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1.
Summary A recent electrokinematics theorem leads to a general equation that, through an arbitrary irrotational fieldF, connects the motion of the electric-charge carriers, the internal potential and the dielectric properties of a physical system with its external currents, voltages and powers. It has been proved for quasi-electrostatic fields,i.e. when the vector potential may be disregarded, and on the basis of classical mechanics. Here the theorem is extended to any type of electromagnetic field and to quasi-relativistic quantum mechanics, in the case of many-particle systems for which, moreover, the probability current density is suitably computed. The new equation so obtained, throughF, connects the external currents again with the internal electric permittivity and the scalar potential, in the same way as in the preceding approach, and with the carrier velocity that, however, has to be computed according to quantum mechanics. Moreover, it contains two new contributions, one deriving from the vector potential and the other from a current density arising from the electron spin. By means of proper choices ofF, new expressions of the external currents of the system are determined as functions of the motion of its internal carriers. In particular, the electrokinematics theorem is exploited to compute the output current in two-terminal nanoelectronic devices in which, owing to the small sizes, quantum effects cannot be disregarded. Finally, such results, when they are applied to the double-barrier tunnelling structures, allow us to show the splitting of the electron pulse into two uncorrelated pulses, and as a consequence, to obtain a possible shot noise suppression, up to fifty per cent of the full shot noise.  相似文献   

2.
Summary In this paper we clarify the sources of radiation in a number of experiments, concerning the electromagnetic impulse pendulum, carried out by various authors. The calculated radiated energy was found to be negligible, in all cases, compared to the energy stored in their systems, in contradiction to their claim. We elucidate the way by which Newton's third law is applicable and how the reaction force of the moving pendulum is transferred to the stationary frame. In the MIT experiment of Graneauet al., average values for quantities like the time constant, resistance etc. are given ignoring their standard deviations. Calculating and taking into account their errors, due to their dependence on the temperature, we found agreement between the theoretical and experimental values of the pendulum momentum.  相似文献   

3.
Summary Largely quantitative experiments by Pappas have indicated that the momentum imparted to an electrodynamic impulse pendulum was not balanced by an equal and opposite momentum change of field energy as required by the special theory of relativity. The authors repeated Pappas' experiment using discharge currents from a capacitor bank which contained a known amount of stored energy. It turned out that, for momentum conservation, the magnetic-field energy required would have been 1000 to 2000 times as large as the energy that was actually stored in the capacitors. In the second part of the paper the pendulum experiments are interpreted in terms of Ampère's force law. It is shown that the Ampère force exerted on the pendulum is almost exactly the same as the lorentz force, but it arises in different parts of the pendulum conductor. Furthermore, the Ampère reaction force does not reside in the field but in the stationary part of the circuit which supplies current to the pendulum. Hence in the Ampère electrodynamics the momentum is definitely conserved. The experimental and analytical findings confirm the work by Pappas. A new and important experimental fact emerged from the present investigation. The momentum imparted to the pendulum was found to be significantly smaller than the calculated mechanical impulse given by the Lorentz and Ampère force laws. The Ampère force distribution offers an explanation of this observation in terms of the elastic distortion of the pendulum structure. The Lorentz force distribution could not produce this distortion.
Riassunto Esperimenti ampiamente quantitativi di Pappas hanno indicato che l'impulso assegnato ad un pendolo ad impulso elettrodinamico non è bilanciato da un cambio d'impulso uguale e opposto dell'energia del campo come richiesto dalla teoria speciale della relatività. Gli autori ahnno ripetuto l'esperimento di Pappas usando correnti di scarico da una riserva di capacitori che contiene una quantità nota di energia immagazzinata. Risulta che, per la conservazione del momento, l'energia del campo magnetico richiesta sarebbe da 1000 a 2000 volte grande come l'energia che è in realtà immagazzinata nei capacitori. Nella seconda parte del lavoro gli esperimenti cel pendolo sono interpretati sulle basi delle leggi di forza di Ampère. Si mostra che la forza di Ampère esercitata sul pendolo è quasi esattamente uguale alla forza di Lorentz, ma essa si verifica in parti differenti del conduttore del pendolo. Inoltre, la forza di reazione di Ampère non sta nel campo, ma nella parte stazionaria del circuito che fornisce corrente al pendolo. Quindi nell'elettrodinamica di Ampère l'impulso è conservato in maniera definita. I risultati sperimentali e dell'analisi confermano il lavoro di Pappas. Da questo studio è emerso un nuovo ed importante fatto sperimentale. Il momento impartito al pendolo appare essere specificativamente piú piccolo dell'impulso meccanico calcolato fornito dalla leggi di forza di Lorentz ed Ampère. La distribuzione di forze di Ampère offre una spiegazione di questa osservazione in termini di distorsione elastica della struttura del pendolo. La distribuzione di forze di Lorentz potrebbe non produrre questa distorsione.

