College Physics

Classical physics: the integration of theoretical mechanics and electrodynamics

QIN Sixue

College Physics. 2026, 45(1): 1. doi:10.16854/j.cnki.1000-0712.250502

Abstract ( 221 )

PDF (742KB) ( 178 )

Related Articles | Metrics

The traditional physics teaching system of the so-called “four core mechanics” emphasizes “disassembly” over “integration”. In particular, theoretical mechanics and electrodynamics have long been virtually disconnected and underrepresented. On the one hand, theoretical mechanics focuses on the laws of motion and mechanical principles, lacking a discussion of the nature of forces, whereas electrodynamics precisely reveals the nature of forces through the language of fields. On the other hand, electrodynamics focuses on the experimental laws and equations of motion of electromagnetic fields, lacking a discussion of the nature of electromagnetic fields, whereas theoretical mechanics precisely reveals the nature of electromagnetic fields from the perspective of fundamental degrees of freedom. Drawing on these two perspectives, we attempt to establish a “classical physics” system that integrates theoretical mechanics and electrodynamics: course foundations, Lagrangian mechanics, Hamiltonian mechanics, applications of classical mechanics, correspondences between forces and fields, laws of electromagnetic fields, static electromagnetic fields, dynamical electromagnetic fields, and an introduction to relativity. Instead of the solution of specific mechanical and electromagnetic problems, this system emphasizes the profound principles, beautiful structures, and extensive connections of classical physics.

AC Hall effect measurement using a lock-in amplifier

YUE Guantong, SUN Shijia, Li Qiang, Chen Dong, CAO Derang

College Physics. 2026, 45(1): 6. doi:10.16854/j.cnki.1000-0712.250270

Abstract ( 147 )

PDF (888KB) ( 41 )

Related Articles | Metrics

This paper presents a high-precision Hall effect measurement system utilizing a lock-in amplifier and outlines its performance optimization. The systems measurement accuracy is validated using standard Hall effect samples, with a comparative analysis of results from DC and AC testing methods. Three standard samples are selected for the experiments. In the DC measurement, the fitting errors of the measured Hall sensitivity range from approximately 0.45% to 1.0%. For the AC measurement, the influence of frequency and current on the measurement results is investigated by varying the frequency and voltage parameters of the lock-in amplifier. The results show that, in the low-frequency range, the Hall sensitivity fitting error in the AC measurement is as low as 018%. Experimental findings demonstrate that the AC Hall effect measurement method provides superior noise resistance and sensitivity compared to the DC method, enabling more stable and accurate detection of weak signals. This study offers a systematic reference for optimizing Hall effect measurement technology and highlights the potential of the AC method for high-precision signal detection.

Dual optical path compensation enhanced U-shaped sensor based on evanescent wave total internal reflection for liquid concentration measurement

LIU Dongjie, MO Dongxiao, CAO Ding, WANG Sunjun, LIU Xiang, HE Zhuoran

College Physics. 2026, 45(1): 13. doi:10.16854/j.cnki.1000-0712.250190

Abstract ( 139 )

PDF (914KB) ( 29 )

Related Articles | Metrics

A U-shaped acrylic device is designed based on the principle of total reflection, and a method of liquid concentration detection based on dual optical path is proposed. By designing a U-shaped acrylic device and utilizing the evanescent wave total internal reflection effect at the liquid-acrylic interface, this study establishes a quantitative relationship between transmitted-light-intensity attenuation and the refractive index of opaque liquids. Real-time comparison between the experimental and control groups effectively eliminates the system error caused by the semiconductor lasers output-power fluctuations. The experimental results show that the absolute error of the methods measurements is less than 2%, the relative error is maintained at approximately 5%, and the coefficient of determination (R2) of the established concentration-relative-refractive-index calibration curve is 0.9967. Notably, the device achieves accuracy comparable to that of traditional methods used for transparent liquids, even when detecting opaque liquids. The system has the advantages of simple operation, an easily understandable principle, and low cost, providing a low-cost solution for the detection of liquid concentration in physics laboratories.

