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    15 July 2025 Volume 44 Issue 6
      
    Exploring the physical mechanisms of piano sounding using smartphone
    College Physics. 2025, 44(6):  1.  doi:10.16854/j.cnki.1000-0712.240384
    Abstract ( 204 )   PDF (364KB) ( 192 )  
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    There is a complex physical mechanism behind the sounding of piano. The purpose of this paper is to explain the phenomenon of piano sounding using theoretical physic knowledge, and to measure frequency and amplitude by using a software called Phyphox on smart phones as an experimental tool, so as to explore the accuracy, harmony and the causes of its unique tones, and analyze the phenomenon of beat frequency during playing. The experiment is mainly divided into three parts: (1) Using Mason's law and the strike point theory, the vibration frequency of the string is qualitatively studied by changing the effective length of the string and the relative position of the strike point; (2) The Phyphox software on a smart phone is used to measure the vibration frequency of different strings and verify the existence of twelve equal temperament and overtone series; (3) The beat frequency phenomenon under different intervals and pitch combinations is measured. The experimental results show that there is an integer ratio relationship between the fundamental frequency and the double frequency of the piano, which accords with the theory of overtone series. The frequency ratio between adjacent sounds is close to the theoretical value, which verifies the twelve-average law. The phenomenon of beat frequency is observed in harmony, and the amplitude shows periodic changes. The experimental results support the application of Mason's law and twelve equal law in piano sound. In addition, the existence of beat frequency provides a theoretical basis for piano tuning. Future research could explore higher precision measurement devices and software to improve the automation of piano tuning and extend the study to other instruments.


    基于超导线圈的磁粒子成像磁场构建仿真研究
    FANLin1, TIAN Yushen2
    College Physics. 2025, 44(6):  7.  doi:10.16854/j.cnki.1000-0712.240341
    Abstract ( 132 )   PDF (329KB) ( 74 )  
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    Magnetic particle imaging (MPI) is a novel detection technology proposed in recent years, that achieves medical imaging by tracing the spatial distribution of the concentration of superparamagnetic iron oxide nanoparticles through a high-gradient magnetic field. Given the current lack of research on the application of superconducting coils in MPI, this paper demonstrates the feasibility of using high-temperature superconducting MgB2 coils to construct the gradient magnetic field in an MPI system through virtual simulation methods. Compared with traditional copper coils, MgB2 coils can significantly reduce the size and weight of the equipment while providing a finer scanning area and a higher magnetic gradient.

    On the origins of molecular force
    YANG Shijie
    College Physics. 2025, 44(6):  11.  doi:10.16854/j.cnki.1000-0712.240388
    Abstract ( 149 )   PDF (148KB) ( 115 )  
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    This paper employs the harmonic oscillator model to investigate the origins of inter-molecule potential. We find the interaction between non-polar molecules comes from the quantum effect, while the interaction between polar molecule includes both classical and quantum parts. The classical interaction is not the usual dipolar interaction: on the one hand, it decreases with the distance as 1R6; on the other hand, the interaction energy is proportional to the square of electric moment. Furthermore, the interaction exists even when one of the molecule has zero dipole moment. The appearance of this kind of potential is essentially due to the electric quadrupole moment.

    On calculation of the shape of the rotating earth
    College Physics. 2025, 44(6):  14.  doi:10.16854/j.cnki.1000-0712.240217
    Abstract ( 123 )   PDF (189KB) ( 86 )  
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    Based on the principle of coincidence between the surfaces of equal density and the surfaces of equal geopotential inside the rotating fluid Earth, a differential equations is established to determine the parameters of the surfaces of equal geopotential inside the Earth. Using internationally recognized Earth models, obtain theoretical values of the shape parameters of the rotating Earth through numerical solutions and compare them with actual values. Comparison shows that the solutions of the differential equations derived in this article are closer to the actual values than the solutions of existing related differential equations, and the differential equations in this article are more suitable as the basic equations for studying the shape of the Earth. Due to the complexity of the process of establishing differential equations, attempts are made to adapt the teaching approach and omit those cumbersome mathematical formulas. Emphasis is placed on introducing the physical concepts and solutions involved, as well as the key steps, key nodes, key formulas, and important results in mathematical derivation.

    analysis of the effect of water on the friction between objects
    College Physics. 2025, 44(6):  20.  doi:10.16854/j.cnki.1000-0712.240416
    Abstract ( 184 )   PDF (306KB) ( 102 )  
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    Taking the friction between the wooden block and the wooden desktop and the car tires and the ground as an example, the mechanism of the influence of the amount of water on the friction between the objects is analyzed. Analysis shows that the surface energy of water between the grooves in the wooden block will produce additional friction, the additional force and its corresponding friction force increase and then decrease with the increase in water volume; car driving in the presence of water film on the road surface, the impact of the water film reduces the pressure of the tires on the ground, thus reducing friction, the thicker the water film, the faster the driving speed, the smaller the friction between the tires and the ground.