Резюме Количественные эксперименты Паппаса показывают, что импульс, переданный электромагнитному импульсному маятнику, не компенсируется равным и противоположным изменением импульса поля, как это следует из специальной теории относительности. Авторы повторили эксперимент Паппаса, используя разряд батареи конденсаторов, которая содержит известное количество запасенной энергии. Оказывается, что для охранения импульса требуемая энергия магнитного поля должна в 1000–2000 раз превосходить энергию, фактическн запасенную в конденсаторах. Во второй части статьи эксперименты с маятником интерпретируются в терминах закона для силы Ампера. Показывается, что сипа Ампера, действующая на мятник, оказывается точно такои же, как сила Лоренца, но возникает в разных частях прводника маятника. Кроме того, сила реакции Ампера принадлежит не полю, а стационарной части контура, который подводит ток к маятнику. Следовательно, электродинамический импульс Ампера сохраняется. Экспериментальные и теоретические результаты подтверкдают работу Паппаса. Из проведенных исследований получен новый и важный зкспериментальный результат. Обнаружено, что импульс, переданный маятинку, оказывается знапительно меньше, чем вычесленный механический импульс, определяемый законами для сил Ампера и Лоренца. Распеделение силы Ампера предлагает объяснение этого факта с помощью упругой деформации структуры маятника. Распределение силы Лоренца не может создавать такой деформации.
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A recent proposal to explore vacuum electrodynamics using the speed of propagation of an electromagnetic wave through an ambient constant magnetic field is examined. It is argued that the proposal should be modified so that the background magnetic field, the direction of propagation and the transverse projection of the electric field (with respect to the direction of propagation) are not coplanar. The implications of invariance under Gibbons' electric-magnetic duality rotations are determined in this context.https://doi.org/10.1209/0295-5075/100/60005  相似文献   

6.
    
The Galilean constitutive equations for the electrodynamics of moving media are derived for the first time. They explain all the historic and modern experiments which were interpreted so far in a relativistic framework assuming the constant light celerity principle. Here, we show the latter to be sufficient but not necessary.https://doi.org/10.1209/0295-5075/84/20002  相似文献   

7.
    
The definition of the induced emf as the integral over a closed loop of the Lorentz force acting on a unit positive charge leads immediately to a general law for electromagnetic induction phenomena. The general law is applied to three significant cases: moving bar, Faraday's and Corbino's disc. This last application illustrates the contribution of the drift velocity of the charges to the induced emf : the magneto-resistance effect is obtained without using microscopic models of electrical conduction. Maxwell wrote down “general equations of electromotive intensity” that, integrated over a closed loop, yield the general law for electromagnetic induction, if the velocity appearing in them is correctly interpreted. The flux of the magnetic field through an arbitrary surface that have the circuit as contour is not the cause of the induced emf. The flux rule must be considered as a calculation shortcut for predicting the value of the induced emf when the circuit is filiform. Finally, the general law of electromagnetic induction yields the induced emf in both reference frames of a system composed by a magnet and a circuit in relative uniform motion, as required by special relativity.https://doi.org/10.1209/0295-5075/81/60002  相似文献   

8.
    
The concept of Maxwell's displacement current is still not fully understood. In this paper,we measured the magnetic field between the plates of a charging capacitor using a magneto-optical method,which is generally explained to be produced by Maxwell's displacement current. We observed the asymmetric radial profile of the magnetic field between them,which could not be explained by using the displacement current. In contrast,it could be explained naturally,if we assumed that the magnetic field was produced by the practically existing conduction currents,which consist of the surface currents on the plates,the current in the charging wires connected to it and the return current connected to the electric power supply.https://doi.org/10.1209/0295-5075/131/30004  相似文献   

9.
    
We consider a metric consisting of a gravitational background part and an electromagnetic part. We show that the Lorentz force equations follow exactly from the geodesic equation for this metric and that in the Dirac gauge the Einstein-Hilbert action reduces to gravitation with electromagnetism as long as the background part is much stronger than the electromagnetic one.https://doi.org/10.1209/0295-5075/130/50005  相似文献   

10.
    
A new type of magneto-optical effect in piezoelectrics is predicted. A low-frequency behavior of the Faraday effect is found.https://doi.org/10.1209/0295-5075/90/17001  相似文献   

11.
    
Typical problem of photonics and plasmonics is the scattering of a plane wave by objects with different shapes. Particularly,in quantum mechanics,the general method to get an approximate solution of the scattering problem is the Born series. However,it is not directly applicable to electromagnetic problems because the boundary conditions are different. In this paper,we develop an advanced,optics-compliant,Born approximation,which obeys these conditions. A formula for the field scattered on two dielectric cylinders is derived. We test its accuracy by comparison with the numerical calculations.https://doi.org/10.1209/0295-5075/127/20002  相似文献   

12.
We prove that the nonaffine conformal transformations of four-dimensional Minkowski space are necessarily global causality violators, and use this fact to obtain an elementary group-theoretic proof of the theorem that global causality implies the Lorentz group.  相似文献   

13.
    
