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    20 October 2016 Volume 35 Issue 10
      
    Gravitational wave and general relativity
    ZHAO Zheng1),LIU Wenbiao1),ZHANG Xuanzhong2)
    College Physics. 2016, 35(10):  1-10.  doi:10.16854/j.cnki.1000-0712.2016.0139
    Abstract ( 1712 )   PDF (6120KB) ( 2088 )  
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    Abstract:The theory about gravitational wave is introduced based on the general relativity.We introduce how to detect indirectly gravitational radiation by means of the time rate variation of the period of binary star and how to directly detect gravitational waves by means of the polarization of the wave.
    Work-energy theorem for systems with time related force field and its application
    ZHU Ru zeng
    College Physics. 2016, 35(10):  11-16.  doi:10.16854/j.cnki.1000-0712.2016.0140
    Abstract ( 1275 )   PDF (789KB) ( 591 )  
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    The work -energy theorem for systems with time related force field possessing potential and other forces has more powerful application value than the ordinary work-energy theorem.This paper plans to introduce the former and apply it to judge whether the mechanical energy relative to different reference systems is conservative for two simple systems:a particle in the gravity field and a light spring oscillator with one end fixed in the moving compartment.
    Numerical study of the magnetic field of the charged solenoid
    MA Zengwei,WANG Zhiyong,WEI Jianwei,LIU Gaiqin,HU Nan,LI Ruifeng
    College Physics. 2016, 35(10):  17-19.  doi:10.16854/j.cnki.1000-0712.2016.0141
    Abstract ( 1493 )   PDF (1421KB) ( 813 )  
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    Based on the Boit-Savart law,the concepts of effective radius,effective spatial location and effective spatial orientation are introduced by comparing the far-field approximate calculation of charged current loops and the dipole magnetic field with the strict calculation of the magnetic field of the solenoids. By optimizing the solenoid structure and rebuilding,the computing model can overcome the limited length effect of the spatial magnetic field brought by the solenoid itself effectively. By simulating the system within the effective region,the result shows that the far-field approximate calculation of the dipole magnetic field not only meets the accuracy in magnetic field calculation but also has very fast calculation speed. The method can realize the magnetic calculation with the complex structure from many solenoids in real time and satisfy the real-time requirement of spatial positioning and electromagnetic navigation.
    Gay-Berne interaction potential used in coarse-graining molecular simulation
    MAO Yingchen,ZHANG Depeng,LIU Jiahui,SUN Meng,WANG Shijia
    College Physics. 2016, 35(10):  20-22.  doi:10.16854/j.cnki.1000-0712.2016.0142
    Abstract ( 1419 )   PDF (1209KB) ( 516 )  
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    How to compute effectively the interactions of non-spherical coarse-graining particles is critical for the improvement of computational speed of the coarse-grained molecular simulation,so we introduce Gay-Berne potential in this paper,and carry out applications for two small organic molecular systems. We derive the GB parameters of coarse-graining particles with genetic algorithm based on the reasonable conformational set. Moreover,we make some tests about the GB parameters through making comparison with the results from coarse-grained model and all-atom model,respectively. Finally,we point out how to deal with the interaction site is an essential problem for the development of coarse-graining model.
    The sufficient conditions for the spring’s static deformation and gravity acceleration vanishing from the intrinsic frequency expression of a vibrator
    CHEN Kuifu,CAI Chun
    College Physics. 2016, 35(10):  23-27.  doi:10.16854/j.cnki.1000-0712.2016.0143
    Abstract ( 1537 )   PDF (1100KB) ( 808 )  
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    Vibration teaching practice employs a plenty of such kind of examples with the gravity and spring’s static deformation not contributing to intrinsic frequencies. However,there exist indeed counter examples with the gravity and spring’s static deformation playing a role. We investigate the if-and-only-if conditions for the spring’s static deformation and gravity acceleration vanishing from the intrinsic frequency expression. Theoretical analysis shows that the spring’s static deformation vanishes from the intrinsic frequency expression if the spring axis is tan gential to the particle trajectory at the static balance position. With this condition satisfied,the gravity acceleration vanishes from the intrinsic frequency expression if the particle trajectory transgressing the static balance position is   either vertical or zero curvature. The conclusion is not only benefit to comprehend the significance of the gravity to the intrinsic frequency,but also useful in compiling and creating new examples for vibration teaching practice.