The general solution analysis of sectorial cylindrical resonant cavities and waveguides

SUNQi, MAZiyin, MEIZhonglei

College Physics. 2026, 45(1): 19. doi:10.16854/j.cnki.1000-0712.250187

Abstract ( 108 )

PDF (851KB) ( 32 )

Related Articles | Metrics

This paper presents a detailed study on the solution of the Helmholtz equation for sectorial cylindrical resonators and waveguides. By employing the method of separation of variables, we systematically analyze the resonance and propagation modes of electromagnetic waves within such resonators and waveguides. The electromagnetic field distributions under various boundary conditions are thoroughly investigated. The correctness and practicality of the analysis are verified through theoretical derivations and numerical simulations. This study provides a theoretical foundation for the design and fabrication of sectorial cylindrical resonators and waveguides.

The potential of magnetic moment in a static external magnetic field

LI Zhibing

College Physics. 2026, 45(1): 23. doi:10.16854/j.cnki.1000-0712.250096

Abstract ( 126 )

PDF (821KB) ( 60 )

Related Articles | Metrics

A static external magnetic field exerts a force on magnetic moment which is equal to negative gradient of the potential, that is the definition of the potential in electrodynamics. However, the physical meaning of the potential is not given by this definition. We will discuss the physical content of the potential, showing that the potential of a macroscopic magnetic moment and magnetic field-depending energy of an atom are different in physics, although they have the same expression. The one for the atom is part of the internal energy of the atom.

application of univariate cubic equations in solving physics problems

WU Shouchong1, XIAO Fei2

College Physics. 2026, 45(1): 25. doi:10.16854/j.cnki.1000-0712.250139

Abstract ( 118 )

PDF (1034KB) ( 69 )

Related Articles | Metrics

This article illustrates the application of cubic equations in solving problems related to kinematics, dynamics, gravitational fields, electrostatic fields, and electromagnetic fields through five presented examples. These examples include mock exam questions from various provinces and cities as well as real exam questions from the college entrance examination. Using techniques such as rational root theorem and reasonable approximation, examples are given of how cubic equations can be factorized. Finally, the characteristics of high school physics problems involving cubic equations in analysis and solution are discussed, and examples are provided for reference on how to combine generative artificial intelligence software to empower test question design and teaching expansion.

Design and development of optical fiber teaching experiment based on the OBE concept: Distributed measurement of optical fiber loss as an example

DANG Yunli, ZHAO Zhiyong, ZHAO Can

College Physics. 2026, 45(1): 30. doi:10.16854/j.cnki.1000-0712.250115

Abstract ( 103 )

PDF (1237KB) ( 33 )

Related Articles | Metrics

This article is based on the educational philosophy of OBE (outcome-based education), breaking away from the traditional teacher-led scheme and student-execution of experimental steps in teaching methods. It proposes a new experimental teaching approach, i.e. the students design the experimental schemes independently, while the teachers provide approval, feedback, and follow-up, so as to explore the student-led teacher-responsible experimental teaching model. Typically, taking the measurement of optical fiber loss as the theme and following the "device—system" knowledge map, it combines existing discrete verification experimental projects, designing and developing exploratory experiments for distributed optical fiber loss measurement that is in line with cutting-edge technology. This enhances students′ ability to apply multiple knowledge points comprehensively, improves students′ independent inquiry and innovation capabilities, and forms an experimental teaching philosophy of "autonomy in scheme, systematization in process, diversity in results, and comprehensiveness in grading, further improving the quality of innovative talent training.

Research on virtual simulation experiment of Newton ring apparatus based on LabVIEW

ZHENG Wenli, ZHAO Xiaoman, LI Yincang, SUN Yuhang, WANG Wenlu, LIU Zhe

College Physics. 2026, 45(1): 37. doi:10.16854/j.cnki.1000-0712.250216

Abstract ( 124 )

PDF (1176KB) ( 37 )

Related Articles | Metrics

This paper develops a virtual simulation platform for Newtons rings interference experiment using LabVIEW software. The platform enables simulation of real Newtons rings interference experiments, allowing users to adjust parameters and visualize simulation results in real-time. Measurement experiments for liquid refractive index are conducted separately on both the real Newtons rings apparatus and the virtual simulation platform. A comparative analysis of the experimental results verify the accuracy of the virtual simulation platform. Additionally, the platform is employed to simulate and investigate the impact of changes in medium refractive index (N), incident light wavelength (λ), and curvature radius (R) on the characteristics of Newtons rings interference fringes, specifically analyzing fringe distribution patterns and light intensity features under different conditions. In theoretical and experimental teaching related to Newtons rings interference, this platform can directly be used for teaching demonstrations, effectively integrating theory with experiment and significantly enhancing teaching effectiveness.

