College Physics

Finite element analysis of microarea temperature distribution in micronanostructured thermoelectric devices

CAO Hongzi1, MI Yimin1, DU Yanchen1, WANG Fangkun1, QIN Feng1, 2, HUANG Junwei1, 2, YUAN Hongtao1, 2

College Physics. 2025, 44(5): 1. doi:10.16854/j.cnki.1000-0712.240381

Abstract ( 247 )

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The thermoelectric effect in two-dimensional materials is one of the cutting-edge research directions in condensed matter physics, and the magnitude of the micro-area thermal field gradient in two-dimensional thermoelectric devices plays a decisive role in the strength of the thermoelectric signal. This article uses COMSOL simulation software and uses a grid partitioning method that combines quadrilateral grid and swept grid, and simulates the thermal field distribution in two-dimensional thermoelectric devices. By comparing the simulation results of thermal field distribution under different heating wire shapes, lengths, thicknesses, widths, and heating currents, etc., it is found that the temperature gradient generated by rectangular heating wires is the most significant, which reveals the law that the temperature gradient decays with the distance from the heating wire as an inverse proportional function, and solves the technical problem of how to obtain a large temperature gradient on the sample in the thermoelectric effect detection experiment of two-dimensional materials. This article will not only provide strong guidance for the design and preparation of micro-nano structures such as heating wires in two-dimensional thermoelectric devices, but also has important significance for improving thermoelectric conversion efficiency and solving the heat dissipation problem of highly-integrated mictro-nano devices.

Study on the magnetic field generated by a uniformly charged spherical shell rotating at a constant speed

ZHU Mengzheng, ZHAO Chunran

College Physics. 2025, 44(5): 11. doi:10.16854/j.cnki.1000-0712.240452

Abstract ( 320 )

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This paper uses the basic knowledge of electromagnetic field theory to study the magnetic field distribution of a uniformly charged spherical shell rotating at a constant speed in the whole space. First, due to the symmetry of the current distribution, the corresponding magnetic field is axially symmetric; the two components of the magnetic induction intensity at a certain point are directly written according to the BiotSavart law, and numerical simulation is performed to calculate the magnetic field inside and outside the spherical shell. The results show that the inside of the spherical shell is a uniform magnetic field. Secondly, the magnetic field is discussed respectively using the magnetic scalar potential and the magnetic multipole method. By comparing the magnetic field outside the spherical shell, it is found that the current distribution in this problem has certain particularities. Finally, the magnetic field excited by a spherical shell formed by a single thin wire with a steady current passing through it is discussed.

Experimental study on the correction of output performance for solar cells

CHEN Zewen1, TIAN Haixing1, YANG Qian2, NAN Chenhui1, MAO Shengchun1, LU Gang2, WANG He1

College Physics. 2025, 44(5): 15. doi:10.16854/j.cnki.1000-0712.240238

Abstract ( 172 )

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Studying the difference between the actual output performance and rated output performance for solar cells is not only the key of understanding electrical performance of solar cells, but also the basis of evaluating performance of solar modules in the field. In this paper, the principle of the correction of output performance for photovoltaic cells is discussed. The special experiment setup for testing solar cells performance is built. Then, the current-voltage(I-V) curves of the solar cell under different conditions are measured. The correction coefficients of I-V curves are determined by the theoretical equations and experimental results. The measured I-V curves are corrected to the standard test condition and compared with the rated I-V curve. Finally, the correction errors and the source of errors are analyzed. The relative errors of these corrected parameters are less than 1%, which can meet the requirements of the undergraduate experimental teaching.

Measurement of Youngs modulus of metal wires by using Phyphox software

QI Jingqiang, LIU Menglin

College Physics. 2025, 44(5): 15. doi:10.16854/j.cnki.1000-0712. 240325

Abstract ( 213 )

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In the experiment of measuring the Youngs modulus of metal wire using the optical lever method, it is necessary to calculate the small angle of rotation of the optical lever system by measuring the distance from the optical lever axis to the scale and the change in the scale reading. In this paper, a sensor for measuring the slope angle in the mobile phones Phyphox software is used to directly measure the small angle of rotation of the phone, thereby obtaining the small elongation of the metal wire. The relative error of measuring the Youngs modulus of the metal wire using this method is only 0.5%. Through wireless networks, mobile phones and computers can be interconnected, and experimental data can be displayed in real-time in the form of charts on the computer desktop, making the experimental process more intuitive.