    Deriving the average relative speed of gas molecules with the isotropy
    ZHENG Yong
    College Physics. 2016, 35(10):  28.  doi:10.16854/j.cnki.1000-0712.2016.0144
    Abstract ( 1480 )   PDF (721KB) ( 942 )  
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    The relative velocity distribution of molecules of ideal gas is found to possess the same function form as the velocity distribution,which is due to the similar statistical properties they satisfy.The constant in this function is difficult to determine for the former and we have completed this by employing a familiar relation which generally being used in an approximate discussion of the average relative velocity. Then the average relative velocity is calculated.
    Numerical study of the magnetic field of the charged solenoid
    XIANG Qian,WANG Shiqing,LI Zicheng,LI Xinghong,HOU Jingjing
    College Physics. 2016, 35(10):  29-34.  doi:10.16854/j.cnki.1000-0712.2016.0145
    Abstract ( 1104 )   PDF (2330KB) ( 513 )  
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    Based on the Boit-Savart law,the concepts of effective radius,effective spatial location and effective spatial orientation are introduced by comparing the far-field approximate calculation of charged current loops and the dipole magnetic field with the strict calculation of the magnetic field of the solenoids. By optimizing the solenoid structure and rebuilding,the computing model can overcome the limited length effect of the spatial magnetic field brought by the solenoid itself effectively. By simulating the system within the effective region,the result shows that the far-field approximate calculation of the dipole magnetic field not only meets the accuracy in magnetic field calculation but also has very fast calculation speed. The method can realize the magnetic calculation with the complex structure from many solenoids in real time and satisfy the real-time requirement of spatial positioning and electromagnetic navigation.
    Discussion on the measurement of cardinal points of a compound lens using nodal slide
    LIU Qiuwu
    College Physics. 2016, 35(10):  35-38.  doi:10.16854/j.cnki.1000-0712.2016.0146
    Abstract ( 1156 )   PDF (822KB) ( 677 )  
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    The cardinal points play an important role in the geometrical optics. The spread of optical imaging is analyzed when a collimated light beam passes through a compound lens,then the image rule is discussed when the rotational axis of the nodal slide does not coincident with the image nodal point,and the measurement method of cardinal points of a compound lens is presented. These can be used to deepen students ’ comprehensive understanding of the cardinal points of compound lens and measurement with nodal slide.
    Teaching exploration of expanding comprehensive experiment of photovoltaic cell
    XIAO Wenbo,YAN Chao,ZHANG Huaming,WANG Qin
    College Physics. 2016, 35(10):  39-41.  doi:10.16854/j.cnki.1000-0712.2016.0147
    Abstract ( 1419 )   PDF (2673KB) ( 813 )  
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    The measuring electrical characteristics of solar cells are now routine experimentation in all university. The main content is a preliminary analysis and research of I-V characteristics. In order to expand the experiment content and further develop student’s ability,a new experiment is designed. In the new experiment,the five solar cell internal parameters (series resistance etc.)which can be used to evaluate the cell’s performance, are extracted. The results show that the cell’s current depends on the temperature weaker than its voltage. In addition,it is found that the temperature has minimal impact on the cell’s series resistance and a maximum impact on the cell’s reverse saturation current. This experiment can not only help students to master I-V characteristics and its temperature dependence,but also help students understand the temperature dependence of photovoltaic cell interior intrinsic parameters. This experiment can also cultivate students’ability to analyze and solve problems.