Development and teaching application of the equipment forelectrical properties of semiconductors

LUO Yu-bo, LUO Aladansunbuer

College Physics. 2026, 45(1): 44. doi:10.16854/j.cnki.1000-0712. 240574

Abstract ( 118 )

PDF (1082KB) ( 24 )

Related Articles | Metrics

Since the Hall coefficient, Seebeck coefficient, and resistivity of semiconductor materials cannot be tested on the same device and sample, we integrate the Vanderberg method for Hall coefficient and resistivity testing with the quasi-steady-state method for Seebeck coefficient testing, successfully designe an experimental equipment for Hall coefficient, Seebeck coefficient, and resistance measurement of semiconductor materials in the temperature range of room temperature to 573 K. Then, two typical semiconductor materials, including N-type InSb and P-type MnTe, are measured using this equipment as experimental teaching content. This experimental teaching effectively improves the understanding and application of solid state physics’ knowledge of students, thus achieving the organic combination of theoretical teaching and experimental teaching.

Measuring the electrical conductivity and magnetic permeability of materials by using low-frequency RLC circuits

CHEN Zhen, JIANG Yu-ting, HU Biao, YANG Xiao-zhou, YAO Zhen-yu, CHEN Ting

College Physics. 2026, 45(1): 54. doi:10.16854 /j.cnki.1000-0712.240592.240592

Abstract ( 118 )

PDF (1127KB) ( 34 )

Related Articles | Metrics

The measurement of the electrical conductivity and magnetic permeability of materials has important applications in engineering. In this paper, a long straight cylindrical rod is placed inside the inductor coil of a low-frequency RLC circuit. By analyzing the power of the circuit and the power consumed by the magnetization of the conductor rod, the relationship between the change in the impedance of the inductor coil before and after insertion and the magnetic permeability and electrical conductivity is obtained. After accurately measuring the inductance voltage with a lock-in amplifier, the electrical conductivity and magnetic permeability of the cylindrical rod are calculated using this relationship. Through verification with multiple materials, the correctness of this calculation model is proved, providing a new idea for the rapid measurement of the electromagnetic properties of materials.

Intelligentmeasurement experimental device of gravity acceleration based on drop ball method and its application#br#

CHEN Jing, YANG Xiao-hua, ZHU Qiao-ping

College Physics. 2026, 45(1): 54. doi:10.16854/j.cnki.1000-0712. 240576

Abstract ( 92 )

PDF (1178KB) ( 29 )

Related Articles | Metrics

Aiming at the deficiencies of traditional gravitational acceleration measurement experimental devices, this study has developed a high-precision automated measurement device based on the falling-ball method for experimental teaching. The device employs high-precision Hall sensors and an ESP32 microcontroller to process analog signals through algorithmic methods. After multiple rounds of instrument optimization and algorithm debugging, the device is capable of accurately determining the gravitational acceleration. Experimental results show that compared with the reference value of gravitational acceleration in Yinchuan, the measurement error of the system is less than 2.5%. The device effectively reduces experimental errors and overcomes the visual errors and operator reaction time biases introduced by the use of stopwatches, photoelectric gates, or dot timers in traditional experiments. It is of great significance in stimulating students' interest in learning physics experiments.

