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Table of Content

    20 March 2018 Volume 37 Issue 3
      
    The geometric approach to calculate radiation pressure and radiation energy passing density
    BAO Jing-dong
    College Physics. 2018, 37(3):  1-3.  doi:10.16854 /j.cnki.1000-0712.170485
    Abstract ( 2038 )   PDF (328KB) ( 1659 )  
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    By using the geometric method,two important formula in the radiation thermodynamics of the cavity are proved,namely,the relation between the radiation pressure and radiation energy density as well as the relation between the radiation energy passing density and the radiation energy density. The description and proving problems for the above two formula in the present textbooks are discussed.
    Revisit on the traditional variational calculation for the ground-state energy of 
    MENG Li-juan,WU Feng
    College Physics. 2018, 37(3):  4-5.  doi:10.16854 /j.cnki.1000-0712.170326
    Abstract ( 1251 )   PDF (222KB) ( 493 )  
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    The deficiency of traditional variational calculation for the ground-state energy of  is found and the reason is revealed,which is beneficial for better understanding the principle of variational method.
    An integral approach to electric field of charges on spherical surface with cosine distribution
    ZHANG Zhi-liang,ZHENG Yao,CHI Cheng,HU Bing-lu
    College Physics. 2018, 37(3):  6-8.  doi:10.16854 /j.cnki.1000-0712.170216
    Abstract ( 2194 )   PDF (345KB) ( 731 )  
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    The electric field of charges on spherical surface with cosine distribution ( σ=σ0cos θ) is solved by the integral method. By composition of the electric fields of the charge elements on the two surface area elements enclosed by a solid angle at the field point at first,the resultant fields can be easily obtained. The results are the same with the existing ones.
    The deduction from maximum power transfer to wireless power transfer
    GUO Yun-sheng
    College Physics. 2018, 37(3):  9-12.  doi:10.16854 /j.cnki.1000-0712.170463
    Abstract ( 1414 )   PDF (271KB) ( 623 )  
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    Starting from the maximum power transfer theorem,we deduce gradually the circuit principle and characteristics of the magnetic resonant coupling wireless energy transmission,then the same conclusion as reported in an article published in Science is obtained. It is shown that the mechanism of the magnetic resonant coupling wireless energy transfer is still in the domain of circuit theory. It also demonstrates that digging in depth and applying creatively the important contents,appeared in basic courses,can play a role in accurately understanding and explaining the new phenomena reported in the scientific foreland.
    The electric field of a line charge and a grounding plane conductor with straight gap and its numerical simulation
    JIA Lan-fang,WANG Fu-qian
    College Physics. 2018, 37(3):  13-15.  doi:10.16854 /j.cnki.1000- 0712.170151
    Abstract ( 1291 )   PDF (1275KB) ( 419 )  
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    By means of theoretical analysis combining with computer numerical simulation,we study the electric field of a line charge and a grounding plane conductor with straight gap by using the conformal mapping.The electric field line and equi-potential line are plotted by MATLAB.
    Discussion on amplitude and intensity of o and e lights and transmitted light in a wave wafer
    YIN Bao-yin,LI Jin-ping
    College Physics. 2018, 37(3):  16-19.  doi:10.16854 /j.cnki.1000-0712.170232
    Abstract ( 1831 )   PDF (451KB) ( 618 )  
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    Based on the Fresnel formula,the general amplitude and intensity of ordinary light ( i.e. o-light) and extraordinary light ( i.e. e-light) from a linear polarized beam incident in a wave wafer under considering reflection without absorption are obtained,and further discussion and concrete comparisons from a linear polarized beam vertical incident in a wave wafer are presented. In addition,the amplitude,intensity and transmission rate after the light penetrating wave wafer are discussed. In comparison with the amplitude and intensity without considering the reflection given by dominating textbooks,we have found that there are not only numerical differences but also differences in knowledge content.
    Numerical calculation and simulation analysis of two-dimensional lattice vibrations
    XU Long,YANG Jun
    College Physics. 2018, 37(3):  20-22.  doi:10.16854 /j.cnki.1000-0712.170276
    Abstract ( 1748 )   PDF (526KB) ( 1411 )  
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    based on the two -dimensional square lattice for example,we analyze the relations of the closest atom approximate dispersion,which is based on the discussion about the dispersion relation of one-dimensional lattice and lattice heat capacity. The numerical result has been presented by Matlab.
    The group theory approach to vibration mode of W( CO)6 molecule
    KUANG Xiang-jun,JIA Lian-bao
    College Physics. 2018, 37(3):  23-25.  doi:10.16854 /j.cnki.1000-0712.170314
    Abstract ( 1621 )   PDF (348KB) ( 708 )  
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    Based on the high symmetry of W( CO)6 molecule and the group theory method,the vibration mode and vibration spectrum activity are analyzed. We get the bond-length,electron cloud distribution and 13 different vibration frequencies for W( CO)6 molecule by using the Demol program package based on the density functional theory.
