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    26 February 2022 Volume 41 Issue 2
      
    The Climate System and Global Warming Reading of the 2021 Nobel Prize in Physics
    HU Yong⁃yun
    College Physics. 2022, 41(2):  1.  doi:10.16854 / j.cnki.1000-0712.210557
    Abstract ( 1012 )   PDF (977KB) ( 317 )  
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    The 2021 Nobel Prize in Physics is awarded to two climatologists and a theoretical physicist “for groundbreaking contributions to our understanding of complex physical systems”. Many of us would be surprised why two climatologists win the Nobel Prize in Physics. Here I present you my reading of the 2021 Nobel Prize in Physics, by addressing the following aspects: why is the climate system is called a complex physical system? The global greenhouse warming in the past century and possible future warming. The physical basis and brief history of global greenhouse warming. What are the contributions of the two climatologists, based on physical principles, to modeling of Earth climate, quantifying climate variability, reliably predicting global warming, and detecting and attributing global warming to anthropogenic activity.

    Hidden order in complex disordered systems ⎯An introduction to the 2021 Nobel Prize in Physics
    JIANG Shao⁃qin, YU Xue⁃jia, XU Li⁃mei
    College Physics. 2022, 41(2):  7.  doi:10.16854 / j.cnki.1000-0712.210633
    Abstract ( 971 )   PDF (1065KB) ( 344 )  
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    The Royal Swedish Academy of Sciences awarded half of the 2021 Nobel Prize in

    physics to Giorgio Parisi for the discovery of the interplay of disorder and fluctuations in

    physical systems from atomic to planetary scales. This article briefly reviews Parisi’ s

    contribution to the spin glass theory and stochastic processes.


    Savouring physics concepts
    AN Yu
    College Physics. 2022, 41(2):  15.  doi:10.16854/ j.cnki.1000-0712.210360
    Abstract ( 680 )   PDF (747KB) ( 278 )  
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    Some physics concepts need to analyze in details in order to understand deeply.This paper analyzes the interesting problems in physics teaching by taking Einstein diffusion coefficient, the longitudinal wave component of electromagnetic wave with photon rest mass and the minimum volume of state as examples.

    An intuitive derivation of one- and two-body operators in the second-quantization formalism
    WU Ning
    College Physics. 2022, 41(2):  18.  doi:10.16854 / j.cnki.1000- 0712.210221
    Abstract ( 1176 )   PDF (779KB) ( 647 )  
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    Second quantization is an important topic in postgraduate and senior undergraduate level Quantum Mechanics course. A key step in the development of the second-quantization formalism is the derivation of one- and two-body operators from the many-particle Hamiltonian and wave functions in the firstquantization language, which is usually difficult to understand for beginners. Taking the case of an assembly of identical fermions as an example, this paper provides a less ad hoc and intuitive derivation based only on the symmetrization postulate, the concept of “filling the vacuum” in the Fock space, and equivalence between the antisymmetrized many-particle wave function and the Fock state.

    The earth's surface deformation and fluctuation related to solid tide
    YU Feng⁃jun, JU Lin, TANG Zhen⁃jie, TIAN Jun⁃long
    College Physics. 2022, 41(2):  22.  doi:10.16854 / j.cnki.1000-0712.210121
    Abstract ( 645 )   PDF (798KB) ( 315 )  
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    Under the gravitational action of the moon and the sun, the earth's solid surface also has periodic fluctuations similar to the sea surface, this phenomenon is called solid tide. The cause of formation of solid tide is the same as that of sea tide, but its calculation is much complicated more than that of the latter. In this paper, the Kelvin earth model and a relatively simple method are used to calculate the earth's surface equation and fluctuation amplitude, and the related problems are discussed.


    Three kinds of methods for solving eigenvalues and eigenfunctions for the infinite square potential well
    LI Hai⁃feng, CHEN Kang⁃kang
    College Physics. 2022, 41(2):  26.  doi:10.16854 / j.cnki.1000-0712.210230
    Abstract ( 2606 )   PDF (818KB) ( 474 )  
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    Moving particle in the one-dimensional infinite square potential well is a quantum ideal model.In the traditional textbooks，the boundary condition of the potential well is particularly taken.Either it is symmetric about the coordinate origin point，or the left boundary value of the well is at the origin of the coordinate.First，it is presented how to solve the energy eigenvalues and eigenfunctions for this model with the arbitrary boundary condition by virtue of the three kinds of approaches.Moreover，the results obtained by the different methods are equivalent to each other.Then the derived results are discussed and analyzed.Furthermore，the general formulas for solving the energy eigenvalues and eigenstates for the one-dimensional infinite square potential well with a arbitrary boundary are acquired.It is easy to see that the two physical quantities are dependent on the well width，and the eigenfunctions are related to the boundary value.Finally，the one-dimensional results are extended to two and threedimensional infinite square potential wells with the arbitrary boundaries.

