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Electromagnetic Properties of Superconductors
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2022
In classical electromagnetism, the movement of magnetic flux is only considered to have meaning if the magnet producing it moves. However, in Type II superconductors the flux is quantised in vortices, and any change in field produces an observable displacement of the flux lines. The scale of this displacement has considerable physical significance. If this distance is much less than the size of the vortex core, then the vortices do not move far in their potential wells and remain pinned. This produces a linear and reversible response to the applied field. If the flux is displaced by a distance of several vortex spacings, on the other hand, then vortices unpin, and we can use the critical state model.
Nuclear and Particle Physics
Published in Walter Fox Smith, Experimental Physics, 2020
Just as there was a time, centuries ago, that electric and magnetic phenomena were considered distinct, electromagnetic and weak forces are typically listed separately. Electric and magnetic phenomena were unified under Maxwell’s theory of classical electromagnetism in the 19th century, and more recently under the quantum field theory called quantum electrodynamics (or “QED”). QED remains the archetype of a quantum field theory. After its development, a quantum field theory with a unified explanation for both electromagnetic and weak phenomena was developed, called “electroweak” theory. Considered from this perspective, the separate electromagnetic and weak forces have been combined under a single electroweak description.
All About Wave Equations
Published in Bahman Zohuri, Patrick J. McDaniel, Electrical Brain Stimulation for the Treatment of Neurological Disorders, 2019
Bahman Zohuri, Patrick J. McDaniel
In this section, certain claims for the existence of non-Hertzian waves were examined in light of classical electromagnetism and quantum mechanics. In the process, the existence of scalar fields and waves were predicted. These are fields with long range and great penetrating power. The associated potential waves are longitudinal waves in contrast to the familiar transverse electromagnetic waves. The scalar waves cannot be detected directly because they do not impart energy and momentum to matter. On the other hand, they impart phase shifts to matter and they may be detected through interference means. Because of their elusive nature they may also be called scalar vacuum waves. The underlying scalar field is already known to physicists in the context of quantum field theory and is known as the scalar gauge field. It is gratifying that in this period of research other researchers reported the observation of fields which behaved qualitatively similar, to the predicted scalar fields. The extension of the forceless field concept to the nucleonic field should yield higher order fields with even more interesting properties than the scalar fields. This matter is being under investigation.
MHD natural convective flow of a polar fluid with Newtonian heat transfer in vertical concentric annuli
Published in International Journal of Ambient Energy, 2020
Lipika Panigrahi, J. P. Panda, G. C. Dash
The magnetohydrodynamic (MHD), combination of classical electromagnetism with fluid dynamics, has drawn considerable attention because of its different applications in astronomy and geophysics, etc. It is applied to the investigation of solar plasma, the extraction of geothermal energy and in the field of semiconductors. The influence of unsteady free convection and mass transfer flow of a polar fluid in the presence of a uniform magnetic field has been reported by Ogulu (2005). The oscillatory magnetohydrodynamic natural convection flows between vertical coaxial cylinders have investigated by Oudina and Bessaih (2016). Many researchers (Kataria and Patel 2018; Swain, Parida, and Dash 2018a; Swain, Parida, and Dash 2018b; Swain, Parida, and Dash 2019) have considered external magnetic field to act upon conducting fluid flow.
Electromagnetism at finite temperature: a density operator approach
Published in Journal of Modern Optics, 2020
It is pointed out that the photon wave function has nonlocal characteristics (10); nevertheless, there are analogies between classical electromagnetism and quantum mechanics. Quantum-like calculation can be performed by using this formulation in free space (12–14), in inhomogeneous anisotropic media, and in media with the presence of magneto-electric coupling (15, 16). Berry phase effects associated with the optical Dirac Hamiltonian have also been studied (17–21). In some literatures, dispersion correction has also been taken into account. To do so, the group permittivity and permeability are used in some works (22–24), while the simultaneous equations of the field equation and the equation of electrons motions are considered in other literatures, where the dissipation in the materials can also be calculated by the perturbation method (25–29).
On the maximizing problem associated with Sobolev-type embeddings under inhomogeneous constraints
Published in Applicable Analysis, 2019
Michinori Ishiwata, Hidemitsu Wadade
The functional inequality and the attainability of its best constant play an important role in the analysis of the real-world phenomena. One of the examples of such an interplay is the analysis of the stability of matter. It is well known that the classical electromagnetism yields the quick collapse of the hydrogen atom. This is because the orbital electron loses the energy very fast by the radiation of the electromagnetic wave due to the existence of the acceleration for the circle motion around the nuclear. In the standard textbook in physics, it is written that this difficulty is overcome by quantum mechanics and the stability due to the uncertainty principle of Heisenberg which states that the variance of the kinetic energy and the potential energy cannot be small simultaneously. The mathematical aspect of this principle is often based on a certain functional inequality which is called the Hardy inequality.