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Table of Content

    20 November 2018 Volume 37 Issue 11
      
    Innovating simultaneously for thinking,content and method in physical education
    WANG Zu-yuan,GU Mu
    College Physics. 2018, 37(11):  1-3.  doi:10.16854 /j.cnki.1000-0712.180499
    Abstract ( 1583 )   PDF (177KB) ( 660 )  
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    Through the example of the finals Lecture Competition for Young Teachers of the National Physics Foundation Course in Higher Education (LCYTNPFCHE) held in Guizhou University in 2018,the authors introduce the purpose and significance of the LCYTNPFCHE,as well as the influence for the national physics foundation course teaching. The lecture competition is jointly sponsored by the Higher Education Teaching Guidance Committee (HETGC) of the Ministry of Education for University Physics,Physics Major,and the Physics Teaching Committee of the Chinese Physical Society (PTCCPS). And it is co-sponsored by the Higher Education Press and the Science Press. By presenting the grand occasion of the National Annual Symposium on the Education of Physics Foundation Courses in Higher Education co-sponsored by the HETGC and the PTCCPS,this paper highlights the impact of the Symposium on the reform and construction of the national basic physics courses,such as“College Physics”and“College Physics Experiment”.
    Hellmann-Feynman theorem based on ensemble average
    CHEN Li-hua1,FAN Hong-yi 2
    College Physics. 2018, 37(11):  4-5.  doi:10.16854 /j.cnki.1000-0712.180209
    Abstract ( 1982 )   PDF (141KB) ( 494 )  
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    The paper discusses how to extend the Hellmann-Feynman (H-F) theorem,which is just suitable for the pure state average,to the case of mixed state as ensemble average. Some applications of the generalized H-F theorem are presented.
    Derivation and application of the transformation matrix of unit vector
    LIU Chun-ping
    College Physics. 2018, 37(11):  6-8.  doi:10.16854 /j.cnki.1000-0712.180083
    Abstract ( 2065 )   PDF (144KB) ( 514 )  
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    The transformation matrix of unit vector in the orthogonal curvilinear coordinate system is derived firstly by using compound function derivation law and vector algebra knowledge. Then the computational formulas of the spatial derivative,time derivative of unit vector and the velocity,acceleration of particle are given through the transformation matrix
    A paradox on the perpetual motion of semipermeable membrane
    LI Li-ben,WANG Hui,LI Tong-wei,WANG Zhao-wu,TA Ming-cong,LI Guo-ling
    College Physics. 2018, 37(11):  9-12.  doi:10.16854 /j.cnki.1000-0712.180131
    Abstract ( 2800 )   PDF (318KB) ( 1366 )  
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    The pipe filled with 3% sugar solution and closed by the semipermeable membrane at its bottom is inserted into a large pool filled with pure water. For the semipermeable membrane-solution system,the solution level will be about 22 meters higher than the pure water level. A double semipermeable membrane-solution system is structured by the pipe added another semipermeable membrane in the middle (such as 10 m from the bottom). Is there the level of pure water in the pipe higher than the level of the water in the pool? Thermodynamic analysis shows that which is not possible for the case of the equilibrium solution and will be possible for the uniform solution. But the latter case does not violate the second law of thermodynamics.
    Energy eigenvalues of particle bounded in the polynomial potential
    WU Feng,XU Ning
    College Physics. 2018, 37(11):  13-15.  doi:10.16854 /j.cnki.1000-0712.180203
    Abstract ( 1370 )   PDF (235KB) ( 399 )  
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    We present a simple scheme to calculate the energy eigenvalues of particle bounded in the polynomial potential by using the linear variational method. The wave functions of the harmonic oscillator (HO)including one parameter are chosen as the basis functions,and the general formula of the Hamiltonian matrix element (HME) of coordinate operator for the HO is utilized. The algebraic expression of the system’s HME is derived. The HO parameter is determined from the rule that the trace of the Hamiltonian matrix takes the minimum value relative to this parameter.
