共查询到19条相似文献,搜索用时 78 毫秒
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几种孤立带电导体的电荷面密度与曲率的关系 总被引:6,自引:1,他引:5
引言 本文试图计算某些形状规则的带电导体共电荷面密度与曲率的关系.本文的基本思路是:根据带电导体电场的电势[1],[2],可以求出导体表面的电荷密度(σ=E/4π=|φ|/4π).再利用微分几何有关曲率的知识,就可得到电荷密度与曲率的关系式. 下面先介绍微分几何有关曲率的知识.二、主曲率和总曲率[3] 平面曲线的曲率概念我们是熟悉的.下面我们说明曲面的曲率可以通过平面曲线的曲率来表示. 通过曲面上任一点M的法线,可以作出无穷多个平面,每个平面与曲面的交线称为M点的法截线.M点的法截线有无穷多条,每条都是平面曲线,都有确定的曲率.设M点… 相似文献
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普通物理学教材以尖端导体放电现象为例说明,曲率越大的地方,面电荷密度也越大,本文用两个不同的物理模型给尖端放电现象以理论解释. 相似文献
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本文就孤立导体面电荷密度与表面的曲率的关系进行定性地分析.带电导体处于静电平衡状态时,导体内部电场强度必定处处等于零,即E内=0.由E内=0,可以直接导出如下几点推论:(1)导体是等势体,表面是等势面;(2)导体表面场强处处与表面垂直;(3)由高斯定... 相似文献
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孤立导体带电时电荷在表面上如何分布是电磁学中一个很有意义的问题.中外的物理教科书都要讲到,表面曲率越大处,电荷密度也越大,但都未能给出一个正确的定量关系,这未免使人感到不足. 笔者对这个问题的研究结果指出,至少对几种表面形状(二次曲面)的导体来说,面电荷密度和表面曲率之间的确存在一个定量关系,这也许有助于我们对此问题的理解.一、表面弯曲程度的量度─—高斯曲率 按照微分几何,曲面在一点的弯曲程度由曲面在该点的高斯曲率表示.设曲面的方程为z=z(x,y),则曲面的高斯曲率为 现分别求出椭球面、双叶旋转双曲面、旋转椭圆抛物面的… 相似文献
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本文通过多重镜像法求解了等势条件下两个带电导体球的电荷分布问题,主要关注两球的电荷量以及平均面电荷密度随两球半径和两球间距的关系.通过选择合适的坐标,给出两导体球接触时,n级镜像电荷电量和位置的通式,及总电量的解析表达式.研究发现,当两导体球直接接触时,两球所带的电荷量可以严格求解,并给出了两球的电荷量之比表达式.随着两等势导体球间距的增大,两球所带的电荷量之比趋于半径之比.本文还讨论了一个导体球的半径趋于0的极限情况,小球与大球的电荷量之比趋于0,平均面电荷密度之比在两球不直接接触时趋于无穷大,而在两球直接接触时趋于π2/6. 相似文献
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对无限大导体表面,楔形导体表面,半圆柱形凸起表面电荷面密度进行了具体的计算,结果表明在静电平衡的条件下导体表面虽曲率相同,但表面电荷面密度却可以不同. 相似文献
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关于孤立带电导体表面上面电荷密度的分布问题,在普通物理学教科书中都有讨论,一般只是作为实验结论,在理论分析上比较粗略。本文试图从靜电场的基本性质出发,推导出电力线束发散程度与等位面的曲率之间的普遍关系式,从而定性地讨论孤立带电导体表面电荷分布情况。 相似文献
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利用有限差分法对有限长导体棒电荷面密度进行了数值模拟.数值模拟结果说明,有限长带电导体棒面电荷分布不仅与导体表面的曲率半径有关,还与导体的总体形状以及导体周围环境中其他导体的分布有关. 相似文献
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Self-consistent field theory of adsorption of flexible polyelectrolytes onto an oppositely charged sphere
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The adsorption of flexible polyelectrolyte (PE) with the smeared charge distribution onto an oppositely charged sphere immersed in a PE solution is studied numerically with the continuum self-consistent field theory. The power law scaling relationships between the boundary layer thickness and the surface charge density and the charge fraction of PE chains revealed in the study are in good agreement with the existing analytical result. The curvature effect on the degree of charge compensation of the total amount of charges on the adsorbed PE chains over the surface charges is examined, and a clear understanding of it based on the dependences of the degree of charge compensation on the surface charge density and the charge fraction of PE chains is established. 相似文献
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Thickness non-uniformities in electrostatic capacitors and in electroactive polymers – arising from manufacturing processes or electromechanical induced inhomogeneous deformations – may lead to drastic charge and electric field localizations and, ultimately, to an anticipated device failure. Based on a geometric interpretation of the Gauss equation enlightening the effect of the electrode curvature, we obtain an analytic expression of the electric field and of the surface charge density localization for non perfectly planar capacitors with symmetric thickness non-uniformities. The efficiency of the model is exploited by analyzing specific boundary value problems of technological interest. 相似文献