MATLAB visualization assisted teaching of forced vibration experiment

LIU Tian-gui1, CHEN He2, ZHOU Qun-yi1, ZHOU Yan-ming1, QIN Zhi-hui1

College Physics. 2025, 44(5): 26. doi:10.16854 /j.cnki.1000-0712.240471

Abstract ( 194 )

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Based on the forced vibration experiment principle, the effect of the forced vibration initial phase on experimental measurement results is discussed. MATLAB is used to visualize the analytical solutions and amplitude-frequency characteristics under different resistance torques for forced vibration. Taking students as the center and problem oriented, students are guided to analyze the physical mechanism of the operation process during the explanation of experiment principle by means of MATLAB visualization, which can strengthen the experimental inquiry ability of student. Some achievement about the teaching reform has been achieved in teaching practice.

Exploration of introducing precision measurement into optics and optoelectronics experimental teaching#br#

ZHENG Jihui, XUE Chenpeng, SUN Xiaoyun, DING Songfeng, ZHANG Zuxing

College Physics. 2025, 44(5): 33. doi:10.16854/j.cnki.1000-0712.240212

Abstract ( 167 )

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Optics and optoelectronics experiments course serve as practical applications of classical theories in the fields of physical optics and optoelectronics, aiming to familiarize students with the principles and applications of relevant devices within optoelectronics. In order to delve into the educational significance of related research outcomes, this paper integrates research and teaching, mutually enhancing each other. We introduce frequency-modulated laser measurement techniques into the laboratory course. Building upon the foundation of conventional fixed-frequency electro-optic modulation experiments, we design experiments to delve deeper into electro-optic modulators and laser interference phenomena. By observing signals from photodetectors, we provide students with intuitive demonstrations of precision measurement processes and calculate distance information of measured targets based on principles.

Bridging basic and advanced physics: digital teaching innovations in Methods of Mathematical Physics

ZHANG Shuqing

College Physics. 2025, 44(5): 37. doi:10.16854/j.cnki.1000-0712.240417

Abstract ( 171 )

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As a pivotal course in the physics curriculum, “Methods of Mathematical Physics” serves as an essential bridge, directly influencing students' understanding and application of advanced physical concepts. Given the courses highly abstract and complex content, the integration of digital technologies has become an imperative approach to enhancing teaching quality and stimulating student interest. This paper delves into how digital technology can be utilized to strengthen the connection between mathematical methods and other physics courses. By presenting specific examples such as the application of complex numbers in wave problems, the intuitive demonstration of Fourier transforms in signal analysis, and the application of spherical functions in quantum mechanics, the paper demonstrates that digital technology not only simplifies the comprehension of mathematical concepts within the course but also significantly enhances students ability to flexibly apply these concepts in solving physical problems. Overall, the introduction of digital technology not only facilitates the integration and linkage of different course contents, enriches teaching methods, but also inspires students practical interest and innovative thinking, thereby paving new paths for enhancing the teaching effectiveness of the Methods of Mathematical Physics course.

Construction andpractice of artificial intelligence course of university physics based on knowledge map

ZHANG Hongguang1, LI Yongtao1, YANG ZhiHong1, CHEN Wei1, BI Lan1, DONG Huiyuan1, WANG Yunhui1, SHAN Junhao2

College Physics. 2025, 44(5): 41. doi:10.16854/j.cnki.1000-0712.240396

Abstract ( 296 )

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Currently, artificial intelligence (AI) is profoundly changing education. The University Physics team of our university has innovatively launched a knowledge mapdriven AI course on the Wisdom Tree platform, and constructed a new teaching mode of ‘teacher/student/machine’ interaction. This paper outlines the design concept of the teachermachinestudent collaborative teaching system, the construction, implementation, effectiveness and reflection of the AI course. From the practical effect, the learner image based on knowledge graph and adaptive learning provide students with personalized learning can effectively improve independent learning and learning performance, which provides an experience reference for the construction of AI courses in basic science and engineering courses.