    Application of measurement uncertainty analysis in university physics experiments — gravity acceleration measured by single-swing
    ZHANG Zhu li, CHEN Xin lei, LU Mei hong
    College Physics. 2022, 41(2):  31.  doi:10.16854/j.cnki.1000-0712.200521
    Abstract ( 9741 )   PDF (826KB) ( 2476 )  
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    Gravity acceleration is an important mechanical constant in physics. There are many methods to measure the value of gravity acceleration, and the simple pendulum method is often used in university physics experiments. However, the experimental principle only studies the motion of the single pendulum ball and ignores the influence of the size of pendulum, buoyancy, cycloid mass and other factors, so the measurement results are not accurate enough. The relative accurate formula of gravity acceleration and the corresponding synthetic standard uncertainty formula are obtained by correcting the system error that caused in the measurement of gravity acceleration by the simple pendulum method. Finally, the measured data are analyzed and calculated reasonably, and the more accurate experimental results are obtained.
    A brief introduction of the experimental course of quantum key distribution for undergraduate students
    SUN Shi⁃hai
    College Physics. 2022, 41(2):  38.  doi:10.16854 /j.cnki.1000-0712.210208
    Abstract ( 830 )   PDF (951KB) ( 217 )  
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    Due to its special advantages，quantum information technology has attracted more attentions，and is considered as the trend of information technology.Thus，the training of students and engineers with a background in quantum mechanics is considered as a strategic task for future talent reserves.However，due to the abstraction，intersectionality，cuttingedge and complexity，the experimental course is difficult for undergraduate students.In this paper，the course，quantum key distribution，in Sun Yatsen University is introduced and it is hoped to be of some help to the teaching and training of quantum information technology.

    Application of Hall sensors in electromagnetic induction experiment
    SUN Xiao⁃yan, WU Tian⁃hao, HUANG Qing, TIAN Yong⁃ning, LI Cheng⁃jin
    College Physics. 2022, 41(2):  44.  doi:10.16854 / j.cnki.1000-0712.210314
    Abstract ( 711 )   PDF (900KB) ( 995 )  
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    It is a typical experiment of electromagnetic induction that a magnet falls in a nonferromagnetic metal tube.In this paper，the dynamics for the magnet is set up and solved according to simplification model.A set of drop velocity of the magnet are measured by a system consisted of Hall sensors，LED and STM32.The result is analyzed and compared with the theoretic simulation values.

    Modeling and simulation of magnetoresistive electromagnetic launch
    ZHANG Jing⁃zhuo, YAO Lu⁃feng, YANG Shao⁃hua
    College Physics. 2022, 41(2):  49.  doi:10.16854 / j.cnki.1000- 0712.210180
    Abstract ( 650 )   PDF (900KB) ( 180 )  
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    In this paper，the mechanism of the reluctance launcher is analyzed，and the equivalent effect of the launching process is obtained.The theory model of the reluctance launcher is built by using the magnetic moment model.The dynamic equations of projectile are derived by combining the circuit model，then the main factor influencing of the projectile fired is analyzed，and MATLAB simulation results are given.
    A pplication of BOPPPS model in college physics
    LV Wen⁃ming, LI Xiao⁃duan
    College Physics. 2022, 41(2):  53.  doi:10.16854 / j.cnki.1000-0712.210164
    Abstract ( 820 )   PDF (857KB) ( 474 )  
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    There exists some shortcoming in traditional college physics teaching.In this paper BOPPPS model was applied to college physics with taking Doppler Effect as an example to design micro-class. In this teaching framework, learning initiative of students changed from passive acceptance to active inquiry. BOPPPS model effectively attracted students’ interest and improved learning efficiency. Furthermore, students could deeply understand and master abstract physical concepts, and apply relevant theoretical knowledge to engineering practice. It was a good reference for improving teaching and learning quality.