    Discussion on the teaching of equilibrium stability of electrostatic #br# system in university physics#br#
    KANG Tian-rui, ZHANG Mei
    College Physics. 2025, 44(6):  26.  doi:10.16854/j.cnki.1000-0712.240559
    Abstract ( 141 )   PDF (395KB) ( 127 )  
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    By applying the condition for stability of equilibrium and Gausss law, it is proved that any point charge cannot be held in stable equilibrium by electrostatic forces alone; the scope of application is emphasized, and corresponding teaching suggestions are put forward. 

    A Fast Simulation Method for RHEED Patterns
    REN Quan, LI Yan-qing, ZHANG Xiao-qian, MIAO Lin
    College Physics. 2025, 44(6):  29.  doi:10.16854/j.cnki.1000-0712.240445
    Abstract ( 114 )   PDF (395KB) ( 37 )  
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    Reflection High Energy Electron Diffraction (RHEED) is extensively utilized for characterizing crystal structures. Compared to X-ray diffraction, RHEED offers the advantages of simplicity in operation and strong diffraction signals, holding great potential for applications in university physics and solid-state physics education. However, the lack of mature and intuitive simulation methods for RHEED patterns has hindered its broader adoption in educational settings. This article begins with the free-electron plane wave model to discuss the theoretical model of RHEED and extends it to the case of finite-sized crystals, providing detailed mathematical exposition. The results of this model fit well with relevant experiments, demonstrating its effectiveness and promoting the application of RHEED in related teaching fields.

    Convolution operations and some related applications
    ZHENG Shen-zhou, LI Yi-mei
    College Physics. 2025, 44(6):  34.  doi:10.16854/j.cnki.1000-0712.240495
    Abstract ( 149 )   PDF (199KB) ( 81 )  
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    In this paper, we introduce the basic concepts involving the convolution operators of discrete and continuous settings, review a few of algebraic and analytical properties of convolution, and give the geometric interpretation of convolution. The close relationship between convolution and Fourier transform is briefly recalled. As the applications of convolution operators, we study the mean value and smoothing, probability density function, central limit theorem, ordinary differential equation solution, and three kinds of typical partial differential equation by way of a combination of Fourier transform. Finally, the actions of convolution in general filtering and image processing are illustrated.

    The exploration of artificial intelligent method in physics teaching-nonlinear #br# layered topological structure in photonic neural network#br#
    LI Zhitong1, 2, YU Ke3, LI Yunheng3, ZHU Tianyu4, SHAN Sichao1, GU Yazhou1, YE Han1, 5
    College Physics. 2025, 44(6):  39.  doi:10.16854/j.cnki.1000-0712.240595
    Abstract ( 102 )   PDF (323KB) ( 77 )  
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    In order to motivate and inspire the research interests of undergraduate students and help them to learn more about the frontier research area, we provide an example on how to combine the photonic neural network into the frontier research field of physics, specifically the layered structure in topological photonics. The results can be used as an open project for the frontier research courses for physics major senior undergraduate student. It can help them to deeply understand the basic models in topological photonics and artificial intelligent modeling method such as neural network. This paper provides a road towards developing the fusion between research and teaching. 

    Can the effects of the weight on vertical vibration be ignored?
    CHEN Liqun1, 2, WEI Sha1, 2
    College Physics. 2025, 44(6):  44.  doi:10.16854/j.cnki.1000-0712.240328
    Abstract ( 114 )   PDF (253KB) ( 88 )  
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    The effects of the weight on vertical vibrations are analyzed. The Lagrangian equation is applied to a multi-degree-of-freedom time-independent conservative linear systems with the gravitational potential energy as a linear function of generalized coordinates to demonstrate that the weight can be canceled by the static deformation effect and then ignored together provided that the static equilibrium configuration is chosen as the origin the the generalized coordinates. A vertically vibrating one-degree-of-freedom nonlinear system is treated as an example to reveal that the weight changed both the linearized system and the nonlinear terms and thus cannot be ignored. The investigation outcomes clarify the validity conditions of relevant conclusions in domestical and international textbooks on vibrations.