An analysis and interpretation of the basic physical principles of#br# “A suggestion on the detection of the Neutrino”#br#

WEN Shuying1, NING Changchun1, SUN Zheng2, FENG Youliang1

College Physics. 2025, 44(5): 48. doi:10.16854/j.cnki.1000-0712.240614

Abstract ( 147 )

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This paper delves into Wang Kan-changs 1942 publication in Physical Review， “A suggestion on the detection of the Neutrino” offering a detailed explanation of the historical background， physical concepts， and principles involved at the level of undergraduate physics. It proceeds to outline the five significant experiments conducted between 1942 and 1952 that utilized Wang Kan-changs proposal， the K-capture method， for neutrino detection. Special emphasis is placed on examining the technical reasons behind the success of Daviss 1952 experiment.

Fourball exploring — secrets hidden behind a question of high school physics competition#br#

CHEN Yifan1, YANG Huan2

College Physics. 2025, 44(5): 58. doi:10.16854/j.cnki.1000-0712.240228

Abstract ( 237 )

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Currently, in the undergraduate teaching process, particularly in the field of physics, the emphasis is mainly on presenting “perfect” scientific principles and solvable exercises. However, it is precisely those unsolvable problems that can reflect students’ understanding of the entire issue and stimulate their creativity. This paper provides an indepth analysis of a rigid body problem in the 39th National Physics Competition for high school students (alternate paper) and combines it with numerical calculations. It is found that when the initial angular speed of ball D is very small, the result given by the original reference answer is reasonable. In addition, the oscillating phenomenon of ball A’s angular velocity as the increasement of initial speed of ball D is studied. According to the analysis of fixed points, the critical initial speed at which linear evolution to damped oscillation is estimated. Some peculiar phenomena that occur during the evolution are also studied, and it is pointed out that the transition from sliding friction to static friction provides a dynamical correspondence to the occurrence of stable state.

A new method to eliminate the Gibbs paradox in statistical physics

Wei Yuxin1, Xu Bo2, Liu Quanhui2

College Physics. 2025, 44(5): 65. doi:10.16854/j.cnki.1000-0712.250153

Abstract ( 339 )

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The Gibbs paradox in statistical physics refers to the fact that the entropy of a classical ideal gas given by Boltzmann statistics is not extensive, which is inconsistent with experimental results. The conventional solution is that particles are inherently quantum, and indistinguishable. Therefore, the paradox can be resolved by introducing an indistinguishability factor. This paper provides a new calculation method that automatically gives the correct expression of the entropy of an ideal gas, the core of which is to resort to the particle number representation. This method has obvious advantages: there is no need to resort to quantum statistics, nor to the integral function of the entropy formula in thermodynamics or other artificial corrective methods, etc.

Design of celestial motion simulation based on Python

WANG Yichen1, WANGXinyi1, LiYing1, LIUYuying2, LIChunyan2, ZHAO Zhichao2, WANG Wenjie2

College Physics. 2025, 44(5): 68. doi:10.16854/j.cnki.1000-0712.240295

Abstract ( 205 )

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Celestial motion is a core research area in astrophysics. Utilizing fundamental laws and formulas from classical mechanics, such as the law of universal gravitation and the momentum theorem, we design and develop a celestial motion simulation system. This is achieved using advanced programming language Python, along with visualization libraries Mayavi, Matplotlib, and Vhmap. Through this system, we vividly simulate orbital transfer problems and the dynamic behaviors of binary and triple star systems, providing an intuitive representation of celestial motion trajectories.