    Study of analysis and acquisition method of nonlinear harmonic in three-phase transformer
    SUN Dian-ping,ZHAO Qiang,GUO Chao-xiu
    College Physics. 2018, 37(11):  16-20.  doi:10.16854 /j.cnki.1000-0712.170606
    Abstract ( 1220 )   PDF (1272KB) ( 541 )  
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    In this paper,both the current and the voltage in a transformer are measured by digital oscilloscope. The nonlinear relation between the current harmonic and the voltage is discussed via harmonic analysis,thereinto,the amplitude of three harmonic currents increase rapidly with the increase of the voltage,which is approximately proportional to the voltage to the third power,and the amplitude of the even harmonic current does not significant increase with the voltage. The experimental results are consistent with the theoretical analysis. In addition,three harmonic signals are obtained through different connection of winding in the three-phase transformer,and rule of the three times harmonic wave of the current changing with the voltage is studied.
    Investigation on experiments of acoustic resonance in tubes
    College Physics. 2018, 37(11):  21-23.  doi:10.16854 /j.cnki.1000-0712.180195
    Abstract ( 1381 )   PDF (686KB) ( 487 )  
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    Teaching experiments of acoustic resonance in tubes are bases not only to understand the physical phenomena of acoustic wave propagate,superposition and resonance,but also to understand the basic physic mechanism of measuring the sound absorption coefficient and acoustic impedance of materials. Some non-ideal conditions in this experiment can promote students to think further,and to understand the enhancement and attenuation of sound wave and its application in the field of industry. Measurement of the minimum resonant frequency,sound pressure distribution of waves and end corrections are investigated.
    Simulation teaching for amplitude-splitting thin film interference based on the Macleod software
    WANG Wen-liang1,RONG Xiao-hong2,CHENG Hua-ying1
    College Physics. 2018, 37(11):  24-27.  doi:10.16854 /j.cnki.1000-0712.180257
    Abstract ( 1730 )   PDF (1580KB) ( 382 )  
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    Amplitude-splitting thin film interference is an important content of the wave optics teaching in colleges and universities. It is also the theoretical basis of thin film optics. Based on the famous optical thin film simulation software Macleod,the constructive and destructive interference of wedge-shaped thin films are simulated by using the 3D drawing technique. The change of the phase of the light waves is simulated,as well as the multilayer structure with high reflective film and the anti-reflection film are also simulated. Let the students contact theory analysis with software simulation analysis,which will improve teaching effect because it make students understand amplitude - splitting thin film interference specifically and figuratively. It also enables students to understand the spectral regulation ability of optical thin films and its widespread application in the productive practice,so as to improve students' interest in learning.
    Research on the teaching method of fundamentals of solid state physics
    GUO Xing-yuan,LI Ping
    College Physics. 2018, 37(11):  28-31.  doi:10.16854 /j.cnki.1000-0712.180055
    Abstract ( 1889 )   PDF (168KB) ( 571 )  
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    Solid state physics is to understand how solid materials behave,the understanding of solid materials has gone through from the shape of the surface to the inner structure,from the large - scale properties of solid materials to their atomic -scale properties,from the qualitative analysis to the quantitative calculation,from the superficial phenomenon to the physical nature. We have taught solid - state physics over the course of this and summed up the following teaching experiences: using the phenomenological view to look at the solid state physics problems; figure out the internal logic relationship of the book between chapters and section; based on author’s research field,establishing the internal relation of frontier science and basic knowledge in solid state physics; traditionally and multimedia educational model to cooperate with each other; cultivating students’thinking ability by using after class homework. We hope this paper could provide new ideas and methods to make students gain a deep understanding of solid state physics.
    Investigation on the origin of several basic concepts in the early stage of electricity
    FENG Tian-shu
    College Physics. 2018, 37(11):  32-36.  doi:10.16854 /j.cnki.1000-0712.180088
    Abstract ( 2077 )   PDF (600KB) ( 1270 )  
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    This paper describes some experimental and ideological processes during the early development of electricity,such as capacitance,voltage,electromotive force and current. The discovery process of Ohm’s law is also described. The birth of these concepts and laws is hidden in the depth of history,and it is helpful for the teaching of electromagnetics to excavate and describe these historical processes.
