Table of Content

    13 April 2021 Volume 40 Issue 4
    Some thoughts on teaching solid state physics II: an example of the frontiers in magnetism
    YUAN Zhe
    College Physics. 2021, 40(4):  1-5.  doi:10. 16854 /j. cnki. 1000-0712. 200451
    Abstract ( 638 )   PDF (452KB) ( 339 )  
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    Solid state physics is an important course for undergraduate students of physics,and its contents are

    closely related to the research frontiers of condensed matter physics. Introducing appropriate latest progress in the

    teaching can expand students’scientific level and encourage them to pursue further studies and researches. In this

    paper,domain-wall resistance in ferromagnetic metals in the chapter of magnetism in solid states is taken as a typical

    example and a guidance for students is provided to analyze the spin dependent transport in magnetic domain

    walls. In this process, the students need to integrate the knowledge they have learned including the energy band theory,

    perturbation theory and transport phenomena in quantum mechanics and solid state physics. By systematically illustrating

    this typical example, the integration of the cutting-edge research of spintronics into teaching solid state

    physics is demonstrated which would be a useful reference for creating a high -level, innovative and challenging

    course of solid state physics.

    A more general proof on“Nuclear reaction being completely inelastic collision when incident particle having threshold energy”
    SU Guo-zhen
    College Physics. 2021, 40(4):  6-7.  doi:10. 16854 /j. cnki. 1000-0712. 200221
    Abstract ( 603 )   PDF (218KB) ( 171 )  
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    A more general proof on“Nuclear reaction being completely inelastic collision when incident particle having threshold energy”is presented.
    The characteristic derivation method of Maxwell s rate distribution
    FENG Shi-meng
    College Physics. 2021, 40(4):  8-10.  doi:10. 16854 /j. cnki. 1000-0712. 200485
    Abstract ( 1085 )   PDF (253KB) ( 381 )  
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    A basic point in college physics teaching is to cultivate students' spatial imagination. Maxwell's rate

    distribution law is a central content of the gas molecule kinetic theory,which is difficult for students to learn and

    professors to teach during the teaching process of gas dynamics theory. Its formula is abstract,complicated and difficult

    for students to understand. Based on the concept of velocity space, it is presented the surface area of the velocity

    sphere is equivalent to the number of microscopic states of a single gas molecule,and the Langerian function is used

    to derive the velocity distribution function of gas molecules in the ideal gas equilibrium state. This method is relatively

    simple and easy for students to understand is helpful to cultivate their spatial imagination.

    The influence of atomic mass on the dispersion relation of one-dimensional three-atom chain
    ZHAO Yuan, HU Jian-min, WANG Yue-yuan, NIU Li
    College Physics. 2021, 40(4):  11-14.  doi:10. 16854 / j. cnki. 1000-0712. 200407
    Abstract ( 815 )   PDF (737KB) ( 109 )  
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    In this paper,the numerical analysis method is used to study the influence of the atomic

    mass in the primitive cell on the dispersion relationship of one-dimensional three- atom chain.

    The basic law of the spectral width and the frequency band gap changing with the atomic mass are established. The results show

    that when the mass of only one atom in the primitive cell changes,the width of the acoustic wave spectrum decreases with the increase

    of any atomic mass. The spectral width of optical waves increases with the increase of the mass of small atoms,and decreases with the increase of the mass of large atoms. Both frequency band gaps are narrowed with increasing the mass of the small atom,and widened with increasing the mass of the large atom. As the mass of the intermediate atoms increases,the frequency forbidden band between low-frequency optical waves and acoustic waves gradually is narrowed,while the frequency forbidden band between high-and low-frequency optical waves is gradually widened. The rel-evant results provide a theoretical basis for the design of crystal band-pass filters.

    Design of a horizontal Young's modulus instrument and assembling a platform scale
    LI Cheng-long, CHANG Fang-jin, SHOU Hua-jie , SHEN Qi-kai
    College Physics. 2021, 40(4):  15-18.  doi:10. 16854 /j. cnki. 1000-0712. 200015
    Abstract ( 666 )   PDF (699KB) ( 96 )  
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    Based on the stress analysis of steel wires placed horizontally,the measuring formula

    of the young's modulus is derived,and then it is measured experimentally. Using the value of

    young's modulus as a known parame- ter and steel wire as a strain sensor of the pressure,a simple

    platform scale is designed and its measuring formula is derived to measure the gravity of unknown

    object. Such a design makes the traditional confirmatory experiment im- prove to a designing

    experiment,reduces the experimental error and also enriches the experiment contents.

