减小实验误差的三"选择"

实验设计的一般思路是，首先根据原理及可行性确定实验方案，其次选择实验器材、电路，最后进行数据处理和误差分析．选择操作性强的实验方案，选择合适的实验器材、电路，选择合适的处理实验数据的方法，可以减小实验误差，提高实验的精度．     

电场测绘实验中器材选用原则的研讨

利用稳恒电流场模拟静电场完成《电场中等势线的描绘》是中学新加的一个好实验,目前,对本实验中器材如何选用,还未见到较为系统的理论资料,使得完成实验处于被动和盲目状态。实验的主要器材有:导电纸、测量电表、电源、电极等,而这些器材本身各有不同规格,应该怎样选择是本文讨论的中心。测绘实验要求测绘误差不大于0.1×10~(-3)m,本实验就要求能把沿电力(流)线方向上相距0.1×10~(-3)m间电势差反映在电表上,以满足要求。为此我们选取导电纸上电势梯度最小的中部两个相距为△d=0.1×10~(-3)m的等势线a、b(a,b接近平行)间的导电纸为研究对象(如图1所示)。     

牛顿第二定律实验的改进

牛顿第二定律的验证是大学物理实验中的一个基础性实验．它是一个验证性实验，涉及到检验一个物理定律或规律的基本途径和方法．因此对于其实验精度往往有特殊的要求．本文先简要地分析一下现行高校中牛顿第二定律验证实验的方法，然后对其做了一些改进，改进后的实验精简了实验器材，提高了实验精度．     

阿基米德原理实验的改进

利用常用实验器材和生活材料自制了阿基米德原理演示了装置，叙述了制作方法和操作过程。     

高考物理实验拓展性复习探讨--以"描绘小灯泡伏安特性曲线"实验为例

高考试卷中几乎每年出现“拓展性”实验题，它们是以高中物理课本实验为基础，命题者通过改变课本实验的目的、原理、方法、器材、要求、情景等手段，对课本实验进行拓展翻新后设计的新的实验问题．这类试题不但考查实验基本知识与技能，而且特别注重考查实验知识技能的迁移能力和创新能力，这就要求我们在高考实验复习中，不仅要重视     

伽利略的自由落体定律研究——"最美丽"的十大物理实验之一

在伽利略的运动学研究中,自由落体运动是一个重要课题.他敏锐地认识到,通过打开自由落体运动这个缺口,会导致一门新科学的诞生.他在《两门新科学》(即《关于两门新科学的数学证明的对话》)一书中写道:"我的目的,是要阐述一门崭新的科学,它研究的却是非常古老的课题.也许,在自然界中最古老的课题莫过于运动了.     

基于嵌入式系统的发射度测量仪

基于嵌入式系统的发射度测量仪采用法拉第筒测量方法,数据采样率达到200 kHz,设计有7个不同的电流采样量程。讨论了发射度测量仪的系统构成和工作原理,详细介绍了其数据采集系统的设计与制作。通过选用高速、低噪声的集成电路芯片并组合适当大小、适宜材料的电阻和电容构建模拟链路,贯穿于整个模拟链路的滤波设计和低噪声的模拟电源技术及屏蔽防护技术都保证了低噪声采集电路的实现。实验测试表明:在量程为10 nA时,该测量仪测量精度为1.47%,量程1 000 nA时则达到0.32%;采样20 kHz的正弦波信号失真度为6.5 dB;运动精度为1.25 m时,运动速度最高3.125 mm/s。     

高师"中学物理教材教法与实验"课程改革探讨

中学物理教学法是一门综合性的应用学科，是高等师范院校物理专业的一门必修课．它是以国家教育方针为依据，以物理学为基础，综合地运用教育学、心理学、哲学等学科的一般原理来研究中学物理教学的理论和实践的学科．师范专科学校开设此课程的目的，是研究整个初中物理教学基本规律和从教的技艺，为培养合格的初中物理教师服务．     

"最美丽"的十大物理实验给我们的启示

美国纽约大学石溪分校哲学系的教员、布鲁克海文国家实验室的历史学家罗伯特·克瑞丝最近在物理学家中作了一次调查,要求他们提名历史上最美丽的实验,2002年9月份出版的《物理学世界》刊登了排名前10位的最美丽的物理实验.     

"摩擦力"演示实验的改进及应用

在现行高中物理课本第一册第一章第四节"摩擦力"中,用到了如图1所示的实验装置.但是由于受器材本身的限制,实验往往达不到预期的效果,因而笔者在教学中对该实验装置进行了改进,并进一步扩大了其应用范围.     

