均匀磁场中转动的导体上电荷的分布

指出了在均匀磁场中运动的轴对称导体上分布的电荷所产生的附加磁场是很弱的，在忽略附加磁场时导体内的电荷是均匀分布的，并求出导体球上电荷分布。     

圆柱形导体在均匀磁场中运动时的电荷分布

以圆柱形导体为例,介绍导体在均匀磁场中匀速运动时电荷分布的求解方法。计算结果表明:在均匀磁场中作垂直切割磁力线匀速运动的圆柱形导体,其电荷既分布在两底面,也分布在侧面,而且侧面电荷较多。对于细长的圆柱形导线,其侧面的电荷面密度几乎与导线中点的距离成正比。     

导体环在交变磁场中受的力

导出了导体环在一般交变磁场中的平均受力公式,以交变磁偶极子场为例讨论了导体环的受力方向,探讨受力大小与频率ω、导体环自感L等因素的关系.     

导体棒在磁场中运动问题归类例析

电磁感应中的力学问题,常以导体棒在磁场中运动的形式出现.导体棒在导电滑轨上运动,切割磁感线,产生感应电动势,使闭合回路中产生感应电流,导体棒受到安培力作用而使运动状态发生变化.因此感应电流与导体棒的加速度是一种相互制约的动态变化关系,最终导体棒达到某种稳定状态.下面结合具体实例对这种问题归类解析.     

导体在变化磁场中的感生电动势和电压

基于变化磁场产生感生电场分布的特点,以圆形变化磁场区域中放置的圆环导体为例,计算了圆环导体中的感生电动势和导体任意二点间的电压。最后给出了解决此类问题的方法。     

导体对磁场的屏蔽作用分析

分析了导体球壳对静磁场和对交变磁场的屏蔽作用,讨论了影响导体球壳对静磁场和对交变磁场的屏蔽作用的因素.     

也谈均匀磁场中旋转的中性轴对称导体上的电荷分布

严格证明了中性轴对称导体在均匀外磁场中旋转时,等势面为同轴圆柱面,并由电荷守恒定律证明该轴上的磁场精确等于外磁场Bo。同时还得出了该导体表面电荷密度的普遍公式。     

轴对称导体在均匀磁场中转动时的电荷分布及其电磁场的求解方法

指出了某些文献中的问题,根据电荷守恒定律,证明了由转动磁场所导致的电场E=±v×B的散度,并非与真实的电荷体密度有本质上的关联,而只是一种相对论效应.并根据电磁场变换原理,给出了轴对称导体在均匀稳恒磁场中转动时表面电荷密度及其电磁场的求解方法,得出了在均匀稳恒磁场中转动的导体球表面电荷密度及其电磁场.     

对"均匀磁场中转动的导体上电荷的分布"一文的商榷

<大学物理>1999年第1期中的一篇文章"均匀磁场中转动的导体上电荷的分布"给出了在均匀磁场中转动的轴对称导体产生的磁场的精确解和略去附加磁场后导体球上的电荷分布. 求解电荷分布的方法是巧妙的,在求解磁场分布之前曾用反证法证明了导体内电场的等势面是与导体共轴的柱面这样一个命题,并依此命题为基础求出了导体内磁场的精确解,因此该命题是否成立关系到所求的磁场精确解是否正确的问题.证明时原文使用了"设为a (见图1),则在x轴的球内一段上会有一些点的电势相等"这样一个关键判断,本文认为此判断令读者费解.     

轴向变化磁场中导体电势问题的讨论

应用类比法计算了截面为矩形的轴向变化磁场激发感生电场,并且讨论了处于这类感生电场中导体的电势问题.     

On the dynamics of a particle on a cone

A detailed study of the classical and quantum mechanics of a free particle on a double cone and a particle bound to its tip by a harmonic oscillator potential is presented.     

On the dynamics of a particle on a hyperboloid

A free particle moving on a one-sheeted hyperboloid is discussed both at the classical and quantum levels.     

Energy losses of a charged particle in a plasma in the presence of a strong electric field as a function of the sign of the charge

Institute of Radiophysics and Electronics, Academy of Sciences of the Armenian SSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 4, pp. 347–351, April, 1991.     

On the asymmetry of a random walk in the presence of a field

Any ensemble of random walks with symmetric transition probabilities will have symmetric properties. However, any single realization of such a random walk may be asymmetric. In an earlier paper, Weiss and Weissman developed a measure of asymmetry and applied it to random walks in the absence of a field, showing that the degree of asymmetry (in the diffusion limit) is independent of time and that the most probable degree of asymmetry corresponds to the maximum possible. We show in the present paper how the presence of a symmetric field can change this result, both in making the degree of asymmetry depend on time, and driving the random walk toward a more symmetric state.     

Influence of the Porosity of the Surface of a Graphite Furnace on the Atomization of a Sample

The influence of the wear of a tube graphite furnace and the morphological features of its surface on the formation of an atomic-absorption signal has been investigated. Electron-microscopic and mass-spectrometric investigations have shown that, prior to atomization, copper in the form of elementary metal microparticles is found not only on the surface of the furnace but also in the bulk of its pores. Free atoms are formed as a result of the concurrent processes of atomization of a sample on the surface of the furnace and in the bulk of its pores. The change in the apparent energy of formation of free atoms of metals interacting actively with graphite in the process of atomization and the inflection on their Arrhenius plot have been explained qualitatively.     

Influence of the polarity of a medium on the photonics of a merocyanine dye with a high quadratic polarizability

The influence of the polarity of a medium on the spectral and luminescent properties of 2-[(2E,4E)-6-(1,3,3-trimethyl-2,3-dihydro-1H-2-indolyliden)-2,4-hexadienyliden]malononitrile (THDM) in solutions and polymer matrices is studied at room temperature under conditions of steady-state and pulsed laser excitation. A large bathochromic shift of the absorption spectra observed upon an increase in the polarity of a solvent is caused by a strong increase in the molecular dipole moment μ due to a transition of molecules from the ground state (μ_g = 7.6 D) to an excited Franck-Condon state (μ^FC = 33.5 D). Based on the solvatochromic data, the quadratic polarizability was calculated to be β = (3.2 ± 0.6) × 10^?28 esu, which is close to the experimentally determined value β_ex = (3.9 ± 0.2) × 10^?28 esu. A strong narrowing of the fluorescence spectra in comparison with the absorption spectra is observed upon an increase in the solvent polarity. This narrowing is explained by a decrease in the bond length alternation parameter and by weakening of vibronic interactions in the singlet excited state. The dynamic solvatofluorochromism of THDM in the picosecond range is caused by reorientations of molecules of the polar environment occurring during a time period consistent with the dielectric relaxation time of these molecules.     

Anisotropy of the oscillation dynamics of a breather on a trap in the electroconvective twist structure of a nematic

The oscillation dynamics of dislocations with a dissociated nucleus in the electroconvective twist structure of a nematic liquid crystal has been studied. The initial state of the roll twist structure is unstable. One of the origins of this is the helical flows of the nematic in the neighboring rolls with the antiparallel axial velocity components. As a result, oscillating or “breathing” defects are formed, which have the properties of breathers and are described by the sine-Gordon equation. It has been demonstrated that the space-time anisotropy of the character of motion of the dislocations in opposite directions orthogonal to the roll structure takes place in such a nonstationary system.