Exploration of practical Paths for college physics experiment teaching in the context of digital transformation：a qualitative study based on typical cases

GUO Shuqing, ZHAO Gaiqing

College Physics. 2026, 45(1): 58. doi:10.16854/j.cnki.1000-0712. 250027

Abstract ( 127 )

PDF (1263KB) ( 41 )

Related Articles | Metrics

With the rapid development of information technology, digital transformation has become a significant trend in the reform of university physics experiment teaching. This paper starts by addressing the limitations of traditional experimental teaching models and analyzes the advantages of digital technologies in improving data acquisition efficiency, enhancing the accuracy of phenomenon visualization, enabling resource sharing, and promoting teaching flexibility. The paper further explores the practical applications of digital transformation in the teaching of university physics experiments at our institution. Through the introduction of intelligent experimental equipment, implementation of hierarchical and personalized experiment designs, integration of competitions with research training, and adoption of diversified teaching methods, significant improvements have been achieved in the efficiency and quality of physics experiment teaching. These measures have also effectively stimulated students’ interest in learning and enhanced their innovation capabilities.

Equivalence method in two-body spring systems：fostering scientific thinking

JIANG Jing, BAO Xiaojun, LIU Ziran

College Physics. 2026, 45(1): 63. doi:10.16854/j.cnki.1000-0712.250173

Abstract ( 110 )

PDF (1157KB) ( 52 )

Related Articles | Metrics

This work innovatively proposes the reduced stiffness coefficient method for the two-body problem involving spring interactions. By establishing equivalent parameters (reduced stiffness coefficients), this method simplifies the processing of multi-body systems and clarifies the presentation of physical processes. In terms of student competency development, the approach leverages transformation training from “complex systems” to “equivalent single bodies,” aiding students in mastering analogical thinking and problem reconstruction skills. Additionally, through formula derivation, it inspires students to grasp the thinking paradigms in scientific research and reinforces the educational value of the equivalence concept.

Suitability and quality testing of a conceptual assessment tool for university physics thermodynamics - an empirical analysis based on Rasch modeling

TANG Li1, FANG Wei2, 3, XIAO Yue4

College Physics. 2026, 45(1): 67. doi:10.16854/j.cnki.1000-0712.250134

Abstract ( 110 )

PDF (1407KB) ( 22 )

Related Articles | Metrics

Based on the Rasch model, this paper conducted a quality test on four thermal concept scales (TCE, HTCE, TCS, and STPFaSL) with 573 college students as participants in order to assess their measurement properties and applicability in different cultural contexts. The results of the study show that the overall quality of the four scales is relatively good, which can properly reflect the level of students’ understanding of the relevant thermal concepts, but the difficulty of very few questions does not fully cover the ability level of all participants, and needs to be optimized. The average scores of domestic participants were generally higher than those of foreign participants, but the trend of scores of domestic and foreign students on the four scales remained consistent, indicating that they have some commonalities in their understanding of thermal concepts.

Reform and practice of college physics teaching based on blended learning model combining online and offline instruction

XIANG Hui, REN Xian-pei, PAN Bao-cai, YUAN Yu-quan

College Physics. 2026, 45(1): 74. doi:10.16854/j.cnki.1000-0712.250152

Abstract ( 133 )

PDF (1218KB) ( 83 )

Related Articles | Metrics

Under the transformation of talent cultivation models in local applied undergraduate institutions, college physics courses exist numerous problems, including the disconnection between teaching content and majors, outdated teaching methods, singular evaluation systems, uneven student foundations, and so on. Taking Sichuan University of Science ＆ Engineering as an example, based on the standards of professional certification, a “one-line-five-elements” college physics curriculum system, which integrates basic theory, course-based ideological and political education, physics frontiers, practical teaching, and subject and major, has been constructed. By adopting “Internet + Education”, a blended teaching platform that combines online and offline instruction has been established, and differentiated teaching has been implemented. The reforms in college physics have made beneficial attempts in enhancing teaching quality for teachers and learning capabilities for students, which provide references for similar universities to carry out blended teaching in college physics.