Solution and visualization of forced vibration of a circular membrane #br# with fixed boundary#br#

HE Zhuo-yan, GUO Qin

College Physics. 2025, 44(5): 76. doi:10.16854/j.cnki.1000-0712.240139

Abstract ( 180 )

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This paper takes circular membranes as the research object, and uses the separation of variables method and impulse theorem method to separately study their free vibration and forced vibration problems. The free vibration and forced vibration solutions in the form of Bessel functions are obtained, and the results are visualized and analyzed. Research has found that when a circular membrane vibrates freely, for the same order, the higher the resonant circular frequency, the more wrinkles it will have; The higher the order, the more the number of nodal diameters, and the more diverse the fold morphology. When a circular membrane is forced to vibrate, due to the set external force being independent of the angle, under the conditions of fixed boundaries, no initial displacement, and no initial velocity, the forced vibration solution of the circular membrane that satisfies the initial conditions is also independent of the angle, resulting in a centrally axisymmetric distribution of the vibration shape. At the same circular frequency and different times, the number of folds is basically the same. As time changes, the central wave packet oscillates up and down around the central axis. At the same time, as the circular frequency changes, the vibration pattern of the circular membrane also changes. At the same circle frequency and at the same time, as the root value of the Bessel function in the external force increases, the number of folds in the circular membrane vibration increases.

Applications of regularization and renormalization theories #br# in problems related to the Dirac function potential #br#

JIANG Chao, REN Xi-jun

College Physics. 2025, 44(5): 82. doi:10.16854/j.cnki.1000-0712.240097

Abstract ( 143 )

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This paper introduces regularization methods and the concept of renormalization by analyzing the bound and scattering states of the two-dimensional Dirac delta function potential. First, it discusses the difficulties in solving the bound states of the Dirac delta function potential. Then, it establishes the relationship between the bound state energy values and theoretical coupling parameters through regularization. Next, based on this relationship, it analyzes the scattering cross-section of the potential and demonstrates its independence from the regularization process. Finally, a brief conclusion is provided.

Development and application of real-time non-contact temperature measurement device

JIANG Jin1, ZhANG Jinming1, TAN Jiamin2, YANG Yubo1, ZHANG Wenkai1

College Physics. 2025, 44(5): 86. doi:10.16854/j.cnki.1000-0712.240211

Abstract ( 138 )

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Utilizing the basic principles of a Michelson interferometer, a temperature measurement device can be designed. This involves placing a transparent sample in one arm of the Michelson interferometer and allowing a laser beam to pass through it. Interference fringes become apparent when the beams from the two arms interfere. Since these fringes are affected by the optical path difference between the two arms, a sensor is used to record changes in the interference fringes. By analyzing these changes in the optical path difference using a microcontroller, variations in the samples refractive index, and consequently its temperature, can be calculated. Based on this principle, we propose the development of a real-time non-contact temperature measurement device equipped with an interference fringe automatic recognition system. This system intelligently identifies the number and direction of fringe movements to achieve temperature measurement. We will conduct tests to assess the accuracy of measurements and discuss potential applications of this device in other fields such as photothermal effects, measuring expansion coefficients, and elastic moduli.

Digitalization empowers the teaching of physics experiments: #br# the application exploration of Tracker software#br#

CHENG Lixian, LI Mingyang, WANG Jia, YANG Zijiang

College Physics. 2025, 44(5): 92. doi:10.16854/j.cnki.1000-0712.240270

Abstract ( 213 )

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Tracker is an opensource software for video analysis and modeling. Inducting reasonably Tracker in physics experiment teaching to optimization design can not only enhance the digital construction of experimental courses, but also stimulate students’ interest in exploring experiments. In this paper, the application of Tracker software in distance measurement, trajectory tracking, and angle measurement in physical experiments is explored by combining three experiments: laser wavelength measurement by Young’s doubleslit interferometry, gravitational acceleration measurement by single pendulum and the influence of pendulum angle θ of simple pendulum on measurement results of gravitational acceleration. The experimental results show that the Tracker software can improve the measurement accuracy of the adjacent bright fringe spacing Δx in the Young’s doubleslit interference experiment, and more accurately measure the period of the single pendulum in the gravitational acceleration measurement experiment of single pendulum, and also has good measurement results for exploring the influence of the pendulum angle θ on the measurement results in the experiment of single pendulum measurement of gravity acceleration experiment. Therefore, the introduction of the experiment can effectively reduce the parallax caused by human eye observation and the measurement error in the experiment, and can accurately measure the angle and other physical quantities that are difficult to accurately measure in the actual scene.

