentum Density ◽  
Average Value ◽  
Dielectric Particles ◽  
Scattering Force ◽  
Electromagnetic Momentum

In this paper we analyze the non-conservative forces on  magneto-dielectric particles in special configurations where  the scattering force is not proportional to the average value  of the Poynting vector. Based on these results, we revisit  the concept of electromagnetic momentum density.

scholarly journals The motional effects of the maxwell æther-stress

1909 ◽  
Vol 83 (560) ◽  
pp. 109-119
Keyword(s):  
Continuous Medium ◽  
Poynting Vector ◽  
Present Condition ◽  
Conservation Of Energy ◽  
State Of Stress ◽  
Rate Of Increase ◽  
Electromagnetic Momentum ◽  
Energy And Momentum ◽  
Similar Element ◽  
Maxwell Stresses

There is an outstanding gap in electromagnetic theory in respect to the attempt to reconcile the analysis of æthereal stress on the lines initiated by Maxwell with Newton’s third law and the law of the conservation of energy. In the present condition of theory there is assigned to the æther a certain distribution of electromagnetic energy and momentum. The hypothetical distribution of energy is necessarily associated with the Poynting vector which measures its rate of transference. The distribution of momentum is so defined that the rate of increase of the total amount, within any given volume supposed at rest in the æther, is equivalent to the resultant of the Maxwell stresses on the bounding surface. There is, however, no connection established between the transference of energy across an area and the stress across that area. Such a connection would require that it should be possible to assign to the medium in which stress and energy reside a state of motion whereby the stresses might do the necessary amount of work, and this again would require the revision of the specification of stress, inasmuch as the ordinary expressions are computed for an element of surface which is at rest. Numerous other questions arise as soon as such a process is attempted, but the present paper seeks only to analyse what types of motion must be looked for, and to specify the field of stress upon the elements of area moving with the velocities obtained. Strictly, it is incorrect to speak of the stresses on elements of area in the æther at the same point having different velocities. The true stress in a continuous medium can only be estimated on an area moving with the medium. All that can be done in the absence of a knowledge of the velocity of the medium is to analyse the transference of momentum across an element of area having a specified velocity. Only when this velocity is that of the medium is it legitimate to interpret this transference as due to a state of stress in the medium. Thus, unless the æther is supposed at rest, the Maxwell expressions have no significance, except as giving the rate at which momentum is crossing an element of area at rest. If, however, the æther is assumed at rest, then no state of stress can give rise to any transfer of energy. 1. The flux of momentum across an element of area moving with velocity v differs from that across a similar element at rest by the vector v v g per unit area, g being the intensity of the electromagnetic momentum (=[EH]/4 πc ) and v v being the component of v normal to the area.

scholarly journals Relativistic Rotating Electromagnetic Fields

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
H. Vargas-Rodríguez ◽  
A. Gallegos ◽  
M. A. Muñiz-Torres ◽  
H. C. Rosu ◽  
P. J. Domínguez
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Fields ◽  
Symmetry Axis ◽  
Poynting Vector ◽  
Momentum Density ◽  
Axially Symmetric ◽  
Speed Of Light ◽  
Vector Form ◽  
Magnetic Dipoles ◽  
Axis Of Symmetry

In this work, we consider axially symmetric stationary electromagnetic fields in the framework of special relativity. These fields have an angular momentum density in the reference frame at rest with respect to the axis of symmetry; their Poynting vector form closed integral lines around the symmetry axis. In order to describe the state of motion of the electromagnetic field, two sets of observers are introduced: the inertial set, whose members are at rest with the symmetry axis; and the noninertial set, whose members are rotating around the symmetry axis. The rotating observers measure no Poynting vector, and they are considered as comoving with the electromagnetic field. Using explicit calculations in the covariant 3 + 1 splitting formalism, the velocity field of the rotating observers is determined and interpreted as that of the electromagnetic field. The considerations of the rotating observers split in two cases, for pure fields and impure fields, respectively. Moreover, in each case, each family of rotating observers splits in two subcases, due to regions where the electromagnetic field rotates with the speed of light. These regions are generalizations of the light cylinders found around magnetized neutron stars. In both cases, we give the explicit expressions for the corresponding velocity fields. Several examples of relevance in astrophysics and cosmology are presented, such as the rotating point magnetic dipoles and a superposition of a Coulomb electric field with the field of a point magnetic dipole.

Calcul et mesure des forces et couples appliqués à un cristal uniaxe traversé par l'onde extraordinaire

1974 ◽  
Vol 52 (19) ◽  
pp. 1903-1913 ◽  
Author(s):  
Gérald Roosen ◽  
Christian Imbert
Keyword(s):  
Poynting Vector ◽  
Extraordinary Wave ◽  
Momentum Density ◽  
Experimental Results ◽  
Variable Pressure ◽  
Anisotropic Crystal ◽  
Torque Measurements ◽  
Maxwell Tensor

We derive from the Maxwell tensor the forces and torques applied to a uniaxial anisotropic crystal when an extraordinary wave passes through it, and we show that the momentum to be associated with the wave in the crystal is collinear with the Poynting vector. Next, we present experimental results of torque measurements using, successively, two uniaxial anisotropic crystals placed inside a variable pressure container. We finally compare our results with those obtained by other authors and show that, according to the types of experiments, either Abraham's or Minkowski's momentum density will appear. [Translated by the journal]

The Poynting vector and angular momentum density of the autofocusing Butterfly-Gauss beams

2018 ◽  
Vol 105 ◽  
pp. 23-34 ◽  
Author(s):  
Ke Cheng ◽  
Gang Lu ◽  
Yan Zhou ◽  
Na Yao ◽  
Xianqiong Zhong
Keyword(s):  
Angular Momentum ◽  
Poynting Vector ◽  
Momentum Density

scholarly journals Radiation forces and the Abraham–Minkowski problem

2018 ◽  
Vol 33 (10n11) ◽  
pp. 1830006 ◽  
Author(s):  
Iver Brevik
Keyword(s):  
Casimir Effect ◽  
Momentum Density ◽  
Minkowski Problem ◽  
Mechanical Subsystem ◽  
Radiation Forces ◽  
Electromagnetic Momentum ◽  
Conservation Principles ◽  
Experimental Findings ◽  
Inherent Ambiguity ◽  
Correct Expression

Recent years have witnessed a number of beautiful experiments in radiation optics. Our purpose with this paper is to highlight some developments of radiation pressure physics in general, and thereafter to focus on the importance of the mentioned experiments in regard to the classic Abraham–Minkowski problem. That means, what is the “correct” expression for electromagnetic momentum density in continuous matter. In our opinion, one often sees that authors over-interpret the importance of their experimental findings with respect to the momentum problem. Most of these experiments are actually unable to discriminate between these energy–momentum tensors at all, since they can be easily described in terms of force expressions that are common for Abraham and Minkowski. Moreover, we emphasize the inherent ambiguity in applying the formal conservation principles to the radiation field in a dielectric, the reason being that the electromagnetic field in matter is only a subsystem which has to be supplemented by the mechanical subsystem to be closed. Finally, we make some suggestions regarding the connection between macroscopic electrodynamics and the Casimir effect, suggesting that there is a limit for the magnitudes of the cutoff parameters in QFT related to surface tension in ordinary hydromechanics.

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