    Analysis of liquid equilibrium state under the rotating mode
    LEI Yi, SHI Li-hong, ZHANG Jun-cheng, PAN Jian-peng
    College Physics. 2021, 40(4):  19-21.  doi:10. 16854 / j. cnki. 1000-0712. 200143
    Abstract ( 619 )   PDF (585KB) ( 131 )  
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    This paper studies equilibrium liquid level formed by the rotation of liquid on the

    wall,the equation is deduced when the slop of the wall is K ( K≠0) . When K→∞ ,the change of liquid

    level is infinite with the in- crease of rotating speed,but the rise height of liquid level is

    equal to the fall depth of liquid level,and the volume relationship is a constant. when K>0,the

    container is a round table with large top and small bottom. The liquid level

    change caused by rotating paraboloid is limited,and the limit value is槡3 +1,when the liquid

    rotation angular veloci- ty exceeds the critical angular velocity,the rotating liquid surface

    is divided into two parts: the paraboloid in the middle and the water film with growing edge.

    A double-beam interference apparatus with a regular triangle structure
    ZHOU Guo-quan
    College Physics. 2021, 40(4):  22-26.  doi:10. 16854 / j. cnki. 1000-0712. 200135
    Abstract ( 1333 )   PDF (557KB) ( 382 )  
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    An optical interference apparatus with a regular triangle structure,which can

    generate double - beam interference,is introduced according to the optical wave theory. The

    formulae of optical path difference and phase difference have been derived; the

    interference conditions and distribution laws of spots or fringes are also quantitatively

    analyzed in detail. Its possible application and supplement function in teaching and researching

    activ- ities are also discussed.

    Terahertz spectral analysis of emulsion combined with effective medium theory
    LI Chao, QIN Fan-kai, MENG Zhao-hui, CHEN Ru, YANG Qi,
    College Physics. 2021, 40(4):  27-31.  doi:10. 16854 / j. cnki. 1000-0712. 200314
    Abstract ( 660 )   PDF (1477KB) ( 100 )  
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    Crude oil emulsions have an important influence on the long-distance transportation of crude oil. The oil and water state of the emulsion and the interaction mechanism require new theories and new methods. The terahertz spectrum ( THz- TDS) response of

    crude oil emulsion is studied based on the effective medium theory. The THz-TDS of emulsions with water content of 0 ~ 28 % are obtained by using the THz-TDS system. The optical parameters such as absorption coefficient and dielectric constant are calculated by

    Fourier transform. The optical parameters increase with the increase of water content of emulsions. The actual dielectric constant is consistent with the dielectric constant calculated by Bruggeman's theory,and the maximum error rate is less than 3 % . The results show that when the

    water content is small,the water is dispersed in the crude oil,the distance between the particles is large,and the interaction force between the particles is small. As the water content increases,the water phase and the oil phase are mixed and distributed,the distance between the

    particles will become smaller,and the inter- action force of the particles will become larger.Therefore,the effective medium theory is significant to investigate the THz spectrum of oil-water emulsions.

    A practical exploration of the teaching mode of PAD class in college physics
    QIN Dan, XING Juan, LI Guang-zhong, HUA Gui-yuan, ZHAN Libo, YAN Peng
    College Physics. 2021, 40(4):  32-36.  doi:10. 16854 / j. cnki. 1000-0712. 200276
    Abstract ( 555 )   PDF (353KB) ( 161 )  
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    With the change of social demand for talents,many colleges and universities revise the

    talent train- ing program in combination with the professional competence training. The changes

    of class hours and learning situ- ation make it difficult for the traditional physics teaching mode in university to effectively guarantee the quality of talent cultivation. In this paper,in view of the existing problems in teaching,the PAD ( Presentation-Assimilation

    -Discussion) Class teaching mode is used to reform the teaching of college physics course and a number of teaching

    measures is proposed,involving course content,learning objectives,teaching activities,teaching evaluation,etc.

    A questionnaire is employed to evaluate the teaching effect. A follow-up reform scheme is also proposed according to the teaching reflection.

    Thinking and practice of ideological and political construction of electrodynamics course
    LIU Xiao-jun, ZHANG Xin-yue
    College Physics. 2021, 40(4):  37-39.  doi:10. 16854 / j. cnki. 1000-0712. 200251
    Abstract ( 1034 )   PDF (120KB) ( 268 )  
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    At present carrying out the ideological and political construction of professional

    courses is an impor- tant research problem in education field. In this paper,the

    electrodynamics course in physics major is combined with the research and the practice of

    ideological and political courses construction. The contents and characteristics of this course

    are organically combined,and the elements and some entry points of ideological and

    political con- struction of courses are deeply excavated. Through teaching practice,some

    preliminary effects are obtained which should play an active role in learning and promoting the

    ideological and political construction of science courses. It can make the curriculum education

    realize and also uses the course to its full play. At last,some summary and prospect

    are put forward.

