College Physics

Rotational symmetry and orbital angular momentum in the field of a magnetic monopole

LIN Qionggui

College Physics. 2020, 39(10): 1-4. doi:10.16854 / j.cnki.10000712.200156

Abstract ( 1010 )

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A generalized analysis of rotational symmetry in quantum mechanics is presented for a charged particle moving in the field of a magnetic monopole. The generalized orbital angular momentum is obtained，which is the same as that obtained previously by a different method. The transformation of the wave function under rotation contains an extra phase factor compared with the ordinary case without the magnetic monopole field. The explicit expression for this phase factor is worked out. The familiar quantization condition for electric charge is obtained by requiring the phase factor to be ±1 under a rotation of angle 2π.

Calculating and drawing the mutual inductance coefficient and the force between two coaxial circular currents

ZHOU Qunyi, MO Yunfei, HOU Zhaoyang, ZHOU Lili

College Physics. 2020, 39(10): 5-11. doi:10.16854 / j.cnki.10000712.190468

Abstract ( 1105 )

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The mutual inductance coefficient between two coaxial circular currents is visualized by means of dimensionless method proposed here. The relationships of the mutual inductance coefficient with the radius and distance between the two circular currents are displayed according to these graphs. Moreover，the method of calculating the axial and radial forces between the two coaxial circular currents is discussed. The two forces are visualized by means of dimensionless method. The relationships of force with the radius and distance between two circular currents are shown.

On chemical potential of phonons in Einstein solid model

HOU Jixuan

College Physics. 2020, 39(10): 12-13. doi:10.16854 / j.cnki.10000712.190449

Abstract ( 1086 )

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Thermodynamic quantities of the Einstein solid model are studied via the microcanonical approach.We point out that the number of phonos in Einstein solid model cannot be defined independently and thus the chemical potential of phonos cannot be defined in the microcanonical ensemble. The chemical potential of phonos can be calculated only if the number of phonons can fluctuate. And we prove that the chemical potential of phonos in Einstein solid model strictly equals to zero in other ensembles.

Kinematic equation of satellite and its isochronous point by point trajectory

SHAO Yun

College Physics. 2020, 39(10): 14-17. doi:10.16854 / j.cnki.10000712.200039

Abstract ( 1838 )

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According to the elliptic orbit equation and angular momentum conservation formula of satellite in polar coordinate system，the kinematic equation in the form of implicit function of the satellite is obtained by integration，and the isochronous point by point trajectory diagram，the change curve diagrams of polar coordinates r and θ with time t of the satellite with eccentricity e = 0.6 are made. It is pointed out that r changes most rapidly with t at the intersection of the elliptical orbit and the right rectum，that is，the radial velocity of the satellite is the largest.The kinematic equation obtained in this paper is actually another expression of Kepler’s equation，but its reasoning process is easier to understand. The detailed integration process and relevant conclusions given in this paper may provide reference for the teaching and learning of relevant contents.

A simple and practical approximate formula for the period of simple pendulum

YANG Tianhu, YUE Zhiming, LI Yuhong,

College Physics. 2020, 39(10): 18-21. doi:10.16854 / j.cnki.10000712.200071

Abstract ( 1179 )

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Through the analysis and derivation of the power series of the accurate solution of the simple pendulum period，a simple，convenient and practical approximate formula of the simple pendulum period is given，and the relative error is less than 0.05% in the range of amplitude nearly 180°.

Discussion on the solution of electric field strengths distribution on the axis of a uniformly charged hemispheroid

WU Xianyun, LI Bin

College Physics. 2020, 39(10): 22-28. doi:10.16854 / j.cnki.1000 0712.200033

Abstract ( 2038 )

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For uniformly charged hemispheroid，the distribution of the electric field strength on its axis cannot be calculated by the Gauss law because the charge distribution is not highly geometrical symmetry. Based on the superposition principle of electric field strength and the method of electric potential gradient，the analytical solutions of electric field strengths distribution on its axis is derived strictly，the results show that the analytical solutions of the electric field strengths distribution in each region of the axis of the uniformly charged hemispheroid are different，the same conclusions are obtained by various methods. For the charged body with uniform and symmetrical distribution，it is easier to select the appropriate charge element and use the superposition principle of field strength to solve the field strength distribution，while the potential gradient can be used to solve the non-uniform and symmetrical distribution when it is difficult to solve by the superposition principle.