    Discussion regarding the causes of cutoff voltage variation  in the teaching of photoelectric effect experiments
    ZHENG Xiao, LIU Fengning, ZHANG Guofeng
    College Physics. 2025, 44(6):  48.  doi:10.16854/j.cnki.1000-0712.240493
    Abstract ( 142 )   PDF (318KB) ( 101 )  
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    In the experimental teaching of the photoelectric effect, the Planck constant can be calculated by measuring the cutoff voltage at different frequencies, thus verifying the correctness of Einsteins equations and deepening the understanding of the quantum properties of light. Einsteins equation for the photoelectric effect shows that the cutoff voltage is a function of the frequency of the light and is independent of the intensity of the light. However, the change in cutoff voltage was found to be related to the light intensity, because the light intensity affects the number of photoelectrons emitted. However, once saturation is reached, the light intensity no longer affects the cutoff voltage. In addition, the existence of dark current will also affect the measurement of cutoff voltage, resulting in errors. Systematic analysis of these factors helps students to fully understand the photoelectric effect and its quantum properties.


    Analysis ofteaching cases from Bernoulli equation to altitude calculation
    YIN Hang1, SUN Jiangkai1, YE Long2, FENG Lin1, HAO Xiaotao1, GUO Liang3, LIU Jianqiang1, 3
    College Physics. 2025, 44(6):  53.  doi:10.16854/j.cnki.1000-0712.250109
    Abstract ( 88 )   PDF (104KB) ( 47 )  
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    Under the backdrop of building a strong education country, the demand for innovative talents is increasing day by day, and the cultivation of innovative talents has become an important reform goal and direction for higher education and teaching in Chinese universities. The key to cultivating innovative talents lies in optimizing students thinking patterns. Using a classroom teaching case from Bernoulli equation to altitude calculation, this article explores new ways to solve problems in college physics teaching through inspiring teaching methods and optimizing course design, promoting the formation of students independent thinking ability and enhancing their ability to solve problems independently, in order to better meet the demand for innovative talents in todays society.

    Teaching practice exploration of college physics for biotechnology majors
    CHEN Gaoyuan, CHEN Yongqiang, WU Xingzhi, GE Lijuan, LI Yajuan, MA Chunlan
    College Physics. 2025, 44(6):  56. 
    Abstract ( 86 )   PDF (335KB) ( 61 )  
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    This study focuses on the teaching practice of college physics in biotechnology majors. It begins with an analysis of several key issues identified by the authors team, including the disconnection between teaching content and students professional background, the rigidity and lack of diversity in teaching methods, and an inadequate assessment system. A series of improvement strategies are proposed, such as aligning course content more closely with students disciplinary needs, employing diversified instructional approaches, optimizing evaluation methods, enhancing teaching assessment and feedback mechanisms, and incorporating AI-assisted learning in college physics instruction. Through a two-academic-year comparative study involving biotechnology students, the results demonstrate that these measures effectively enhance students learning enthusiasm, mastery of knowledge, and problem-solving abilities, while also providing strong support for cultivating students innovative capabilities.

    Exploration and practice of seminar based college physics teaching with #br# the core of scientific research literacy cultivation——Taking “Throwing Motion” as an example#br#
    ZHANG Ying, WANG Hao, WEI Tong, YANG Xiong
    College Physics. 2025, 44(6):  63.  doi:10.16854/j.cnki.1000-0712.240467
    Abstract ( 98 )   PDF (855KB) ( 58 )  
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    Based on the national requirements for talent cultivation in universities, this article explores the research-oriented teaching centered on the cultivation of scientific research literacy, using college physics courses as the starting point. In response to the problems in traditional teaching models that emphasize concepts over innovation, transmission over practice, exam preparation over abilities, etc., which are not conducive to the cultivation of scientific research literacy, the teaching content is restructured and teaching methods are innovated to implement the goal of cultivating innovative talents′ scientific research literacy. Taking the throwing motion as an example, physics knowledge is case-based, starting from the classic allusion of “a hundred steps through a poplar tree”, questions are raised, and a progressive teaching method is adopted to guide students to engage in discussion based learning and shift from knowledge and skills to method literacy. After teaching practice, a questionnaire survey was conducted to investigate the recognition level of teaching modes and methods. It was found that students have a high degree of recognition, and their research awareness, methods, and spirit have all improved. This program has certain reference value for cultivating undergraduate research literacy.