    Diagnosis of plasma emission spectrum and measurement of N2 vibration temperature
    YANG Shi⁃zhe, CHEN Han⁃lin, FENG Xin, LIU Chen⁃yu, TAO Xiao⁃ping, WANG Zhong⁃ping, ZHANG Zeng⁃ming
    College Physics. 2022, 41(2):  58.  doi:10.16854 / j.cnki.1000-0712.210213
    Abstract ( 710 )   PDF (841KB) ( 197 )  
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    Vacuum with pressure of several pascals is generated by a selfmade cylindrical tube. The emission spectra along the central axis of the tube of 65Pa air plasma and 14Pa air-CO2 plasma are observed, the strongest of which are recognized as the first and second positive system of N2. The vibration temperatures along the central axis are calculated using the relative intensity of the second positive system of N2.
    Measurement of the relationship between light intensity and photocurrent in photoelectric effect based on self-made “ black box” experimental device
    YANG Ying, ZHANG Wen⁃pan, ZHANG Ji⁃cai
    College Physics. 2022, 41(2):  63.  doi:10.16854 / j.cnki.1000-0712.210099
    Abstract ( 1169 )   PDF (792KB) ( 257 )  
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    Based on the self-made “black box” experimental device, this paper verified the relationship between saturated photocurrent and light intensity by three methods: The first method is to study the volt-ampere characteristic curve under different light intensity by controlling the voltage of the phototube; The second one is to study the photoelectric characteristic curve of photocell by changing the distance between phototube and light source under the same light intensity; And the third one is that the relationship between photocurrent and light intensity can be directly measured by using light intensity sensor. The experimental data were collected and analyzed by PASCO platform in real time. When the saturation was not reached, the experimental results show that the photocurrent increased with the increase of light intensity.

    Three dimensional multi particle suspension and control device based on transducer array
    XU Yu⁃qi, XU Hui⁃jie, GUO Rui⁃xue, FANG Ming⁃yue, ZHENG Jian⁃bin, XIE Cui⁃ting
    College Physics. 2022, 41(2):  67.  doi:10.16854 / j.cnki.1000-0712.210216
    Abstract ( 604 )   PDF (873KB) ( 306 )  
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    Aiming at the problem of small number of suspended particles and limited levitation space in the current three-dimensional acoustic operation technology, a design scheme of acoustic levitation device composed of three pairs of opposed transducer arrays is proposed. By changing the phase difference of the transducer array, the three-dimensional manipulation of particles is successfully realized. This device can be used to measure the speed of sound with a relative error generally about 2%~5%, and the measurement should carry out under a relatively strict environment.
    Flow around a cylinder at high Reynolds #br# numbers—a case study of candle burning
    LUO Yun, WANG Xiaoning, ZHAO Xuyang, MENG Dezhong, HAO Huiying
    College Physics. 2022, 41(2):  71.  doi:10.16854 / j.cnki.1000-0712.210138
    Abstract ( 740 )   PDF (835KB) ( 705 )  
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    In view of high Reynolds number flow around a cylinder, the problem of how to put off a fire is carried out based on experimental research. It is showed that within a certain range, the flame extinction time is proportion to the obstacle diameter, the distance between candles and obstacles and the candles burning rate, and it is inversely proportional to the flow velocity of the obstacle. Through the analysis, it is found that the experimental data and the theoretical analysis are consistent, which indicate that the experiment conclusion is correct and the experimental method is feasible. Furthermore, it provides an important support for the indepth study of the flow around a cylinder, flame combustion problems and the relationship between them.
    Research and application of optical properties of rotating liquid surface
    LIU Tian⁃qi , FENG Yi⁃chen , ZHANG Meng⁃yue , LI An
    College Physics. 2022, 41(2):  77.  doi:10.16854 / j.cnki.1000-0712.210038
    Abstract ( 755 )   PDF (781KB) ( 1564 )  
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    While the cylindrical container is rotating around the central axis, the liquid contained in it is driven to rotate around the same axis at the same time. At a relatively stable state that the rotational speed of the liquid is nearly constant, a paraboloid can be formed on the surface of the liquid due to the combined action of gravity and the centrifugal force. Since the optical focal distance of the paraboloid is only related to the local acceleration of gravity and the rotate speed of the container, this equipment can be used to measure the g of the local place. What is more, the optical focal ability enables it to be used as the main reflector of a simple Newtonian-Focal-System telescope. And the lateral magnification of this telescope is also a property that can be measured.

    The further discussion on the dynamics of pulley
    WANG Guo⁃ping , FENG Li⁃li , MU Cheng⁃fu , LI Bai⁃qing
    College Physics. 2022, 41(2):  82.  doi:10.16854 / j.cnki.1000-0712.210167
    Abstract ( 789 )   PDF (771KB) ( 677 )  
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    In Atwood’s machine, when both pulley and string have mass, the theoretical expressions of tension on both sides of the string and of acceleration of weight objects are derived using momentum theorem. The acceleration a(t) changing with time and the relationship between velocity v and moving distance h under different string weights are discussed.

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