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Table of Content

    20 August 2018 Volume 37 Issue 8
      
    Three classes of inequivalent squeeze operators
    LIN Qiong-gui
    College Physics. 2018, 37(8):  1-3.  doi:10.16854 /j.cnki.1000-0712.170649
    Abstract ( 1270 )   PDF (153KB) ( 428 )  
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    The squeeze operators of three classes are presented. The ideal squeezed states with arbitrary degree of squeezing can be obtained by acting any one of them on coherent states. The familiar squeezed operator is a special case of the three classes. The three classes are not equivalent to one another,namely,they cannot be transformed into one another by linear canonical transformations
    Investigation on the mode density of lattice vibration
    WANG Qing-qing,GONG Hao,CHENG Rong-long,GE Li-xin
    College Physics. 2018, 37(8):  4-7.  doi:10.16854 /j.cnki.1000-0712.170620
    Abstract ( 3287 )   PDF (237KB) ( 1338 )  
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    The mode density of the lattice vibration (phonon density of states),i.e.,the mode number in the unit frequency interval,is a physical quantity reflecting the density of the phonon in the space of the wave vector. In order to calculate accurately the lattice heat capacity varying with temperature,one must calculate the density of lattice vibration by using more accurate method,and then grasp the thermodynamic properties of materials. Some general textbooks on the part of the explanation are obscure and difficult. This paper starts from the physical meaning of the lattice vibration,analysis and derivation of 1D,2D and 3D different systems of lattice vibration mode density formula,then the lattice heat capacity formula of Debye model for different systems is presented.
    The Roche’s limit of fluid guest aster
    YU Feng-jun
    College Physics. 2018, 37(8):  8-12.  doi:10.16854 /j.cnki.1000-0712. 170625
    Abstract ( 2825 )   PDF (597KB) ( 1093 )  
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    In the middle of the nineteenth century,the French astronomer Roche reported the Roche’s limit of fluid companion star. Fluid guest aster refers to a fluid object passing through a main star with large mass. If the distance between the fluid guest aster and its main star satisfies certain conditions,it should be torn by the tidal force of the main star. This condition is derived by using the principle of minimum potential energy.
    The exact solution and COMSOL simulation of temperature inside a finite length energized cylinder
    CUI Xin-tu,FANG Yi-zhong,SHEN Han,HUANG Zhen-cheng,LIAO De-ju,FENG Rao-hui
    College Physics. 2018, 37(8):  13-18.  doi:10.16854 /j.cnki.1000-0712.170651
    Abstract ( 1891 )   PDF (587KB) ( 1548 )  
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    Using the variable-separated method,the exact solution of relationship between temperature and time inside a finite length energized cylinder under the second kind and third kind boundary conditions is obtained, and through the simulation by COMSOL multi-physics software of computers,the distribution diagrams of temperature inside the cylinder are also presented. It is found that the simulation results of the surface temperature and inner temperature of the cylinder are corresponded with the experiment values,the maximum temperature of the simulation results and experiments are almost the same,which agree with the prediction of the analytic solutions.
    The forces of the uniform charged linear and conductor
    LIAO Qi-li,DENG Ya,YU Yan,LIU Li-xin
    College Physics. 2018, 37(8):  19-23.  doi:10.16854 /j.cnki.1000-0712.170645
    Abstract ( 1427 )   PDF (1571KB) ( 505 )  
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    We calculate the Coulomb forces of the uniformly charged linear body and the conductor flat connecting with earth or the electric conductor ball reaction with the mirror image method in the electromagnetic theory.The superposition principle and mathematical software“Mathematica” can be used,thus the Coulomb forces of the image changing with angle and distance are given.
    Research on electric properties of an n-step Fan network
    TAN Zhi-zhong,WU Peng,LUO Xiao-lian,KONG Ze-lin
    College Physics. 2018, 37(8):  24-28.  doi:10.16854 /j.cnki.1000-0712.170560
    Abstract ( 887 )   PDF (337KB) ( 282 )  
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    The electrical properties (including the voltage of any node,and equivalent resistance) of a class of n-step Fan resistor network are studied,and innovation in theory and method has been achieved. In this paper,the second-order difference equation model and the boundary condition equation model are established by using the node potential as the variable in terms of applying Kirchhoff's law. By studying the general solution and special solution of difference equation,the voltage formula of arbitrary node of n-order Fan network is obtained,at the same time,the equivalent resistance formula between any two nodes is obtained as well,and the special situation of the conclusion is analyzed and discussed. Our research work realizes the cooperation and mutual benefit between teaching and scientific research.
    A study on the virtual image position of an object point in water and its change rule with the angle of view
    SHAO Yun,DOU Jin
    College Physics. 2018, 37(8):  29-30.  doi:10.16854 /j.cnki.1000 0712.170714
    Abstract ( 1692 )   PDF (403KB) ( 781 )  
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    A formulaic solution,i.e.,derivative method,which is more simple and direct than that in the traditional textbook,is put forward for the virtual image coordinates of an object point in water,and the virtual image point and its trajectory equation with the changes of view are obtained. Thus the trajectory is made in the rectangular coordinate system. Meanwhile,a certain amount of interpretations are given to these results.
    Calculation of the ground state energies of the second period atoms by Bohr theory
    MENG Li-juan,WU Feng
    College Physics. 2018, 37(8):  31-34.  doi:10.16854 /j.cnki.1000-0712.180022
    Abstract ( 1643 )   PDF (510KB) ( 561 )  
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    By using Bohr theory combined with qualitative analysis,the ground-state atom structures of the second period atoms are constructed,and then the ground-state energies of these atoms are evaluated. The calculation is simple and the calculated energies are in agreement with experiment.
