浅论正多边形带电环 盘 筒 柱的场强

根据文献[3]提供的公式,基于场强叠加原理,系统解析计算了正多边形带电环、盘、筒、柱中轴线上的电场分布,结果表明不同带电体的电场强度的代数性质与其电荷分布密切相关.从所做的几项计算中显示,环优于盘,筒优于柱.     

正多边形顶角和各边带电在中心处场强的计算

在正多边形每个顶角上各放置一个等量同种点电荷,则中心处合场强为零,对于这一结论本文给出了 3种证明方法;并进而分析了正多边形每个边均匀带电等情况     

带电正多边形盘轴线上的电场和磁场

利用直接积分方法,得到了均匀带电正多边形盘轴线上电场强度的解析表达式,以及均匀带电旋转正多边形盘轴线上磁场强度的解析表达式.     

探究均匀带电直线和圆弧产生电场的关系

利用微元法和对应性推证了均匀带电直线与均匀带电圆弧产生的电场等效; 利用微元法和对称性推 导了均匀带电圆弧在圆心的场强公式; 利用结论巧妙解答有关线性带电体的场强计算问题     

关于电场叠加问题的讨论

高斯定理本身没有非要孤立带电体不可的限制．将电场叠加原理应用于金属带电体系统时，必须注意到金属带电体在电场中的电荷重新分布．本文从理论上阐明用静电平衡时任一带电导体的分布电荷代入高斯定理计算的电场强度实际上已经是合电场，无须考虑其它带电体的电场的遗缺．     

叠加法求均匀带电球体电场问题

现有教材中计算均匀带电圆盘轴线电场强度公式,只得到场强大小,没有明确给出场点和圆盘的相对位置与场强方向之间的关系。若根据场强叠加的方法利用此公式计算均匀带电球体的场强分布,容易得到错误的结果。将符号函数引入均匀带电圆盘轴线上电场强度计算式,可以得到场强大小及相对于圆盘的方向,清楚而准确地给出均匀带电圆盘轴线电场强度。利用该公式再次求解均匀带电球体电场,结果与利用高斯定理得到的结果完全相符。     

关于均匀带电球面上电场强度的求解

由于均匀带电球面上的电场强度无法用高斯定理求出,现行大部分大学物理基础教材在讨论均匀带电球面产生的场强分布时,只用高斯定理求出了该带电系统内外空间电场的分布,并没有给出球面上场强的计算方法,只是指出在球面上场强值不连续.文章利用叠加原理和电容器能量的变化两种方法分别导出了均匀带电球面上任一点的场强值,验证了均匀带电球面的场强是不连续的,两种方法思路截然不同,但得到的结果完全相同,该结果使得高斯定理求出的均匀带电球面在空间电场分布的结论更加完整.     

旋转带电刚体的电偶极矩辐射功率及其阻尼力矩

依照电动力学有关电磁辐射的基本理论,在满足远场近似条件并在非相对论情形和准周期平均意义下,依据辐射过程的功能原理与能量守恒的法则,推导了旋转带电刚体的电偶极矩辐射的功率与阻尼力矩;所得公式在单个电偶极子情形的结论与已有文献的结论相符;枚举数例并列表计算了若干常见带电体的相关结果。     

数值积分求解均匀带电圆环平面上的电场分布

本文用数值积分的方法计算椭圆积分，求出在均匀带电圆环平面上的场强与电势．     

电各向异性介质中带电圆环的电势和场强

由电各向异性介质中连续带电体的电势公式,利用积分的方法,求得放置在电各向异性介质中的均匀带电圆环在其轴线上所激发的电势,并进而求得在其轴线上激发的场强。对求得的结果进行讨论,可得到在电各向异性介质中均匀带电圆环在其轴线上所激发的电势和场强的一些的特点。     

Compton scattering of 59.5 keV gamma rays from p-Si sample in an external electric field

This study is related to Compton scattering of photons from a p-Si sample whose surface charge density distributions are changed by an external electric field. The external electric field intensity in the range 0-75 kV/m was used to change the surface charge density distributions of the sample. The sample surface perpendicular to the electric field was selected as the scattering surface. The p-Si sample was bombarded by 59.5 keV γ-photons emitting from an Am-241 point source. The Compton scattered photons at an angle of 90^o were detected by an Si(Li) detector. The Compton scattering intensity suddenly increased with the application of the electric field since the applied electric field distorts both the negatively charged scattering center (free electron, bound electron, ionized acceptor) and the positively charged scattering center (hole) and their momentum distribution in the sample. There is a good third-order polynominal relation between the Compton scattering intensity and the increasing (or decreasing) electric field intensity. The results show that the positively charged scattering centers behave like negatively charged scattering centers, but the latter are slightly more effective than the former in the Compton scattering of γ-rays from the sample in the electric field.     