从“0维”到“10维”——物理世界的奇妙景观

引言 人们面对3维(Dimension)没有任何麻烦.我们接受固态物体和无界限空间的3维世界几乎从无别的想法,但接受时间为第4维则稍有困惑.当我们开始探查包含更多维度或真的少于3维的世界时,棘手的问题就来了.     

Ten theorems about quantum mechanical measurements

The aim of quantum mechanics is to explain macroscopic, objectively recorded phenomena. Microscopic objects are measured by enabling them to interact with a macroscopic measuring apparatus prepared in a metastable state. Macroscopic objects, such as cats, are not above the laws of quantum mechanics, but owing to their enormously dense level spectrum other aspects than single eigenvalues and eigenfunctions are prominent. These aspects can be described in classical terms, such as probabilities instead of probability amplitudes. The measuring act is fully described by the Schrödinger equation for object system and apparatus together. The collapse of the wave function is a consequence rather than an additional postulate. A model is constructed to demonstrate these statements. It also appears that the entropies of the object system and the apparatus increase by the same amount, namely the entropy difference between the metastable initial state and the stable final state of the apparatus.     

Ten years of CR physics with PAMELA

The satellite borne Pamela instrument is dedicated to the precise and high statistics study of CR fluxes on a four decades energy range. Pamela experiment is the last step of the “Russian-Italian Mission” (RIM) program established in 1992 between several Italian and Russian institutes and with the participation of Sweden and Germany. Designed as a cosmic ray observatory at 1 AU, it extensive program is made possible thanks to the outstanding performance of the instrument, the low energy threshold, the quasi-polar orbit and the 10 years duration of the observation. The physics program pays particular attention to the study of particles and antiparticles fluxes and includes search for dark matter, primordial antimatter, new matter in the Universe, study of cosmic-ray propagation, solar physics and solar modulation, and terrestrial magnetosphere. Very important is the discovery of the anomalous increase of the positron flux at energies higher that 50 GeV (the so called “Pamela anomaly”), and the abrupt spectral hardening of H and He, challenging the current paradigm of cosmic-ray acceleration and propagation in the Galaxy.     

Critical Points and Phase Transitions

Journal of Experimental and Theoretical Physics - Various critical phenomena and critical points appearing in many-particle systems under the variation of external conditions (fields), including...     

Ten Approaches to Define the Field Emission Area

Technical Physics - The emission area is one of the main parameters of field emission systems. A variety of formal determination techniques for the emission area is studied. Using the model...     

Corona Discharge Ion Mobility Spectrometry of Ten Alcohols

利用电晕放电离子源离子迁移谱装置对十种醇类有机物的迁移谱进行了研究. 在质子化的水合氢离子为反应离子和纯净空气为迁移气体的条件下,各种醇类有机物在其离子迁移谱中都获得了不同的产物离子峰. 利用指数稀释法得到各种样品的检测限在几个pmol/L量级. 利用所得到的离子迁移谱,以硬球碰撞为模型,得到了大气压下离子-分子相互作用的多个化学物理参数,包括离子分子碰撞、扩散系数、碰撞速率常数和离子半径.     

Critical Points and Supersymmetric Vacua I

Supersymmetric vacua (universes) of string/M theory may be identified with certain critical points of a holomorphic section (the superpotential) of a Hermitian holomorphic line bundle over a complex manifold. An important physical problem is to determine how many vacua there are and how they are distributed, as the superpotential varies over physically relevant ensembles. In several papers over the last few years, M. R. Douglas and co-workers have studied such vacuum statistics problems for a variety of physical models at the physics level of rigor [Do,AD,DD]. The present paper is the first of a series by the present authors giving a rigorous mathematical foundation for the vacuum statistics problem. It sets down basic results on the statistics of critical points s=0 of random holomorphic sections of Hermitian holomorphic line bundles with respect to a metric connection , when the sections are endowed with a Gaussian measure. The principal results give formulas for the expected density and number of critical points of fixed Morse index of Gaussian random sections relative to . They are particularly concrete for Riemann surfaces. In our subsequent work, the results will be applied to the vacuum statistics problem and to the purely geometric problem of studying metrics which minimize the expected number of critical points.In homage to Freeman DysonResearch partially supported by DOE grant DE-FG02-96ER40959 (first author) and NSF grants DMS-0100474 (second author) and DMS-0302518 (third author).     

寻找解题的“切入点”

在解难度稍大、综合性稍强的物理综合题时,常听到有些同学抱怨"一头雾水"、"无从下手",甚至在高考大题上一片空白,留下终生遗憾,究其原因,是未找准解题的"切入点",俗话讲"良好的开端,是成功的一半"、"入门即不难",可见解题时选准切人点是解题的基础和关键,切人的策略可有以下几个方面.