    Special effects of several physics laws on the natural environment
    ZHAO Shi-hua1,ZHU Qin2,WANG Qi1
    College Physics. 2018, 37(11):  37-40.  doi:10.16854 /j.cnki.1000-0712.170586
    Abstract ( 1343 )   PDF (469KB) ( 574 )  
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    Via the discussion of air resistance,acoustic absorption and electromagnetic absorption,it is expounded that these common physical phenomena and laws are the basic conditions for existence of life on earth.
    Observation and analysis of two special phenomena in the experimental operation of sound velocity measurement
    SONG Zi-wu,WANG Mao-xiang
    College Physics. 2018, 37(11):  41-45.  doi:10.16854 /j.cnki.1000-0712.180110
    Abstract ( 2625 )   PDF (705KB) ( 665 )  
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    Sound velocity measurement is one of the basic contents of college physics experiments,and some special phenomena appearing in the process of practical operation are worth to discuss deeply. This paper studies mainly the two phase synthesis phenomena (i.e.,secondary wave phenomena) and proves its existence through concrete experimental measurement and gives a theoretical explanation according to the simulation numerical solution of Mathematica software. Based on the results,the principle of the resonant interference and phase comparison methods for measuring sound velocity is discussed. The asynchrony between the measurements is shown,and the qualitative explanation is given.
    Formation mechanism research and simulation of a laser ring induced by a thick metal wire
    FENG Yu,WANG Guang,ZHAO Min,LI Fo-sheng
    College Physics. 2018, 37(11):  46-51.  doi:10.16854 /j.cnki.1000-0712.160564
    Abstract ( 1747 )   PDF (2278KB) ( 558 )  
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    When a beam of laser irritates on a thick metal wire,a light ring will appear on the screen which lies vertical to the wire. In this paper,we analyze the formation mechanism of the ring,explore the influence of related parameters on the ring with computer simulation and experiments. It is shown that the proposed theory matches the experiments very well.
    A Monte-Carlo simulation tool to facilitate cosmic muon detections
    LUO Xin1,XU Yi-xin1,CAO Guang-jie2,TANG Jian1
    College Physics. 2018, 37(11):  52-57.  doi:10.16854 /j.cnki.1000-0712.180138
    Abstract ( 1697 )   PDF (958KB) ( 489 )  
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    A brief introduction to cosmic muon physics is presented. We focus on the basic principle of coincident counting of cosmic muons in the physics laboratory. We introduce the method of Monte - Carlo ( MC) simulation in particle physic,including selection of physics lists,optimization of detector materials and geometries,inputs and outputs of the simulated data. We also discuss the preliminary results muon decay spectra where the fitted muon life-time matches the theoretical prediction. The established MC simulation tool is of pedagogic significance for it helps better students’insight into the cosmic muon physics.
    Theoretical study of unparallel contact-mode triboelectric nanogenerators
    HUANG Mei-zhen1,ZHANG Tian-tian1,XIE Hong1,JIANG Tao2,WANG Zhao-na1
    College Physics. 2018, 37(11):  58-63.  doi:10.16854 /j.cnki.1000-0712.170559
    Abstract ( 1678 )   PDF (1303KB) ( 1866 )  
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    As an easy-come and clean way to harvest energy,triboelectric nanogenerators have demonstrated a high application value in small self-powered system and sensors. Especially,triboelectric nanogenerators with unparalel structure have been widely experimentally designed in the contact-mode.Here,a systematical theoretical study of unparallel contact-mode triboelectric nanogenerators was constructed based on the equivalent circuit model.The equivalent capacitance and the control equation for analyzing output chracteristics was derived for the unparalel structure cases.By numerical simulation,the relationship between output voltage,current,power and the moving trail was further studied.Finally,an experiment was designed to verify the obtained conclusions,demonstrating a high degree of consistency with the theory.The results may supply important theoretical basis for rational design of the triboelectric nanogenerators structure.