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In the framework of the density functional theory using a simple variational model we have calculated the first-order size corrections to electro-physical characteristics of small metal particles. We have discovered that the curvature correction to the surface energy is of positive sign. We have shown that it is possible to use macroscopic electrodynamics in calculations of the ionization potential and the electron affinity. We have determined the maximum charge which can be retained by a particle of a given size. 相似文献
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V. G. Pavlov 《Technical Physics》2004,49(12):1610-1616
It is shown that the conventional technique of substituting the field strength at the space charge-emitter interface that
is calculated with the Poisson equation into the Fowler-Nordheim formula considerably overestimates the effect of space charge
on field electron emission. In this work, the space-charge-induced field attenuation as a function of the emission current
density and radius of curvature of the emitter surface is derived using the model of a planar space-charge layer. It is argued
that field electron emission cannot be studied in terms of the spherical diode model, since it assumes the presence of a space
charge on the back (nonemitting) emitter surface, which is in fact absent. It is stated that one should consider the discrete
character of the charges when investigating the space charge in field electron emission, because the mean spacing between
the electrons emitted far exceeds the emission barrier width. 相似文献
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Size and curvature are important determinants of particle wettability, in addition to surface chemistry and texture. Hydration
free energy of a nonpolar solute scales with volume for small solutes and with surface area for larger ones. If the solute
acquires a surface charge, the scaling regimes can be affected, with size-dependence of the charge playing a critical role.
For isolated particles grown at fixed surface charge density, the Born approximation gives scaling of hydration free energy with volume.
We consider a distinctly different but practically important scenario, where the charged solute and surrounding counterions
are dissolved together. For this process, our molecular simulations demonstrate the electrostatic contribution to the solvation
free energy, calculated per unit area of the solute, to be virtually independent of solute size. We explain this behavior
in terms of counterion shielding effect on the curvature-dependent solute energy in the dehydrated state, an effect closely
balanced by the influence of dielectric screening in water. As a result, for moderate surface charge densities of the solute,
the net electrostatic contribution is dominated by counterion solvation, and scales with solute surface area independently
of the ionic strength in the solution. 相似文献
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R. F. Polishchuk 《Bulletin of the Lebedev Physics Institute》2017,44(11):313-317
The notion of the dimensionless gravitational charge defined through the Planck mass and the fundamental constants specifying this mass itself is introduced. The Big Bang is related to the unified physical interaction decay and the drop of Newton’s gravitational constant by 40.67 orders of magnitude in comparison with the electromagnetic constant taken as unity. This causes an increase in theMetagalaxy curvature radius by the same value and a decrease in the average density of space–time curvature sources by 122 orders of magnitude: from the maximum allowable Planck density to the observed critical density. The microphysics appears naturally related to cosmology. 相似文献