对一道中学生物理竞赛试题答案的商榷

重新解答了第26届全国中学生物理竞赛复赛第3题第1小题,指明了该题的参考解答(标准答案)错误.     

一道高考题的新解法

2011年陕西、山西、宁夏等省、自治区高考使用新课程理综卷,物理题延续了往年的稳定,又体现了"稳中有新,稳中有进".第24题是物理力学解答题,该题贴近生活,注重学以致用,主要考查考生对物理定律的基本应用能力,考查考生的分析综合能力,也是对物理模型的建立和应用的考查.该题常规解法     

对2011年两道高考物理实验题形成过程的质疑

在2011年的高考物理实验题中有两道的实验数据和结果与实事不符,题的形成没有以实验事实为依据,有杜撰嫌疑.下面就此二题进行说明.【例1】[2011年高考广东卷理综第34题第(2)小题]在"描绘小电珠的伏安特性曲线"实验中,所     

如何用量筒和音叉测定声波的波长

中师物理教材"声音的共鸣"一节的练习中有一道实验题:用量筒和音叉测声波的波长.题的意图是让学生根据本节实验的结论:"空气柱跟某声波发生共鸣的最小长度等于该声波波长的1/4"来测定声波的波长.     

用“数形结合”的思维方法巧解2013年高考物理压轴题

2013年高考全国理综卷(适用于广西)物理部分最后一题,是一道推陈出新、独具选拔功能的创新题,在涉及高中物理的主干知识的同时,既考查学生用物理知识及其规律分析相关问题的能力,又考查学生运用数学知识解决物理问题的能力(包括作图能力),是符合新课改思想和锤炼物理思维的好题.但在命题组给出的参考解答中却体现如下4个特     

对2014年高考理综卷(课标卷Ⅱ)第21题的评析和思考

对2014年高考(课标卷Ⅱ)理综试卷物理学科的选择题的第21题进行来了分析,就该题的创新性、科学性和严谨性展开了探讨,并提出了笔者的几点见解和建议.     

PDCA引导下的CUPT科研先修训练

以2018年CUPT赛题"粉末的颜色"为例,介绍了PDCA工作方法在CUPT竞赛中的应用.将PDCA工作方法移植到CUPT和科研项目训练,可以将PDCA改为设计实验方案(Plan)、实验现象表征(Do)、理论模拟验证(Check)和物理机制阐述(Analysis).通过PDCA闭环方式,培养学生自主学习和提升创新能力,让学生由"答案引导式"的被动思维过渡到"项目引导式"的创新思维模式.将CUPT赛题作为科研先修训练的有效手段,可以为学生今后高阶段科研工作奠定良好的学习基础.     

复习教学中“一题多解”策略的运用

"一题多解"不是盲目地追求物理问题的多解,更不是学生或教师炫耀自己的解题能力.在笔者看来,"一题多解"作为高中物理总复习期间的一种复习策略,如果运用恰当,对夯实学生物理基础知识和方法,提高学生分析解决物理问题的能力大有裨益.在复习的不同阶段,应该采取不同类型的"一题多解"策略.在第一轮复习中,我们更关注学生对基础物理知识和基本方法的掌握,不急于要求学生从整体上把握高中物理知识体系.所以,针对第一轮复习的特点,我们应多采取"知识点"内的"一题多解"策     

吹泡泡中的学问

"吹泡泡"是儿童喜爱的游戏.第十七届全国初中应用物理知识竞赛第三题的第4小题,就是取材于"吹泡泡",对我们熟悉的现象与物理知识做了很好的融合,考查灵活运用所学物理知识、方法和处理实际问题的能力.     

近四年高考物理关于“电阻测量”实验题的分析与启示

纵观近四年的高考物理实验题,可以发现:每年都有一道题是围绕着"电阻的测量"而展开的,但都不是简单地考查课本内容,而是通过改造、组合、引伸,不断地更新物理背景,改变设问角度,使题目充满了新意.与以往教学中的一些典型的陈题相比,这些实验题更注重考查对实验原理、实验方法的理解和应用,更注意考查学生对知识的灵活运用能力和创造性解决问题的能力.下面试作具体分析.     