The extension of the concept of entropy ———from thermal entropy to information entropy

LI Jun, WANG Zhicheng, WU Yuxuan, YUAN Zhi,

College Physics. 2020, 39(10): 29-33. doi:10.16854 / j.cnki.1000 0712.200059

Abstract ( 1129 )

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This paper first introduces the establishment process of the concepts of thermodynamic entropy and information entropy. Based on the application example of entropy in information theory，the correlation between thermodynamic entropy and information entropy is found. Finally，the relationship between information and energy， information entropy and thermodynamic entropy is discussed through Maxwell’s demon solved by Szilard，Landauer and modern experiments.

Digital holography experiment design with the off-axis angle supervised accurately

XU Xianfeng, MA Tianyu, XU Liang, SUN Yuting, JIAO Zhiyong

College Physics. 2020, 39(10): 34-37. doi:10.16854 / j.cnki.1000 0712.190567

Abstract ( 748 )

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Digital holography experiment with the off-axis angle supervised accurately is designed to satisfy the requirement of off-axis angle. After introducing one reflector，two beam splitters，supervisin g CCD and calculating the off-axis angle by spatial spectrum analysis，the angle between the reference and the objective beams is supervised online. This setup can not only realize the alternation between the in-axis state and off-axis state without rearrangement，but also can separate the original objective image from the direct term and the twin image when the recorded digital holography is used for reconstruction. It can decrease the demanding of digital holography recording on CCD and make the reconstructing view field used effectively. Resolution target is used as the objects in the experiments carried out. The feasibility and effectiveness of this off-axis angle supervising setup are verified by optical experiments.

Some problems in the experiment of Fourier series decomposition based on RLC resonance circuit

LIU Weihui, DAI Kun, LI Hongliang, MA Ruixiang, MIAO Yongping

College Physics. 2020, 39(10): 38-41. doi:1016854 / jcnki10000712.200076

Abstract ( 793 )

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The values of resistance，capacitance and inductance are the key factors of the amplitude ratio and

waveform quality in the Fourier series decomposition experiment. Several experiments based on the three factors are

carried out in this paper. The results have shown that suitable value range of the resistance and strategy of dynamical adjusting of the capacitance is contributed to get good wave form quality and small deviation of amplitude ratio.

In addition，the experiment on inductance has verified that the greater its value is，the better the waveform is. In

conclusion，the above experiments can supply valuable reference to the experiment of Fourier series decomposition.

Discussion and improvement of the experiment for measuring the optical rotation of solution based on light intensity

College Physics. 2020, 39(10): 42-47. doi:10.16854 / j.cnki.1000 0712.190552

Abstract ( 932 )

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The rotation angle of light polarization direction is calculated by using the change in light intensity

after the light passes through the optically active solution，thereby calculating the optical rotation rate of the solution. We analyze the influence of various factors on the results in the experiment，and give the improved method and correct the final calculation formula. The data is measured by experiments to verify the correctness of the theory.

The translation and evolution of "Uncertainty Relation" in China

HOU Jiali, SUN Yongping, ZHAO Fengqi,

College Physics. 2020, 39(10): 48-53. doi:10.16854 / j.cnki.1000 0712.200068

Abstract ( 1037 )

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" Uncertainty Relation" was first translated as " 测不准原理" in China. Based on the literature research and conceptual analysis，the translation and introduction process in China is clarified in this paper. And meanwhile the reasonable analyses of possible causes have been made in terms of the translation，which contributes to comprehending the development of the terminology more clearly. The work represents the progress of Chinese scientists' understanding of research on Heisenberg's outstanding scientific achievements with the aim of further enhancing the recognition of the term " uncertainty relationship" in quantum mechanics.

Shelter Island Conference and postwar American Physics mature

ZHANG Yan, YANG Qingyu

College Physics. 2020, 39(10): 54-59. doi:10.16854 / j.cnki.1000 0712.200110

Abstract ( 763 )

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The Shelter Island Conference is a famous conference in the history of science. The main topics are the divergence of quantum mechanics and the infinity of electromagnetic energy. The lamb experiment shows that the dilemma of quantum field theory is not an infinite quantity，but a finite and small quantity. The task of theoretical physicists is to prove that the quantity does exist. The renormalization scheme adopted by Betty and Feynman

and the Hamiltonian regular transformation method used by Schwinger make these difficulties solved. The new generation of physicists in the United States almost independently completed the creation of quantum electrodynamics. The success of this conference made the maturity of American Physics after the war.