    What are the spirits of physicists
    MU Liang-zhu
    College Physics. 2018, 37(3):  26-28.  doi:10.16854 /j.cnki.1000-0712.170436
    Abstract ( 1731 )   PDF (374KB) ( 706 )  
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    Typical spirits of physicists are extracted from the process of physical cognition. These may be important in physics education and research.
    Measuring refractive index of liquids by back focal plane imaging
    QIU Dong1,ZHU Wei2,ZHANG Dou-guo1
    College Physics. 2018, 37(3):  29-32.  doi:10.16854 /j.cnki.1000-0712.170289
    Abstract ( 1653 )   PDF (521KB) ( 737 )  
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    A layer of gold film is deposited on glass substrate by magnetic sputtering and different concentrations of sodium chloride solutions are drop on gold film as test samples. Refractive of sodium chloride solution is obtained by analyzing the coupling of light and surface plasmon produced on the interface of gold film and liquid,the relative position of dark ring in the back focal plane,and the theory of surface plasmon. Experimental error is calculated and the method of improving the measurement precision is proposed. This experiment combined micro and nano fabrication with the back focal plane imaging process,which has been developed a new way to measure refractive index of liquids and then has important applications in material analysis and sensor.
    Refractive index measurement of transparent materials based on PASCO platform
    JIN Yuan-wei1,WANG Ya-bing2,3,WU Qing-chun1,WANG Lian-cheng1,ZHAO Bin1
    College Physics. 2018, 37(3):  33-37.  doi:10.16854 /j.cnki.1000-0712.170238
    Abstract ( 1214 )   PDF (1526KB) ( 707 )  
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    Based on the Michelson interferometer and the PASCO experimental platform,a method for the refraction index measurement of transparent materials,with high precision and high efficiency,is described. Firstly,the basic theory of the Michelson interferometer is analyzed. Secondly,the high-performance PASCO sensor and computer are used to capture and process the interference fringes,and the corresponding refractivity is calculated.Finally,the factors affecting the measurement uncertainty are given. The experimental results show that the measurement of the rotation angle θ affects the refractive index precision most,the thickness d does less,and the interference fringes’counting K does the least. The PASCO platform,in combination with the Michelson interferometer, can accurately and efficiently record the change of light intensity during the interference fringe turnover process,and then improve the calculation accuracy of the corresponding refractive index by reducing the uncertainty of the fringe counting. Also,the method can be used for the measurement of other properties related to the refractive index of the transparent materials.
    Experiential study of optical tunneling
    XIONG Ze-ben1,MA Shi-hong2
    College Physics. 2018, 37(3):  38-43.  doi:10.16854 /j.cnki.1000-0712.170041
    Abstract ( 1473 )   PDF (838KB) ( 936 )  
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    The historical background and extensive application of the optical tunneling effect are reviewed. Meanwhile,theoretical evidences of the evanescent field and its properties field are analyzed. Through the review and the analysis,the corresponding evanescent wave transmittance formula is obtained. Theoretically,the relationship between transmittance and the thickness of the gap,the relationship between the wavelength of the incident light and the angle of incidence are imitated. Experimentally,the relationship between the transmittance and the thickness of the gap is proved to exist.
    Thermal light ghost imaging with a projector in the multimedia classroom
    LIU Jiang-tao1,2,3,TONG Hong1,LI Wei-min1,XIAO Wen-bo4,ZHANG De-jian2
    College Physics. 2018, 37(3):  44-47.  doi:10.16854 /j.cnki.1000-0712.170429
    Abstract ( 1534 )   PDF (944KB) ( 465 )  
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    “Ghost”imaging,also known as correlated imaging or quantum imaging,is a kind of new imaging technology based on the correlation function between the reference light field and target light field. Using the nega-tive imaging method,we achieve successfully the thermal ghost imaging in the multimedia classroom. It has been found that the ghost imaging using the negative imaging method can be realized with low system resources. The re-quirement for the brightness of the light source can be reduced by about four times. When the projector’s brightness is 1200 lumens or the background brightness is 450 lumens,a clear ghost image can be obtained; most multimedia classrooms can easily meet these requirements. This study not only can introduce the forefront techniques in quan-tum optics research field into the classroom as a demonstration experiment,but also stimulate students’interest in learning. In addition,it can also promote the ghost imaging out of the lab and extend its practical application.