    Investigation on measuring fine constant of confocal spherical scanning interferometer
    YANG Xiaodong,YU Quanbao,LV Runjia
    College Physics. 2016, 35(10):  42-45.  doi:10.16854/j.cnki.1000-0712.2016.0148
    Abstract ( 1265 )   PDF (956KB) ( 701 )  
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    A scheme of measuring fine constant of confocal spherical scanning interferometer is suggested. In the scheme,the time of scanning the neighboring transmission peak Δt2π and scanning phase half width of one transmission peak Δtφ are measured by the use of oscillograph,and the fine constant of confocal spherical scanning interferometer equals to the ratio of Δt2π and Δtφ . Based on the scheme,the fine constants are measured under different scanning frequency and voltage. The measuring results show that,under different scanning frequency and voltage,the measured fine constants all are close to the theory value of the confocal spherical scanning interferometer provided by the manufacturer,the present measuring scheme is reliable and feasible. Furthermore,it is analyzed in heory that the measured Δt2π and Δtφ are inversely proportional to the scanning frequency and voltage of the saw tooth wave inputting to the confocal spherical scanning interferometer.
    Thinking and practice on teaching reform of physics experiment course for medical specialty
    KA Weibo,SUN Dagong,YUAN Guihong,LI Hui,DENG Dening
    College Physics. 2016, 35(10):  46-51.  doi:10.16854/j.cnki.1000-0712.2016.0149
    Abstract ( 1179 )   PDF (756KB) ( 490 )  
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    The current situation of physical experiment courses in domestic medical specialty is analyzed,and an education reform practice of the physics experiment course of Peking University Health Science Center is introduced. Directed by the idea of “adhering to the basic of physics,increasing the contemporary contents,combining with applied medicine”,a ten-year education reform practice results in a new physical experimental course. This course emphasizes both medical applications and physics,and places value on both modern technology and hands on operation. It turns out that students show more interest to this physical experiment. A suggestion is put forward that emphasis should be laid on the basic of physics in the physics course construction and teaching reform for medical specialty.
    Discussion on methods of measuring the dispersion relation of water wave
    YANG Hong,QIAO Kaiyao,RUAN Chengzong
    College Physics. 2016, 35(10):  52-55.  doi:10.16854/j.cnki.1000-0712.2016.0150
    Abstract ( 1567 )   PDF (2244KB) ( 672 )  
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    We introduce a water wave measuring device which is controlled by LabVIEW. Three methods such as standing wave method,phase of traveling wave method and Doppler effect method can be used to measure the dispersion relation of water wave. We compare the advantages and disadvantages of these three methods and put forward some recommendations for improvements.
    Measurement of the crosssectional energy density   distribution of intense pulsed ion beam
    LI Dongyu,YU Xiao,SHEN Jie,QU Miao,ZHONG Haowen, ZHANG Jie,ZHANG Gaolong,YAN Sha,LE Xiaoyun
    College Physics. 2016, 35(10):  56-60.  doi:10.16854/j.cnki.1000-0712.2016.0151
    Abstract ( 1134 )   PDF (3017KB) ( 470 )  
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    The crosssectional energy density distribution of intense pulsed ion beam is of great significance to   beam characterization and application.Using infrared imaging diagnostic techniques,the crosssectional distribution   analysis of IPIB is achieved with high spatial and energy density resolution.With this method the measurement of the   beam focus and the beam transmission characteristics analysis are carried out.This diagnostics can be used to make   further understanding of the working principles of intense pulsed accelerator and master the basic skills in carrying   out diagnostics to powerful pulsed beams.
    The Center for Studies of Song History,Hebei University,Baoding,Hebei 071002,China
    HOU Yude
    College Physics. 2016, 35(10):  61-65.  doi:10.16854/j.cnki.1000-0712.2016.0152
    Abstract ( 1187 )   PDF (552KB) ( 549 )  
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    Physicists and historians of science all consider that the observable principle was very important for creating quantum mechanics. Following the publication of Heisenberg’s “one person paper”in 1925,most of thebooks and papers related to the history of quantum mechanics have indicated that the observable principle was a great contribution from Heisenberg. In fact Heisenberg was not the physicist who first presented observablity. Max Born had already clear described the idea in his book published in 1920,and he also repeated it frequently to Landé when he was the professor in Frankfurt,from 1919 to earlier 1921. A lot of evidence could prove that Heisenberg learned the observable principle from Gttingen,directly from professor Max Born.