Twist-Deformed Gravitational Quantum Well

In this article we define the gravitational quantum well model on twist-deformed space with two spatial directions commuting to time-dependent function f_κ(t). Further, we find the corresponding energy spectrum and by its comparision with the GRANIT experiment predictions, we obtain bounds on the noncommutativity function in the case of two first energy levels.

     

有机量子阱发光的研究

有机量子阱具有优异的光电性能,在光电子器件中有广泛的应用.论述了如何证明有机量子阱的存在及其国内外研究现状,介绍了有机量子阱在有机电致发光中的应用以及存在的问题,重点是如何利用有机量子阱提高发光性能,并指出了今后的研究方向.     

Well Posedness for Pressureless Flow

We study the uniqueness problem for pressureless gases. Previous results on this topic are only known for the case when the initial data is assumed to be a bounded measurable function. This assumption is unnatural because the solution is in general a Radon measure. In this paper, the uniqueness of the weak solution is proved for the case when the initial data is a Radon measure. We show that, besides the Oleinik entropy condition, it is also important to require the energy to be weakly continuous initially. Our uniqueness result is obtained in the same functional space as the existence theorem. Received: 26 September 2000 / Accepted: 25 April 2001     

Phonons in Quantum-Dot Quantum Well

Phonon modes of AlAs/GaAs/AlAs and GaAs/AlAs/metal Pb quantum-dot quantum wells (QDQW‘s)with the whole scale up to 90 A are calculated by using valence force field model (VFFM) based on group theory.Their optical frequency spectra are divided into two nonoverlapping bands, the AMs-like band and the GaAs-like band,originated from and having frequency interval inside the bulk AlAs optical band and bulk GaAs optical band, respectively.The GaAs-LO (F)-like modes of QDQW‘s that have maximum bulk GaAs-LO (F) parentages in all modes covering the whole frequency region and all symmetries have always A1 symmetry. Its frequency is controllable by adjusting the structure parameters. In AlAs/GaAs/AlAs, it may be controlled to meet any designed frequency in GaAs-like band.The results on GaAs/AMs/metal Pb QDQW‘s show the same effect of reducing in interface optical phonons by using the metal/semiconductor interface revealed ever by macroscopic model. The frequency spectra in both GaAs-like and AlAs-like optical phonon bands are independent of the thickness of Pb shell as long as the thickness of Pb shell is no less than 5 A. Defects at metal/AlAs interface have significant influence to AMs-like optical modes but have only minor influence to GaAs-like optical modes. All these results are important for the studying of the e-ph interaction in QD structures.     

Current-Enhanced Quantum Well Solar Cells

We present the experimental results that demonstrate the enhancement of the short-circuit current of quantum well solar cells. The spectral response shows that the introduction of quantum wells extends the absorption spectrum of solar cells. The current densities under different truncated spectrums significantly increase, showing that quantum well solar cells are suitable to be the middle cells of GalnP/GaAs/Ge triple-junction solar cells to increase their overall conversion efficiency.     

Carrier Dynamics in Quantum Well Lasers

A fully microscopic theory is used to perform an analysis of carrier–carrier and carrier-LO phonon scattering in semiconductor quantum wells, focussing on the high-density case relevant for laser structures. A large variance of scattering times is observed depending on the material parameters, apparently contradicting popular belief in some cases. For instance, carrier–carrier scattering may slow down when the carrier density is increased. Electron-hole scattering times are found to be on the same order of magnitude as carrier-phonon scattering, making the introduction of a separate electron and hole temperature necessary. Heating by optical pumping is investigated and plasma cooling is shown to be possible by optical pumping of the laser structure.     

Morse势阱中的光检波效应

利用量子力学中的密度矩阵算符理论和迭代方法，得到Morse势阱中的光检波系数的解析表达式。并以典型的GaAs/AlGaAs莫尔斯量子阱为例进行数值计算。研究结果表明，较大的光检波系数与系统的非对称性有关，系统的非对称性越大，光检波系数越大。