We analyse the Anderson-Higgs mechanism of photon mass acquisition in a plasma and study the contribution to the mass from the orbital angular momentum acquired by a beam of photons when it crosses a spatially structured charge distribution. To this end we apply Proca-Maxwell equations in a static plasma with a particular spatial distribution of free charges, notably a plasma vortex, that is able to impose orbital angular momentum (OAM) onto light. In addition to the mass acquisition of the conventional Anderson-Higgs mechanism, we find that the photon acquires an additional mass from the OAM and that this mass reduces the Proca photon mass.https://doi.org/10.1209/0295-5075/90/45001  相似文献   

14.
    
A Brillouin-Wigner perturbation theory is developed for open electromagnetic systems which are characterised by discrete resonant states with complex eigenenergies. Since these states are exponentially growing at large distances, a modified normalisation is introduced that allows a simple spectral representation of the Green's function. The perturbed modes are found by solving a linear eigenvalue problem in matrix form. The method is illustrated on exactly solvable one- and three-dimensional examples being, respectively, a dielectric slab and a microsphere.https://doi.org/10.1209/0295-5075/92/50010  相似文献   

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16.
    
We assume a constant current density in a homogeneous one-component plasma of infinite extent and calculate the resulting magnetic energy per particle. Our starting point is the conserved approximately relativistic (Darwin) energy for a system of electromagnetically interacting particles that arises from the neglect of radiation. For the idealized model of a homogeneous one-component plasma the energy only depends on the particle canonical momenta and the vector potential. The vector potential is then calculated in terms of the canonical momenta using recent theoretical advances and the plasma Hamiltonian is obtained. The result can be understood either as due to the energy lowering caused by the attraction of parallel currents or, alternatively, as due to the inductive inertia associated with the flow of net current.https://doi.org/10.1209/0295-5075/84/20011  相似文献   

17.
We address the problem of inertial property of matter through analysis of the motion of an extended charged particle. Our approach is based on the continuity equation for momentum (Newton’s second law) taking due account of the vector potential and its convective derivative. We obtain a development in terms of retarded potentials allowing an intuitive physical interpretation of its main terms. The inertial property of matter is then discussed in terms of a kind of induction law related to the extended charged particle’s own vector potential. Moreover, it is obtained a force term that represents a drag force acting on the charged particle when in motion relatively to its own vector potential field lines. The time rate of variation of the particle’s vector potential leads to the acceleration inertia reaction force, equivalent to the Schott term responsible for the source of the radiation field. We also show that the velocity dependent term of the particle’s vector potential is connected with the relativistic increase of mass with velocity and generates a longitudinal stress force that is the source of electric field lines deformation. In the framework of classical electrodynamics, we have shown that the electron mass has possibly a complete electromagnetic origin and the obtained covariant equation solves the “4/3 mass paradox” for a spherical charge distribution.  相似文献   

18.
    
Circular microresonators (microdisks) are micron size dielectric disks embedded in a material of lower refractive index. They possess modes with complex eigenvalues (resonances) which are solutions of analytically given transcendental equations. The behavior of such eigenvalues in the small opening limit, i.e. when the refractive index of the cavity goes to infinity, is analyzed. This analysis allows one to clearly distinguish between internal (Feshbach) and external (shape) resonant modes for both TM and TE polarizations. This is especially important for TE polarization for which internal and external resonances can be found in the same region of the complex wave number plane. It is also shown that for both polarizations, the internal as well as external resonances can be classified by well-defined azimuthal and radial modal indices. https://doi.org/10.1209/0295-5075/87/34003  相似文献   

19.
    
If the conventional Maxwell-Lorentz formulation of classical electrodynamics is adopted in a flat spacetime of arbitrary odd dimension, then the retarded vector potential Aμ generated by a point charge turns out to be pure gauge, Aμ=∂μχ. By Gauss' law, the charge shows up as zero. The classical electromagnetic coupling is thus missing from odd-dimensional worlds. If the action is augmented by the addition of the Chern-Simons term, then the classical interaction picture in the three-dimensional world becomes nontrivial.https://doi.org/10.1209/0295-5075/96/60001  相似文献   

20.
    
A symmetric and conserved energy-momentum tensor for a scalar field in a moving medium is derived using the Gordon metric. When applied to an electromagnetic field, the method gives a similar result. This approach thus points a way out of the old Abraham-Minkowski controversy about the correct energy-momentum tensors for the electromagnetic field in a material medium. The new tensor describes the properties of the field alone while the Abraham tensor contains information about the field coupled to the medium.https://doi.org/10.1209/0295-5075/99/50002  相似文献   

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