    Measurement of polarization properties of GaN based laser diode by Malus’Law
    FENG Lie-feng,LIU Jing-jin,CHENG Li-yan
    College Physics. 2018, 37(8):  35-38.  doi:10.16854 /j.cnki.1000 0712.170617
    Abstract ( 1972 )   PDF (1006KB) ( 927 )  
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    Based on Marius’s law in the“Physics of University Physics”,the polarization characteristics of GaN-based semiconductor lasers are studied accurately by self-built experimental platform. The experimental results show that after the lasing threshold,the GaN-based semiconductor laser has a higher degree of polarization and it is close to 1. At 5 mA far below the lasing threshold the polarization degree is close to 0.70,and it is already close to 0.93 at 27 mA below the threshold. This shows that not only the spontaneous emission with no degree of polarization but also the linearly polarized light with the same polarization direction as the threshold exists in the light emission of the GaN-based semiconductor laser far below the lasing threshold,and the ratio of this linearly polarized light in the total light intensity is very high.
    Application of recoil electron spectrum to γγ coincidence measurement
    PENG Hai-bo,LIU Feng-fei,ZHANG Qian,GUAN Ming,SUN Meng-li
    College Physics. 2018, 37(8):  39-43.  doi:10.16854 /j.cnki.1000 0712.180062
    Abstract ( 2135 )   PDF (729KB) ( 553 )  
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    A coincident technique is a normal technique which has extensive applications in fields of nuclear physics,basic physical parameter measurements and material science. The influence of recoil electron on the coincident count rate is discussed. Count rate of real coincident from gamma-gamma coincidence changes with threshold in conditions of high and low background. The experimental result suggests that spectrum from recoil electron could increase count rate of real coincidence,the count rate of total coincidence would be affected by the count from background in conditions of high and low background. The effect from the background could be deduced by data correction.
    Practice of arts physics in Shandong University
    YU Shu-yun,LIU Jian-qiang
    College Physics. 2018, 37(8):  44-46.  doi:10.16854 /j.cnki.1000-0712.170673
    Abstract ( 2086 )   PDF (537KB) ( 439 )  
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    Learning physics is an effective way to improve the scientific quality of art students.How to arrange the course content and teaching method for art students are two main questions.In this paper,the design of course content,the teaching method and teaching result of arts physics in Shandong University are introduced in detail.The results show that the content combined with everyday life and high technologies can attract the students.Moreover,the multiple teaching methods are welcomed by the students.
    Dynamical mechanism of coupling metronomes placed in parallel
    JIN Shan,LV Jian-feng
    College Physics. 2018, 37(8):  47-53.  doi:10.16854 /j.cnki.1000-0712.170680
    Abstract ( 2133 )   PDF (2386KB) ( 609 )  
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    Synchronous behavior is a ubiquitous phenomenon in nature.Under certain conditions,a number of mechanical metronomes,which are given an arbitrary initial phase,will reach the synchronized state of motion after a period of time. In this paper,firstly,we establish the dynamic equation of a single metronome by analyzing its internal working mechanism.According to the experimental results,the laws of the change of the resistance moment and the dynamic moment with time are given.Then the coupling action between the metronome is represented by the inertial force,so the dynamic equation of the metronome system is established with much more clear physical meaning which can better explain the synchronization phenomenon of the metronomes with the same swinging period on the horizontal board.The theory can be used to predict the time of the metronome system to achieve the synchronization,meanwhile,this theory model shows the good universality under different experimental conditions.
    Theoretical analysis of Michelson interference patterns under extended light source
    HUANG Lei,LIU Wei,SHI Qing-fan
    College Physics. 2018, 37(8):  54-57.  doi:10.16854 /j.cnki.1000-0712.170564
    Abstract ( 1541 )   PDF (662KB) ( 946 )  
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    A new theoretical explanation is proposed for the Michelson interference pattern under the extended light source.The light emitted by the extended light source,due to the reflection of the two mirrors,there are two virtual images of the corresponding light source.The light emitted by the two virtual images is transmitted on the screen with the light from the original light source through the beam splitter,the screen forms an equivalent interference.Through this interpretation,we can more clearly understand the process of the process of the circle,oval,curve,straight lines and other stripes.
    Doppler effect of high frequency wave on uniform circular motion
    KE Wei,WANG Cheng,GUO Zhen-ping
    College Physics. 2018, 37(8):  58-64.  doi:10.16854 /j.cnki.1000-0712. 70403
    Abstract ( 2036 )   PDF (1205KB) ( 491 )  
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    According to the characteristics of uniform circular motion,the Doppler effect of high frequency wave for three different motion states,such as wave source fixation and observer movement,wave source motion and observer fixation,both wave source and observer movement,are discussed,respectively.The generalization of both wave source and observer move in different circle and direction of different circular motion is derived in different relative motion state to receive the wave frequency formula.The results show that the frequency of the received wave is periodically changed in the uniform circular motion state,and the frequency of the received wave's frequency change is positively correlated with the absolute value of the angular velocity difference of the wave source observer. The magnitude of the received wave frequency is affected by the angular velocity difference,the absolute value,the observer's radius of motion and the wave velocity,but the effect is different,while the extreme point position is affected by the wave source radius of motion.