    The exploration of ideological and political teaching in the course of the history and methodology of physics
    ZHANG Xiao-lei, ZHANG Le, ZHANG Yu-yi, BIAN Ya-jie, YIN Ya-ling
    College Physics. 2021, 40(4):  40-44.  doi:10. 16854 / j. cnki. 1000-0712. 200340
    Abstract ( 888 )   PDF (207KB) ( 209 )  
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    In this paper,the course of the History and Methodology of Physics in East China Normal

    Universi- ty is taken as a research object. Based on the integration of science and

    humanities,the fundamental task of strengthening morality education is expected to be realized

    and the targets of imparting professional knowledge,re- solving doubts,propagating the doctrine and

    educating people is met by applying ideological and political ideas to traditional classroom

    teaching. What studied in this paper could have a certain reference value for the science

    de- partments in university to carry out the construction of course-based ideological and political


    Construction and practice of college physics course under the background of new engineering
    WANG Xiao-ou, ZHANG Ling-li, YUAN Cheng-xun, WANG Xian-jie, JIN Chen-fei, ZHANG Yu
    College Physics. 2021, 40(4):  45.  doi:10. 16854 / j. cnki. 1000-0712. 200412
    Abstract ( 598 )   PDF (837KB) ( 144 )  
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    As an important basic course for engineering specialty,college physics plays an

    irreplaceable role in the development of new engineering education and the cultivation of

    interdisciplinary talents with international competitiveness. In the autumn of 2018,the physics

    teaching and research office of Harbin institute of technology had carried out a comprehensive

    and in-depth reform on the curriculum system,teaching content,teaching mode and other

    aspects in accordance with the new requirements of talent training for new engineering

    construction. After nearly two years of teaching practice,good results have been achieved.

    Visualized teaching of college physics based on modern information technology
    QIN Fang-li
    College Physics. 2021, 40(4):  50.  doi:10. 16854 / j. cnki. 1000-0712. 200200
    Abstract ( 579 )   PDF (1567KB) ( 137 )  
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    Modern information technology provides many tools to realize visualized college physics

    teaching. In this paper,some examples are given to show how these tools,such as numerical

    simulation,mobile phone,modern intelligent equipment,animation production platform,made the

    teaching of college physics visualized. The visualized teaching of college physics can improve

    the students' interest in learning. This paper presents a reference for the

    visualized classroom teaching of college physics.

    Online teaching design and practice of college physics based on “One center,three stages,six principles and three examinations”
    JIANG Hai-li, ZHAO Wen-hui, MENG Ting, ZHAO Yan-cheng, SUN Qiu-hua, LIU Yan-lei
    College Physics. 2021, 40(4):  53.  doi:10. 16854 / j. cnki. 1000-0712. 200247
    Abstract ( 542 )   PDF (4105KB) ( 88 )  
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    This article is aimed at the exploration and practice of online teaching design of

    college physics. Rel- ying on the teaching platforms,such as Rain Classroom,Zhihuishu etc. ,the

    student training process based on auton- omous learning is constructed in college physics online

    course in our university. It has three stages,including preview before class,flipped classroom and

    after class consolidation,and realized co-oriented education,precise teaching, gradual

    progression,open discussion,independent thinking and whole-staff interaction. Furthermore,the

    course is examined and promoted by platform data,supervision,students’feedback and

    teachers’mutual evaluation. Over- all,the online intellectual teaching based on autonomous

    learning is featured by “one center,three stages,six principles and three examinations”.

    Practice results have shown that this teaching design has promoted the conver- sion from separation

    to integration of in and after class teaching relying on internet information technology.

    Experience summary and effect analysis ofcollege physics online teaching
    XU Yi-shuang¹, WANG Gang¹, XU Jie¹, MU Chun-yan¹, LI Hui¹, YANG Guang-wu²
    College Physics. 2021, 40(4):  60.  doi:10. 16854 / j. cnki. 1000-0712. 200369
    Abstract ( 973 )   PDF (1047KB) ( 182 )  
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    Based on the modularity idea,teaching links are designed in seven steps to strengthen

    classroom in- teraction,the cultivation of students' ability to apply knowledge,and ideological and

    political education. The com- bination of Tencent Classroom and Cloud Class is used for live

    network teaching. Classroom management adopted multiple models,such as inviting counselors

    to co-manage,introducing fault-tolerant mechanism,paying attention to students' emotional changes

    and other measures to improve students' participation in the classroom. The average attendance

    rate reaches 98% . The examination is based on the Super Star Learning Pass and is

    conducted in the form of open-book examination with a large number of questions. By comparing

    the students' scores of offline exam- ination in recent three years with that of the online

    examination of this semester,it is found that the distribution of students' scores of this semester

    is more reasonable,which indicates that online teaching has certain advantages.