Reconsideration of the mathematic model and numerical simulation of swing with parametric self-excited oscillation

YANG Baiyu, WANG Cuixiang, WANG Binke, LI Chunwang, FAN Qi, TIAN Changhui

College Physics. 2020, 39(10): 60-63. doi:10.16854 / j.cnki.1000 0712.200095

Abstract ( 763 )

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The swing is regarded as a variable length simple pendulum. Based on Gauss function，the velocity

of pendulum ball relative to pendulum rod is designed. When the swing moves with a large angle，it can meet the

requirements of “squatting down on the highest point and standing up on the lowest point”，because its parameters

are independent of swing motion. On this basis，the dynamic differential equation of swing is established，and the

motion of swing is simulated numerically，the motion process，work and energy transformation mechanism of swing

are obtained.

Analysis of the angle of grenade throwing in battlefield environment

LIU Xie-quan, LU Hai-peng, WANG Yu-ru

College Physics. 2020, 39(10): 64-66. doi:10.16854 /j.cnki.1000-0712.190571

Abstract ( 1772 )

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It is a common way of individual combat to destroy enemies by throwing grenades. By simulating the battlefield environment，the best shot angle when throwing a grenade across a house，a high wall，or in a mountain environment is analyzed，which has certain significance for students' training and combat.

Design ofgeneral course with history of optics

OU Yang-min, WANG Jin-dong

College Physics. 2020, 39(10): 67-71. doi:10.16854 /j.cnki.1000-0 2. 0062

Abstract ( 1100 )

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As a representative of scientific education，generaleducation of science contributes to the improvement of the scientific literacy of people. The general courses，Developments of Optics and Human Civilization，focus on the history of opticsas the main body of the course and sets three levels of progressive teaching contents in practice. They correspond to the basic and remedial，the advanced and integrated，the extensive and diversifiedteaching contents. First，this curriculum designconstructs the system of basic opticalknowledge. Then it guides students to analyze the development regularity and the scientific thinking in the scientific research. Moreover，it realizes the dialogue between optics and human history as well as society throughthe multidisciplinary，cross-cultural perspective. It is the goal of the course construction to achieve the popularization for the wholesubject of optics to students.

Teaching design of telescope in the course of principles of optics

SHEN Chang-yu, LI Chen-xia, SHEN Wei-min

College Physics. 2020, 39(10): 72-75. doi:10.16854 /j.cnki.1000-0712.200031

Abstract ( 1261 )

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Classroom teaching is the main place not only for training students，but also to practice the curriculum

politics and to satisfy the concept of engineering education accreditation which emphasize the student centered

and achievement oriented education. Based on the teaching content of telescope in the course of principle of optics

which is the core for the optoelectronic information science and engineering，a guiding teaching design integrating

with the ideology and politics is developed，the process of the teaching design and the implementation are expounded

in detail in order to cultivate students' habits of thinking before，during and after school. It is hoped to give

some suggestion to the classroom teaching which is student centered and focused on the application of knowledge.

Construction of medical physics course by using multiple teaching reforms

LIU Feng-qin, GAI Zhi-gang, YU Shu-yun, LIU Jian-qiang

College Physics. 2020, 39(10): 76-80. doi:10.16854 /j.cnki.1000-0712.200024

Abstract ( 986 )

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The construction of medical physics course at Shandong University is introduced in this paper. Many teaching reforms are taken in medical physics in recent years. Student-centered teaching philosophy runs throng the teaching process. Medical physics teaching resources are put on MOOC platform and opened to everyone. New form textbook is studied and will be published，in which a perfect teaching textbook system is established. In addition， the blended teaching mode based on SPOC online course is used and flipped class mode is tried in the face-to-face class. Furthermore，a variety of effective teaching methods are employed in classes. Research results have showed that the multi-dimensional teaching reforms have greatly promoted the level of medical physics course construction and improved the quality and effect of teaching at the same time.

Universal formula for the expansion of the commutation relation of multioperators multiplication

WANG Qian-xing, LI Peng,

College Physics. 2020, 39(10): 81. doi:10.16854 /j.cnki.1000-0712.200106

Abstract ( 1556 )

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The expansion results of the commutation relation of multi-operators multiplication are studied，and a universal expansion formula is found. The formula can be proved strictly，and the proof process is also shown. The formula can directly show the expansion result of the commutation relation for multi-operators multiplication. The formula is used to expand the commutation relation of some common quantum mechanics operators. The expanded results using the formula are the same as that obtained through the normal procedure. These results further confirm the correctness of the formula.

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