    Practice and research of blended teaching based on optics course
    MA Hong, HOU Shuting, DUO Jiezhuoma
    College Physics. 2025, 44(6):  70.  doi:10.16854/j.cnki.1000-0712.240401
    Abstract ( 106 )  
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    In light of the unique geographical, cultural, and ethnic diversity characteristics of teacher education in the western region, as educators in western universities, we should deeply align with the core requirements of the national western development strategy at the undergraduate education stage, clearly establish the unique positioning of local discipline construction, and closely meet the urgent needs of regional teacher training. Based on the "Optics" course for normal majors in the western region, this article deeply analyzes the actual pain points and the rigidification of teaching models in current teaching, and proposes a series of teaching innovation strategies and improvement measures aimed at resolving these pain points. These strategies focus on the reshaping of teaching content and teaching process, the updating of course content and the expansion of scientific frontiers, and also emphasize the diversification of teaching methods, the enhancement of teacher-student interaction, and the improvement of the evaluation system. This article strives to play an active role in the construction of first-class physics majors for normal universities in the western region, aiming to cultivate physics education talents with both international vision and local sentiments, thereby contributing to the development of education in the western region.


    Exploration ofcollege physics teaching based on the analysis of test paper #br# and data download volume#br#
    XIAO Haibo, ZHU Jiakun
    College Physics. 2025, 44(6):  76.  doi:10.16854/j.cnki.1000-0712.240406
    Abstract ( 94 )   PDF (223KB) ( 43 )  
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    College physics, as a compulsory public foundation course for science and engineering students in higher education institutions, plays a significant role in cultivating students′ scientific thinking and subsequent professional courses learning. Based on the analysis of download statistic and final examination test paper scores, this paper effectively examines the gains and losses of students in understanding various course knowledge points. It identifies the issues existing in the teaching process and proposes corresponding strategies to optimize college physics instruction. The ultimate goal is to enhance the teaching effectiveness of college physics course.

    Discussion on the physical model in virtual simulation experiments#br#  for the measurement of sound velocity#br#
    YE Jinguo1, YANG Jing1, ZHU Qianyue1, WANG Zengxu2, LI Yongtao2, LI Bin2
    College Physics. 2025, 44(6):  81.  doi:10.16854/j.cnki.1000-0712. 240387
    Abstract ( 121 )  
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    Based on the experimental phenomena and measurement data of sound speed, a resonance frequency fitting model and a physical model of sound wave cone-shaped propagation attenuation formed by multiple reflections and superposition of sound waves at the source and receiver ends are proposed. According to the above models, the formulas for sound pressure amplitude and phase are derived, and a program is written and verified with actual measured data, obtaining the necessary parameters. The results show that the cone wave model is well consistent with the experimental data of both the resonance interference method and the phase comparison method, and the derived parameters provide theoretical guidance for the teaching of sound speed measurement and the construction of virtual simulation systems.


    Interaction energy of multiple uniformly magnetized and homogeneous permanent magnet spheres#br#
    ZHANG Xiao1, HUANG Fei2
    College Physics. 2025, 44(6):  86.  doi:10.16854 /j.cnki.1000-0712.240311
    Abstract ( 127 )   PDF (269KB) ( 66 )  
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    In this paper, a simple method for calculating the interaction energy of multiple uniform magnetized permanent magnet spheres is presented based on the magnetic charge view. Then, based on this method, we calculate and compare the relative stability of the line arrangement and ring arrangement of magnetic balls.
    Design and exploration of teaching experiments on optical diffraction of quasi-periodic structures#br#
    LI Dongkun, YAN Canhui, ZHAO Erli, LI Xiutai, WANG Ziyan, LIN Weihua
    College Physics. 2025, 44(6):  90.  doi:10.16854/j.cnki.1000-0712.240262
    Abstract ( 92 )   PDF (613KB) ( 64 )  
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    The Penrose tiling is a typical quasi-periodic pattern, and the diffraction of this structure has rich physical connotations. Based on the investigation of diffraction of Penrose tiling, this paper explores the possibility and feasibility of offering an experiment on diffraction of complex structures in Experiments of General Physics for physics majors, as well as University Physics Experiments for non-physics majors in science and engineering undergraduates. The teaching content of this experiment is preliminarily designed to learn to use computer programming to generate Penrose tiling, use spatial light modulators to load the graphics, build the diffraction setup by oneself, measure the experimental data, and analyse the complex structural graphics based on the diffraction patterns. This experiment breaks through the limitations of traditional periodic structures and guides students to explore the diffraction characteristics of quasi-periodic structures in depth. The experimental programme not only enriches the diffraction-related experimental contents of the general physics experimental courses, but also cultivates students' experimental design ability, hands-on ability and scientific literacy, which is of great significance in teaching and application.