    The motion equation,period and position probability distribution of three-line pendulum
    WU Ming-jue, WANG Shun-yu, LI Jun, XIA Xue-lian, ZHANG Li-hua
    College Physics. 2021, 40(4):  64.  doi:10. 16854 / j. cnki. 1000-0712. 200296
    Abstract ( 1841 )   PDF (434KB) ( 524 )  
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    In this paper,based on the Lagrange equation of conservative system,the

      differential equation of three-line pendulum in large swing angle motion and the

      approximate treatment method of linear vibration with small swing angle are given. Under

      the approximate condition about the structural dimensions of the three-line pen- dulum,the motion

      differential equation,period and position probability density distribution of the three-line

      pen- dulum under two different conditions of large swing angle and small swing angle are discussed.

    A stochastic dynamics model for the directional transport of kinesin
    YANG Zi-bei, QIU Xing, CHEN Qiao-ni, WANG Hai-yan
    College Physics. 2021, 40(4):  68.  doi:10. 16854 / j. cnki. 1000-0712. 200244
    Abstract ( 724 )   PDF (650KB) ( 157 )  
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    In this paper,we consider the chemical-mechanical coupling of the kinesin in an

    asymmetric peri- odic potential during stepping. Based on Brownian motor theory,we numerically

    simulate the motion characteristics of kinesin under certain experimental conditions by MATLAB.

    Firstly,we simulate the image of the displacement and velocity changing with time of a

    single kinesin. Then we respectively calculate the average speed of several ki- nesin. Finally we

    calculate the ensemble average of the speed of kinesin under different loads. The simulation

    re- sults show that kinesin has waiting state and walking state in directional motion,the walking

    step is about 8. 2 nm, and the motion has certain randomness. Comparing with the experimental

    results,it is found that the calculated re- sults of the model are in good agreement with the

    experimental results.

    Exploration of the deceleration process of gyroscope in magnetic field starting from a simple model
    FENG Xin, FAN Hong-jie, CHENG Yu-kun, ZHAO Wei, TAO Xiao-ping, PU Qi-rong, ZHAO Xia, ZHANG Zeng-ming
    College Physics. 2021, 40(4):  72.  doi:10. 16854 / j. cnki. 1000-0712. 200254
    Abstract ( 749 )   PDF (1763KB) ( 185 )  
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    The 12th problem of 2019 China Undergraduate Physics Tournament ( CUPT) was to study the de- celeration of a gyroscope made of nonferromagnetic conductor materials when placed in a magnetic field. There is no specific parameter to be qualified in the question,which is difficult to be solved comprehensively and uniformly by Maxwell’s equation. Starting from the infinite long conductor cylindrical model in this paper,the formulae of elec- tromagnetic resistance moment depends on magnetic induction strength,angular velocity,conductivity,and other parameters are obtained. The deriving process of these formulae is going under the condition that the direction

    of the magnetic field is vertical or parallel to the gyroscope’s shaft with reasonable

    approximation. Then the general rela- tion of gyroscope deceleration damping coefficient is given

    when the direction of the magnetic field is relative to any

    direction of the gyroscope’s shaft with the rationality verified through the dimensional analysis.

    In the experimental part,an experimental facility driven by a DC motor is designed,and the

    analysis of measurement data shows that the formulae of the electromagnetic resistance moment

    obtained from the basic model can describe the actual gyro- scope deceleration process more


    Simulation and research on thermal lens effect of low power laser
    GUO Zheng-xin¹, GAO Qi-ni¹, FAN Zi-ping¹, CHEN Qing-nan¹,
    College Physics. 2021, 40(4):  79.  doi:10. 16854 / j. cnki. 1000-0712. 200306
    Abstract ( 495 )   PDF (1647KB) ( 89 )  
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    Comparing with high-power laser,low-power laser is safer and its thermal lens effect is

    more sen- sitive to the change of laser power,so it is more suitable for experimental teaching. In

    this paper,the thermal lens effect of low-power laser is simulated by using the finite element

    method,namely,the temperature field of the me- dium and the focal length of the equivalent thermal

    lens are simulated,and the relationship between the focal length of low-power laser and the laser

    power as well as the thermal absorption rate and thickness of the medium is quanti- tatively

    explored. The simulation results are in good agreement with the experimental data,which provides a

    theo- retical basis for exploring the thermal lensing effect of low-power laser.