趋肤效应演示仪器的设计

介绍了一个演示趋肤效应的实验装置,该装置结构简单,现象明显,演示内容全面,可加深对趋肤效应的理解,达到观察、研究趋肤效应的目的。     

趋肤效应演示仪

本文介绍以镀铁细铜丝与同样粗细的铜丝对比的方法，使用低频信号演示趋肤效应的基本思想，以及根据这一思想而设计出的趋肤效应演示仪。     

趋肤效应的演示

趋肤效应的演示赵立娟（吉林大学物理系长春１３００２３）趋肤效应是一种重要的电磁感应现象，除了在课堂讲授外，最好进行直接的演示才能使学生信服．传统的作法是用米波发生器做高频幅射电源，在两个等长的铜棒中间焊接两个完全相同的小灯泡（一个焊接在外表皮上，另一...     

角动量演示仪器的设计

设计了角动量演示装置 ,该装置结构简单 ,便于携带 ,可较好的演示角动量守恒和决定转动惯量的因素等 .     

摩擦力演示装置

在学习摩擦力时，很多同学感到有一定的困难．笔者利用带滚轮的演示小车和轻质弹簧配合，经过组合改装，制成摩擦力演示装置．该装置取材容易，制作简单、演示直观、操作方便、现象明显，适用于演示静摩擦力和滑动摩擦力．现将该装置的制作和使用方法介绍如下．     

趋肤效应演示器

趋肤效应是一种重要的电磁感应现象。在电磁学教学中,除了对这种现象作定性的解释之外,还必须用实验直接演示才能使学生信服。为了演示这种现象,我们用米波发生器做高频辐射源,它通过天线向空间发射电磁波。用一根长1.2米截成两半的铜棒做     

基于微控单元的胡克定律实验改进装置

利用自制的基于89C51微控单片机的胡克定律演示实验装置对传统的胡克定律演示实验进行了改进,改进后的实验装置用超声波精确测量弹簧的长度,在显示屏上能够直观地显示出实验温度和弹簧的长度,进而确定形变量及弹簧的弹性系数。与传统演示实验装置相比,该装置具有操作简单、直观性强、实验测量结果精确等优点,不仅可以作为教具用于课堂演示,而且可为弹簧系数的测量提供一种新的方法。     

洛伦兹力演示仪

对新课标中"洛伦兹力演示仪器"进行了改进,改进后的装置能够探究洛伦兹力F与磁场B、带电粒子q以及带电粒子运动速度v之间的关系,借助激光器能让学生更好地看到带电粒子所受洛伦兹力的情况、演示装置结构简单,操作方便,演示效果好,能提高洛伦兹力的课堂教学质量,激发学生学习兴趣.     

绝热去磁演示实验装置

本文简要介绍了绝热去磁降温的基本原理，并详细阐述了这一演示实验装置的设计思想和实验操作步骤．该实验装置结构简单，操作方便，便于在课堂演示绝热去磁效应．除此之外，它还可演示材料的顺磁和抗磁特性．     

几个静电演示实验

这里介绍的一组演示实验,主要是以中学物理教学大纲为依据的。它们在演示方法上、材料选择上以及实验原理上都较新颖,而且具有取材容易、构造简单、制作方便、表现力和感染力强等特点。一、电荷的相互作用 [演示器材] 橡皮泥(商店有售)、铅笔、试管、塑料筷子一双、有机玻璃筷子一只、丝绸一块。 [装置及演示方法]装置如图1所     

一个用简单物理模型构建的加密系统

一些简单的物理模型可产生复杂的行为,并有很强的逻辑表达能力.基于旋转元器件和格子气两个物理模型设计了一个加密系统,具有可逆、并行、简单、高效的特性.实验结果证实该系统具有良好的随机性和敏感性.研究结果表明,采用简单物理模型构建加密系统是一种很有潜力的方法. 关键词： 物理模型 加密系统 并行 效率     

非晶合金及合金液体的局域五次对称性

简要回顾了从20世纪30年代至今,有关非晶合金及合金液体的局域结构五次对称性的实验、理论和模拟研究.在简单液体的早期研究中,人们已经意识到五次对称性在简单液体的无序结构、过冷和晶化等起着重要作用,二十面体短程序作为五次对称性的典型代表受到了广泛关注.自从Frank提出简单液体中二十面体短程序的结构单元,大量的理论和实验研究已经明确在简单液体、合金液体和金属玻璃中存在局域五次对称性,并且建立了局域五次对称性与合金液体复杂动力学行为、玻璃转变、液体-液体相变以及非晶合金的形变等统一的定量描述和物理图像,表明了局域五次对称性作为结构参量的简单、普遍和有效性.     