    Interactive behavior analysis in blended collaborative learning of college physics
    HU Cui,ZHANG Rui,WANG Zu-yuan
    College Physics. 2018, 37(3):  48-54.  doi:10.16854 /j.cnki.1000-0712.170367
    Abstract ( 1198 )   PDF (722KB) ( 445 )  
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    Based on the practice of the blended collaborative learning in College Physics course, the quality of interactive content is established according to Bloom's taxonomy of educational objectives in the cognitive domain.It has been found that students' learning achievement in blended collaborative learning is strongly correlated with the quantity of online interaction and the quantity of conventional classroom high quality interaction, the quantity of conventional classroom interaction is weakly related to student learning achievement.
    Relationship between physical parameters in doped semiconductors by GUI
    XU Yue-hua,ZHANG Jia-zhen
    College Physics. 2018, 37(3):  55-62.  doi:10.16854 /j.cnki.1000-0712.170394
    Abstract ( 1724 )   PDF (3779KB) ( 1256 )  
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    The Fermi energy level varies with the temperature is the central issue of the conductivity in the semiconductor materials. The relationship between the Fermi energy level and the temperature is complex,because it contains multiply parameters. Furthermore,in that relationship the Fermi integral can not be calculated manually.In this paper,we use the Simpson numerical method to deal with the Fermi integral,then take advantage the powerful matrix computing capabilities and interface design function of MATLAB software to set up a GUI interface.Specifically,we can set parameters according to the N-type,P -type and mixed doping under different circumstances,demonstrate the variation of Fermi energy level and carrier concentration with temperature. So that the students taking semiconductor physics course can obtain a more intuitive and systematical learning experience and teachers can also remarkable improve classroom teaching efficiency.
    Generating three-dimensional Maxwell distribution using Monte Carlo method
    MO Yu-yu,LI Sheng-zhi
    College Physics. 2018, 37(3):  63-68.  doi:10.16854 /j.cnki.1000-0712.170297
    Abstract ( 2388 )   PDF (1305KB) ( 1351 )  
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    Generating two-dimensional Maxwell distribution using Monte Carlo method has already been presented in some numeric textbooks.Putting three-dimensional spherical surface random vectors in the process that representing the collision between molecules three-dimensional Maxwell distribution can thus form.The corresponding code is in MATLAB language and the comparison between the numerical result and the theoretical expectation is made.
    Solution and visualization of constraint reaction force on orbit based on Mathematica
    SHENG Yong,GUO Qin,JIN Li-fu
    College Physics. 2018, 37(3):  69-73.  doi:10.16854 /j.cnki.1000-0712.170267
    Abstract ( 1301 )   PDF (623KB) ( 675 )  
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    By using the differential equation of motion of natural coordinate system,a moving ringlet is studied, which is restricted on a parabola shaped orbit ( about x axisymmetric) and on an ellipse shaped orbit respectively.The expression of the constraint reaction force of a ringlet is obtained when it moves to any position. Then the solution is visualized by Mathematica software and the variation law of the constraint reaction force is shown intuitively.Research shows that the constraint reaction force of a parabola shaped orbit is asymmetric. Meanwhile,the constraint reaction force of two shaped orbits concerns the parameters of the orbit,the initial velocity,and the position.The influence of these parameters on the position of the extreme point of the constraint reaction force is also discussed. These results can be applied in engineering design.
    Several methods of band gap modulation of one-dimensional photonic crystal
    ZHANG Chan-chan,XIANG Feng-hua
    College Physics. 2018, 37(3):  74-77.  doi:10.16854 /j.cnki.1000-0712.170418
    Abstract ( 1119 )   PDF (719KB) ( 721 )  
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    Based on the transmission matrix method, the reflection spectrum of TiO2-SiO2 photonic crystal has been simulated by the MATLAB software.Under the conditions of the optical thickness of the medium meeting the1 /4 film, the influences of incident angle,dielectric thickness and the number of cycle on the band gap are discussed.It is found that the modulation of photonic band gap can be realized by changing the incident angle, the dielectric thickness and the number of cycle.
    The properties of energy spectrum in a non-Hermitian system with PT-symmetry
    ZHAN Guo-hui,YU Dian-qiang,WANG Zhi-zhen,ZHANG Lian-lian,GONG Wei-jiang
    College Physics. 2018, 37(3):  78-81.  doi:10.16854 /j.cnki.1000-0712.170155
    Abstract ( 1857 )   PDF (327KB) ( 1402 )  
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    We study the effect of the PT-symmetric complex potentials on the energy spectrum of one-dimensional non-Hermitian systems.By solving the energy spectrum,we find that potentials can give rise to degeneracy of energy,when the potentials are high enough.For the case of weak potential, the perturbation theory is used to analyze the energy spectrum.It is believed that the results of this work are helpful in understanding the properties of energy pectrum in PT-symmetric non-Hermitian systems.