    Acoustic wave control based onChladni plate
    ZHAO Mubai, ZHENG Liyang
    College Physics. 2025, 44(6):  97.  doi:10.16854/j.cnki.1000-0712.240497
    Abstract ( 88 )   PDF (297KB) ( 49 )  
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    This paper studies the propagation process of vibrations and the characteristic vibration patterns in Chladni plates, and gives a detailed discussion on the regulation and synthesis methods of Chladni patterns. Firstly, the mathematical model of thin plate vibration problem is established theoretically, successfully revealing the reasons for the appearance of vibration modes, and exploring the changes in vibration patterns caused by modal superposition. Furthermore, the Chladni patterns predicted by the theoretical model are verified by numerical simulation. Finally, by laying small particles on the plate surface, the experiment successfully observed different Chladni patterns. This study not only helps deepen understanding of the special characteristics of wave propagation in plates, but also provides control and synthesis methods for vibration patterns, providing ideas for vibration visualization research, particle manipulation and other applications.


    Teaching design and practice of university physics course from the #br# perspective of China’s aerospace—taking “Law of conservation of momentum” for an example#br# #br#
    XU Chunling, XIE Dong
    College Physics. 2025, 44(6):  102.  doi:10.16854/j.cnki.1000-0712.240296
    Abstract ( 120 )   PDF (303KB) ( 106 )  
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    College physics, as an important public basic course for engineering majors, not only provides necessary physical basic knowledge for the subsequent study of engineering majors, but also can analyze engineering design schemes for students and evaluate the feasibility of design schemes by scientific demonstration. Based on the perspective of aerospace engineering, this paper designs the teaching design and practice of college physics courses from a new perspective under the background of aerospace majors in our school, and integrates the curriculum thinking and politics “silently”. This paper takes the lesson “Law of conservation of momentum” as an example to explore and practice. Help students form physical thinking concepts and scientific literacy, learn to establish a general simplified model of rocket, use the law of conservation of momentum to approximate the speed expression of rocket, and analyze the advantages of threestage rocket on this basis. The whole teaching design process improves the students’ spirit of scientific inquiry and engineering design ability, and draws out a broader idea for the design of college physics teaching.


    Influence of double lens on the measurement of laser wavelength by Michelson interferometer#br#
    CAI Long-xian, YANG Lu-yang, LIU Guang-ju , YAO Guan-xin
    College Physics. 2025, 44(6):  108.  doi:10.16854/j.cnki.1000-0712.240429
    Abstract ( 103 )   PDF (198KB) ( 48 )  
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    In this paper, the application of double lens in Michelson interferometer experiment to measure laser wavelength and its influence on experimental results are discussed. By introducing a double lens system, we analyze the variation of spot size, ring pattern number and density, and discuss how to adjust the interference ring pattern by adjusting the lens distance. The experimental results show that the use of double lens system can significantly reduce the difficulty of Michelson interferometer adjustment, improve the experimental efficiency, and improve the accuracy of loop throughput counting.

    STEM education Idea——Design and manufacture of the gravity trolley#br#
    ZHAO Zonghong1, FEI Hongyang2, ZHANG Yifan2, PAN Mengmei2, LV Dongdong2
    College Physics. 2025, 44(6):  116.  doi:10.16854/j.cnki.1000-0712.240418
    Abstract ( 100 )   PDF (165KB) ( 50 )  
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    STEM is an educational concept that integrates multidisciplinary knowledge such as science, technology, engineering and mathematics, emphasizes interdisciplinary learning, and focuses on cultivating students′ innovative thinking and practical ability. Physics is an experiment-based discipline suitable for implementing STEM educational concepts. Under the guidance of STEM education concepts, we try to integrate science, technology, mathematics and engineering ideas into the design and production of the gravity car, improve the gravity car, and install a small generator in the car, which can not only demonstrate the conversion of gravity potential energy into kinetic energy, but also demonstrate the conversion of gravity potential energy into electrical energy. Through the exploration of interdisciplinary practical projects, students can understand the links between different disciplines from more perspectives.

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