Historical evolution of quantum mechanical theoretical frameworks

WU Youshen

College Physics. 2026, 45(1): 80. doi:10.16854/j.cnki.1000-0712. 250177

Abstract ( 102 )

PDF (1294KB) ( 54 )

Related Articles | Metrics

Quantum mechanics, a cornerstone of modern physics, has undergone significant theoretical development since its emergence in the early 20th century. This paper classifies quantum mechanical frameworks into three categories—core formalisms, physical interpretations, and extended tools—and examines 14 key frameworks, spanning from matrix mechanics (1925) to Bayesian quantum mechanics (21st century). Each framework is analyzed in historical context, elucidating its theoretical foundations, mathematical formulations, and practical applications,with analogies to clarify complex concepts. The study traces the evolution of quantum mechanics from singleparticle to manybody systems and from concrete computations to abstract algebraic structures, highlighting its profound influence on mathematics, philosophy, and quantum information science.

The rigidity problem in rotating reference frames and dynamic analysis of particles

DAI Qiyu, FANG Xiongjun

College Physics. 2026, 45(1): 86. doi:10.16854/j.cnki.1000-0712.250411

Abstract ( 198 )

PDF (1293KB) ( 69 )

Related Articles | Metrics

This paper investigates the rigidity of rotating reference frames and discusses the motion of particles within such frames. Starting from Born’s relativistic rigidity condition, it is proven that the prerequisite for Einstein’s rotating disk to satisfy the rigidity condition is that the disk undergoes uniform rotation. Within a uniformly rotating reference frame, the geodesic equations of particles are analyzed, revealing the existence of forbidden regions related to constants of motion in the particle trajectories. For nonuniformly rotating reference frames, particle geodesics under different rotation functions are analyzed by defining an energy constant. The equations of motion for particles in both uniformly and nonuniformly rotating frames are analyzed, establishing the relationship between accelerations measured in the rotating frame and the laboratory rest frame. It is found that this relationship corresponds to the classical mechanical counterpart under the lowvelocity approximation. The discussions in this paper can further deepen the understanding of issues concerning the rigidity of rotating frames and the motion of particles within them.

Thermal effects onsurface tension: a modular optimization approach in pull-off measurement system

XU Zhengyu, CHEN Xin, YANG Chen, XING Rui, WANG Shuzhuo, LIU Xiang, PENG Xiaoniu

College Physics. 2026, 45(1): 92. doi:10.16854/j.cnki.1000-0712.250165

Abstract ( 75 )

PDF (1298KB) ( 22 )

Related Articles | Metrics

This study addresses the problem of significant errors in measuring liquid surface tension coefficients using the traditional pull-off method. The improved apparatus retains the pull-off methods advantages—such as simple operation and a straightforward structure—and innovatively incorporates a horizontal adjustment module, a peristaltic pump system, and a thermostatic water bath. Experimental results show that the improved device enhances measurement precision by reducing the relative error to 0.5%. This advancement provides a more accurate and reliable approach for measuring liquid surface tension coefficients in general physics experimental teaching, which is crucial for improving the quality of experimental education.

The analysis and verification of halfwave loss of ultrasound longitudinal waves at different medium interfaces

ZHANG Mujing, WANG Yaping, YANG Haolin, WANG Sihe, TENG Yongping, HAN Jingyu

College Physics. 2026, 45(1): 96. doi:10.16854/j.cnki.1000-0712.250170

Abstract ( 79 )

PDF (1364KB) ( 17 )

Related Articles | Metrics

This paper derives the amplitude relationship between the incident and reflected waves of ultrasonic longitudinal waves at the interface of different media based on the wave equation. The amplitude is related to the acoustic impedance of the two media and the incident angle. Using COMSOL, an ultrasonic longitudinal wave detection model is established to perform finite element simulations of the longitudinal wave propagation characteristics at the interface, and experiments are designed for verification. In the case of no grazing incidence, when an ultrasonic longitudinal wave is incident from a high-impedance (dense) medium to a low-impedance (sparse) medium, An abrupt phase shift of π occurs at the interface relative to the incident wave, resulting in a half-wave loss phenomenon. Conversely, when the interface is between two media with similar impedances, the reflected wave and the incident wave are in phase with no half-wave loss. This paper discusses the half-wave loss phenomenon of ultrasonic longitudinal waves at different media interfaces from theoretical, simulation, and experimental perspectives, providing significant theoretical support and experimental evidence for the application of ultrasonic longitudinal waves in non-destructive testing. It also offers a valuable supplement to relevant textbooks and teaching cases in industrial applications.

