共查询到19条相似文献,搜索用时 140 毫秒
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讨论了垂直入射的、频率为ωg的平面高频引力波对环形波导管中频率为ωe的电磁波的调制作用.一般情况下,在波导管中与引力波传播方向垂直的对称平面附近,电磁波的能流密度会出现三种新的频率成分(2ωe±ωg)和ωg.在ωg》ωe时,能流密度振幅的相对调制量与引力波的无量纲振幅h0数量级相同.特别是当ωg,ωe和电磁波绕波导传播的绕行频率ω0满足关系ωg=2ωe》ω0时,由于类似于共振的机制,能流密度会出现比h0大几个数量级的振幅相对调制量.这个结果不会由于参数的微小改变而消失,这对于探测极微弱的引力辐射信号将是十分重要的
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根据经典力学、电磁学知识和经典色散理论导出了介质对高频电磁波的色散规律,由此色散规律可以清楚看出几乎所有介质对于高频电磁波来说都成为透明介质,并以金属铜为例进行了验证.据此人们可以容易地理解高频电磁波的某些应用. 相似文献
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通过电磁场的相对论变换,指出运动媒 质中电磁波场 E与D之间、B与H之间,v(射 线速度)与ω(法线速度)之间将发生方向的分 化,并给出了v、ω与s(能流密度)的相应表 述式. 相似文献
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电磁波在多层介质内的透射 总被引:5,自引:0,他引:5
导了多层介质中透射电磁波的电场振幅与介质表面入射电磁波场电场振幅之间的关系式,引入了一个母函数,通过微分可以生成介质各层中的透射波。 相似文献
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Ashok K. Singal 《General Relativity and Gravitation》1997,29(11):1371-1390
The electromagnetic field of a charge supported in a uniform gravitational field is examined from the viewpoint of an observer falling freely in the gravitational field. It is argued that such a charge, which from the principle of equivalence is moving with a uniform acceleration with respect to the (inertial) observer, could not be undergoing radiation losses at a rate implied by Larmor's formula. It is explicitly shown that the total energy in electromagnetic fields, including both velocity and acceleration fields, of a uniformly accelerated charge, at any given instant of the inertial observer's time, is just equal to the self-energy of a non-accelerated charge moving with a velocity equal to the instantaneous present velocity of the accelerated charge. At any given instant of time, and as seen with respect to the present position of the uniformly accelerated charge, although during the acceleration phase there is a radially outward component of the Poynting vector, there is throughout a radially inward Poynting flux component during the deceleration phase, and a null Poynting vector at the instant of the turn around. From Poynting's theorem, defined for any region of space strictly in terms of fixed instants of time, it is shown that a uniformly accelerated charge does not emit electromagnetic radiation, in contrast to what is generally believed. Contrary to some earlier suggestions in the literature, there is no continuous passing of electromagnetic radiation from a uniformly accelerated charge into the region inaccessible to a co-accelerating observer. 相似文献
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Propagation of electromagnetic waves in a medium with zigzag carbon nanotubes is studied. Based on the Maxwell equations, an effective equation for the electromagnetic field vector potential is derived, which takes into account ion oscillations in the dielectric medium with nanotubes. It is found that the pulse shape depends on the character of oscillations of heavy ions, which may absorb the electromagnetic field, and on other parameters of the problem. 相似文献
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M. Amooshahi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(1):115-118
A canonical relativistic formulation is introduced to quantize
electromagnetic field in the presence of a polarizable and
magnetizable moving medium. The medium is modeled by a continuum of
the second rank antisymmetric tensors in a phenomenological way. The
covariant wave equation for the vector potential and the covariant
constitutive equation of the medium are obtained as the Euler-Lagrange equations using the Lagrangian of the total system.
A
fourth rank tensor which couples the electromagnetic field and the
medium is introduced. The susceptibility tensor of the medium is
obtained in terms of this coupling tensor. The noise polarization
tensor is calculated in terms of both the coupling tensor and the
ladder operators of the tensors modeling the medium. 相似文献
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Technical Physics - Vertical components of the vector potential of electromagnetic wave above two-layer strongly inductive impedance medium are determined. The solution is represented as a... 相似文献
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We study the energy characteristics of fields radiated from electric, magnetic, and toroidal dipoles in a nondispersive medium moving with velocity lower than the speed of light in this medium. The angular dependences of Abraham's energy-flux density of electromagnetic field are analyzed. In particular, it is shown that if the medium velocity is high enough, then the radial component of the vector of energy-flux density is negative in a certain angular range. Expressions for the electromagnetic energy flux through a sphere of large radius are obtained. It is shown that if the velocity of a moving medium is high enough, then the energy flux is negative and its absolute value can exceed the energy losses of sources. 相似文献
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Daniel C. Cole 《Foundations of Physics》1999,29(11):1673-1693
Cross-term conservation relationships for electromagnetic energy, linear momentum, and angular momentum are derived and discussed here. When two or more sources of electromagnetic fields are present, these relationships connect the cross terms that appear in the traditional expressions for the electromagnetic (1) energy, (2) linear momentum, and (3) angular momentum, over to, respectively, (1) the sum of the rates of work, (2) the sum of the forces, and (3) the sum of the torques, that are due to the fields of each charge or current source acting upon the other charge and current sources. These relationships, although not new, appear to be rarely recognized and used in the physics literature. As shown here, they can be extremely helpful for solving and gaining a deeper physical understanding into a rather diverse range of interesting problems in electrodynamics, including (1) aspects of Poynting's theorem when applied to charged point particles, (2) the detailed physical basis of electrostatic analysis, (3) understanding the connection between different techniques used in the past for solving Casimir force problems, and (4) reconciling the invalidity of Newton's third law in electrodynamics. 相似文献
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V. O. Gladyshev 《Technical Physics》1999,44(5):566-569
An exact analytical solution is obtained for the trajectory of the wave vector of a monochromatic electromagnetic plane wave
in a medium with nonsimple motion. It is shown that the spatial dragging of the electromagnetic wave by the moving medium
can be described correctly in the general case only if relativistic terms of order β
2 are taken into account.
Zh. Tekh. Fiz. 69, 97–100 (May 1999) 相似文献
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Maxwell’s equations for an electromagnetic field propagating in an array of carbon nanotubes have been considered in the case when the velocity of the incident pulse is greater than the speed of light in the medium. The equation for the vector potential of the electromagnetic field has been derived and solved numerically. The dependence of the pulse on its velocity at the entrance to the array of carbon nanotubes has been revealed. 相似文献
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The scale-transformation of electromagnetic theory is investigated in detail based on the form of Maxwell equations in scale-transformation being unchanged in different coordinate systems. The relations of electromagnetic parameters in a rectangular coordinate system and in a spherical coordinate system are presented respectively. The scale-transformation invariants for electromagnetic field are derived and their physical meaning is also presented. It is indicated by simulation that the electromagnetic waves located in medium can be considered to be isotropic due to the fact that the size of propagating vector affected by the scale factors and observing azimuth is on a size of 10^-9, which provides a new approach for investigating the electromagnetic characteristics of ellipsoidal targets. 相似文献