The ground state of a strongly correlated fermion system in a magnetic field

A new variational method is used to investigate the ground state of the Hubbard model with a half-filled band for a one-dimensional chain, a planar square lattice, and a simple cubic lattice. A metamagnetic transition is found to occur in a one-dimensional chain and a simple square lattice. A simple cubic lattice does not undergo the metamagnetic transition.     

一类高维耦合的非线性演化方程的简单求解

利用一个简单的变换，一类高维耦合的非线性演化方程可以被约化为一低维的简单方程，将已有的求解法应用于简单方程，十分简捷的获得了原方程大量的精确解. 关键词： 非线性耦合方程 精确解 tanh函数方法     

Optical surface modes of lattice vibrations

Two simple methods, based on simple crystal models, for estimating the longitudinal optical surface vibration mode frequencies which lie in a LALO gap are examined. One method consists of deriving and solving a single-variable equation for the surface mode frequency, which depends only on the experimental bulk dispersion curves. The other method consists of fitting the known dispersion curves of a simple one-dimensional model, for which the optical surface mode frequency is given by a simple expression, to experimental bulk dispersion curves of more complex crystals. The results are compared with detailed theoretical surface mode calculations. The latter method is found to give better estimates.     

The soliton-like solutions to the （2＋1）-dimensional modified dispersive water-wave system

By a simple transformation, we reduce the (2 1)-dimensional modified dispersive water-wave system to a simple nonlinear partial differential equation. In order to solve this equation by generalized tanh-function method, we only need to solve a simple system of first-order ordinary differential equations, and by doing so we can obtain many new soliton-like solutions which include the solutions obtained by using the conventional tanh-function method.     

A high-stability medium based on CaF<Subscript>2</Subscript>:Na crystals with colloidal color centers: I. Photothermochemical conversion of colloidal color centers in CaF<Subscript>2</Subscript>:Na crystals

Photothermochemical conversion of simple color centers (which include from one to four anionic vacancies) and highly aggregated ones in additively colored crystals of calcium fluoride doped by sodium is studied. The annealing of crystals with a low sodium content in a reducing atmosphere (additive coloration) leads to the predominant formation of simple color centers, which convert into highly aggregated centers under the joint action of heating and irradiation in absorption bands of simple centers. The irradiation of highly aggregated centers into their absorption bands and simultaneous heating causes these centers to convert into simple centers. The additive coloration of crystals with a relatively high sodium content leads to the predominant formation of highly aggregated centers. The heating of these crystals along with the irradiation in absorption bands of highly aggregated centers causes these centers to convert into simple centers. The formation of different color centers in the course of additive coloration of crystals with different impurity content and different results of photothermochemical conversion of centers in these crystals are connected with the dual action of impurities. Anion vacancies, which compensate the charge of the impurity alkali metal, facilitate the aggregation of color centers. At the same time, the alkali impurity stabilizes simple color centers.     

On the Variety Generated by Bounded Pseudo-BCK-Algebras

In the paper we prove that the equational class V(bp\mathbb BCK)\mathcal{V}(bp\mathbb {BCK}) generated by the class bp\mathbbBCKbp\mathbb{BCK} of all bounded pseudo-BCK-algebras is generated by its simple members. As a matter of fact, we prove that simple members of V(bp\mathbbBCK)\mathcal {V}(bp\mathbb{BCK}) just coincide with relative simple bounded pBCK-algebras. Moreover, as a byproduct we show that every simple bounded pBCK-algebra can be embedded into a simple integral residuated lattice.     

Hall-Effekt und spezifischer elektrischer Widerstand flüssiger Übergangsmetalle

The Hall-coefficient and the electrical resistivity of liquid transition metals and their alloys with mono- and polyvalent simple metals have been measured with a sensitiveac current-ac magnetic field method. The transport properties of liquid transition metals are quite different from the well known behavior of liquid simple metals. The pure liquid metals La, Ce, Pr, Nd and U and also a great number of alloys of transition metals with simple metals show a positive sign of the Hall-coefficient. For alloys of transition metals with polyvalent simple metals we observed negative temperature coefficients of the electrical resistivity over large concentration ranges. This behavior can be understood by a modified form of the Faber-Ziman formula for the electrical resistivity of liquid metals.     

Stabilization of interchange modes by rotating magnetic fields

Interchange modes have been a key limiting instability for many magnetic confinement fusion configurations. In previous studies intended to deal with these ubiquitous instabilities, complex, transport enhancing, minimum-B producing coils were added to the otherwise simple linear mirror plasma. Possible solutions for returning to a simple symmetric mirror configuration, such as ponderomotive fields, are weak and difficult to apply. A new method is demonstrated here for the first time, utilizing rotating magnetic fields that are simple to apply and highly effective. A simple and easily comprehensible theory has also been developed to explain the remarkable stabilizing properties. Although this work has been performed on field reversed configurations, it should have a wide application to other confinement schemes, and could become a cornerstone for high-beta plasma stability.