Improvement of experimental device for measuring liquid surface #br# tension coefficient by pull-off method#br#

LI Chao-ran, ZHANG Hong-xia, XU Rui, CHENG Zhi-hai, LIU Juan-juan

College Physics. 2026, 45(1): 101. doi:10.16854 /j.cnki.1000-0712.250257

Abstract ( 103 )

PDF (1397KB) ( 30 )

Related Articles | Metrics

The measurement of liquid surface tension is a fundamental experiment for physics undergraduates. However, due to the large systematic error, increasing the experimental accuracy and precision has always been a persistent challenge in this project. We propose an improvement to the device by incorporating micrometer lifting platform and spiral height regulator based on the pull-off method. These modification enable a better control over the liquid membrane as well as a measurement of its height during detachment which is a critical parameter for evaluating the operational stability. In addition, the liquid membrane gravity was considered and its influence on experimental results is investigated quantitatively by applying metal rings with identical mean diameters but different wall thickness, thereby the accuracy of liquid surface tension coefficient measurements has been enhanced effectively.

The temperature compensation optimization for steady-state method thermal conductivity measurement experiments

XING Chengliang1, SONG Fei2, ZHANG Liuwan2

College Physics. 2026, 45(1): 105. doi:10.16854/j.cnki.1000-0712.250251

Abstract ( 86 )

PDF (1371KB) ( 20 )

Related Articles | Metrics

We measure the radial and axial temperature gradients in a steady-state thermal conductivity experiment. After calibration, the axial gradient is determined to be -0.221°C/cm, while the radial gradient measures -0.0045°C/cm. Under the assumption of linear temperature distribution, the temperature difference between the upper and lower surfaces of the test sample at thermal equilibrium is reconstructed. Additionally, the time-dependent heat dissipation rate of the cooling disk is quantified. The results demonstrate that the thermal conductivity of the sample is 0.157 W/(m·K), representing a 6.0% improvement in measurement accuracy compared to conventional methods.

Application of a γ stirling engine in a gravity energy storage system

ZHANG Yimeng1, GUO Yan1, DING Jiahao1, MA Junhao1, WANG Yi1, WENG Yuyan1, 2, FANG Liang1

College Physics. 2026, 45(1): 111. doi:10.16854/j.cnki.1000-0712.250221

Abstract ( 79 )

PDF (1435KB) ( 19 )

Related Articles | Metrics

This experiment designs and investigates the application of a γ Stirling engine in gravity energy storage. The displacer of a dual-cylinder γ Stirling engine is optimized to integrate a regenerative function, effectively improving heat exchange efficiency. By connecting a gas pressure transducer and a high-speed camera, real-time pressure and volume changes during engine operation are captured, and instantaneous p-V diagrams are plotted. Experimental results indicate that under a temperature difference of 178 K, the Stirling engine achieves a rotational speed of 126 rpm, a mechanical output power of 0.6 W, and a conversion efficiency of 0.17%. Although the efficiency is relatively low, it highlights the coupling of a Stirling engine with gravity energy storage, offering substantial educational value for demonstrating thermodynamic principles and providing a novel approach to addressing challenges in renewable energy grid integration.

Determination of lens refractive indices in achromatic objectives

Li Song-mian1, 2, SONG Fei1, LIU Ying-ying1, ZHANG Liu-wan1

College Physics. 2026, 45(1): 117. doi:10.16854/j.cnki.1000-0712.250258

Abstract ( 87 )

PDF (1312KB) ( 18 )

Related Articles | Metrics

This study focuses on the optical system of achromatic objectives for refracting telescopes. The focal length of a convex lens is measured using the parallel light method, and its refractive index is determined via the thick lens formula. By measuring the focal length of a compound lens composed of convex and concave lenses, the focal length of the concave lens is deduced, enabling the determination of its refractive index. Based on the achromatic condition formula, the lens materials and Abbe numbers are derived, validating the design principles of achromatic compound lenses.

Table of Content