Incompressible Einstein–Maxwell fluids with specified electric fields

The Einstein–Maxwell equations describing static charged spheres with uniform density and variable electric field intensity are studied. The special case of constant electric field is also studied. The evolution of the model is governed by a hypergeometric differential equation which has a general solution in terms of special functions. Several classes of exact solutions are identified which may be considered as charged generalizations of the incompressible Schwarzschild interior model. An analysis of the physical features is undertaken for the uniform case. It is demonstrated that uniform density spheres with constant electric field intensity are not realizable with isotropic pressures. This highlights the necessity of studying the criteria for physical admissability of gravitating spheres in general relativity which are solutions to the Einstein–Maxwell equations.     

Generation and detection of electromagnetic field with charged material oscillation

We generated an electromagnetic field using the spatial oscillation of a charged material such as a polyimide film. The film was vibrated with acoustic waves at 1 Hz–1 kHz. For charged films, changes in electric field intensity with acoustic wave irradiation were detected using an antenna. The electric field intensity and phase were found to be related to the surface voltage and electrical polarity. The surface potential distribution matches the electric field distribution that was measured by scanning the local excitation. These results indicate that this phenomenon can be used to measure the electrical properties of charged materials.     

A Tolman-like Compact Model with Conformal Geometry

In this investigation, we study a model of a charged anisotropic compact star by assuming a relationship between the metric functions arising from a conformal symmetry. This mechanism leads to a first-order differential equation containing pressure anisotropy and the electric field. Particular forms of the electric field intensity, combined with the Tolman VII metric, are used to solve the Einstein–Maxwell field equations. New classes of exact solutions generated are expressed in terms of elementary functions. For specific parameter values based on the physical requirements, it is shown that the model satisfies the causality, stability and energy conditions. Numerical values generated for masses, radii, central densities, surface redshifts and compactness factors are consistent with compact objects such as PSR J1614-2230 and SMC X-1.     

关于圆盘状物体的几个物理量的计算

在大学物理教学中,关于圆盘状物体的物理量有很多,如电学中带电圆环、带电圆盘,其周围空间产生的电场强度和电势怎样计算？关于铜质圆盘状物体在磁场中转动时产生的电动势的计算问题等;力学中圆盘的转动惯量、椭圆盘的转动惯量,圆盘状物体转动时的摩擦力矩问题、驱动力做功问题等.本文将对这些物理量进行分析,并找出一些共同的规律和特点,将其归纳总结,计算所需要的物理量.     

Electromagnetic emission of a strongly charged oscillating droplet

Analytical expressions for electric field in the vicinity of an oscillating strongly charged droplet of nonviscous conducting liquid and intensity of electromagnetic radiation are derived in the linear approximation with respect to perturbation amplitude of the droplet surface. Order-of-magnitude estimations of the radiation intensity are presented. The intensity of electromagnetic radiation of a ball lightning that can be simulated using a charged droplet is not related to the surface oscillations.     

静电场中电场强度的数值意义

“近场强远场弱”是静电场的普遍特点,宏观带电体的静电场是点电荷电场叠加的结果.本文以静电场中两个实际的电场强度问题为例,用相对数值比较了电荷分布对电场强度的贡献,阐述电场强度“近场强远场弱”的数值意义.     

高斯定理在带电导体表面上的应用

本在静电平衡条件的基础上,应用高斯定理讨论带电导体表面的电场强度。     

Development of a technique for measuring static electricity distribution using focused ultrasound waves and an induced electric field

A novel method is proposed for non-contact measurement of static electricity distribution on a surface using focused ultrasound to excite movement of the charge. The focused ultrasound is generated by controlling individually the phases of 285 airborne ultrasound transducers, and it was demonstrated local excitation could be measured. An electric field is induced by local excitation of a charged object. The electric field intensity and phase are related to the surface potential and electrical polarity of the object, respectively. It is possible to measure static electricity distribution over an entire object surface by scanning the position of the focused ultrasound.     

On Charged Analogues of Matese and Whitman Interior Solutions in General Relativity

A set of three static fluid spheres once derived by Matese and Whitman (in Phys. Rev. D 22:1270, 1980) are charged by means of a particular electric intensity to obtain compact objects like white dwarfs, quark stars and neutron stars etc. The charged objects so obtain and their neutral counterparts are analysed on astrophysical grounds. This revealed that two of the charged spheres and one of the neutral seed solutions are well behaved. The corresponding red shift and adiabatic index together with other physical entities like pressure, density and velocity of sound through the star models are studied systematically.