Description of Lagrangianfield theory for perfect fluids

College Physics. 2025, 44(5): 99. doi:10.16854/j.cnki.1000-0712.240426

Abstract ( 170 )

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Xing ZiZheng1, He XiaoKai2, CAO ZhouJian1
(1. School of Physics and Astronomy,Beijing Normal University, Beijing 100875, China;
2. School of Mathematics and Statistics, Hunan First Normal University, Changsha, Hunan 410205, China)

Abstract:Lagrange theory is an important teaching content in theoretical mechanics and celestial mechanics. The perfect fluid, as a paradigm of field theory, is also an important teaching content in theoretical mechanics, celestial mechanics, and field theory. But interestingly, there are few textbooks that explain fluid mechanics from the perspective of Lagrangian theory. This article combines thermodynamics, generalized coordinate transformation, and differomorphism together to analyze the Lagrangian theory of perfect fluids. A mathematical theorem which provides a restriction condition for the generalized coordinates of Lagrange theory is specifically discussed. This theorem demonstrates the non-existence of a Lagrangian theory for a perfect fluid with only three field quantities including particle number density, fluid energy density, and four velocity field as generalized coordinates. The content of this article can not only help readers deepen their understanding on thermodynamics in fluid mechanics, differomorphism transformation in general relativity, generalized coordinate transformation in Lagrangian theory, and Lagrangian theory description of fluids, but also help readers further understand Lagrangian theory itself. The contents

Introduction and Solutions to the Problem 3 of Theoretical Part of the 54th International Physics Olympiad

JIANG Shuo, Xubo Guo, AN Yu, ZHANG Liubao, RUAN Dong

College Physics. 2025, 44(5): 105. doi:10.16854/j.cnki.1000-0712.240468

Abstract ( 384 )

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This paper discusses the theoretical problem 3 of the 54th International Physics Olympiad (IPhO). The title of the problem is called Black Widow Pulsar. At glance it appears similar to the APho (Asia Physics Olympiad) 2024 theoretical problem 3, however the essence is a typical mechanics problem about the accretion of binary star system and the equilibrium of a single gas star. The question is composed of two parts, first is concerned with the transfer of mass (accretion) in a binary star system; the second is the equilibrium of a single gaseous star, under the influence of gas pressure and gravity. It utilizes classical models in mechanics and decent in difficulty and quite suitable for high school Olympiad students. This is common feature for this 54th IPhO. A detailed description and answer to this problem is given here.

Systematic error analysis of an experimental device for verifying the #br# conservation of momentum in the text book of the Peoples Education Press#br#

LI Mei1, WANG Feng2, JIANG Bing3, SHAO Yun4

College Physics. 2025, 44(5): 112. doi:10.16854/j.cnki.1000-0712.240322

Abstract ( 294 )

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The article focuses on the experimental setup for momentum conservation during the collision of two small balls at the end of an inclined groove in the latest version of the Peoples Education Press Selective Compulsory One textbook. It is divided into two cases: when the incident small iron ball contacts or does not contact the bottom of the track groove, and derives the relative increase in the velocity of the small iron ball exiting the horizontal groove after rolling and sliding motion after colliding with a small stationary glass ball at the groove end (relative to the ideal case without friction), as well as the system relative error for this momentum conservation experiment. Theoretical calculation results indicate that the values of both are generally large, with larger values observed when the incident small iron ball is not in contact with the bottom of the track groove. The experimental error results for the incident small iron ball not contacting the bottom of the track groove are roughly consistent with the corresponding theoretical error results, both of which show that there is indeed a significant systematic error in this experimental device in the latest version of the textbook. It is recommended to replace it with a complete collision experimental device available on the market, which has been tested to have a relative error of only ±2%.

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