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    20 February 2018 Volume 37 Issue 2
      
    From the gravitational wave detection to multi-messenger astronomy
    CAO Zhou-jian
    College Physics. 2018, 37(2):  1-9.  doi:10.16854 /j.cnki.1000-0712.170626
    Abstract ( 1477 )   PDF (355KB) ( 768 )  
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    LIGO successfully got the first gravitational wave detection on September 14,2015. This result was anounced on February 11,2016. And this event is named GW150914. Afterwards gravitational wave detection develops very fast. So far gravitational wave events resulted from binary black hole merger have been detected 4 times, including GW150914,GW151226,GW170104 and GW170814. One gravitational wave event resulted from binary neutron star merger,GW170817,has also been detected. In addition one more detection from binary black hole merger,LVT151012,has been recorded. Inspired by the gravity wave detection, the research on gravitational wave physics and gravitational wave astronomy has developed very fast since 2016. This paper makes a brief introduction and discussion on the detection of gravitational waves and gravitational wave astronomy especially in the theoretical physics respect.
    On the unitary operator for mutual transformation between coordinate and momentum representations
    ZHAN De-hui1,LU Dao-ming1,FAN Hong-yi2
    College Physics. 2018, 37(2):  10-11.  doi:10.16854 /j.cnki.1000-0712.170510
    Abstract ( 1626 )   PDF (192KB) ( 683 )  
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    By using the integration within ordered product of operators,we derive the unitary operator for generating the mutual transformation between coordinate and momentum representation,then we apply it to the fractional Fourier transform.
    Introduction to dimensional analysis( continuation-2)
    LIANG Can-bin1,CAO Zhou-jian2,CHEN Zhi-tao3
    College Physics. 2018, 37(2):  11-17.  doi:10.16854 /j.cnki.1000-0712.170262-2
    Abstract ( 1294 )   PDF (542KB) ( 817 )  
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    A novel and systematic dimensional analysis is presented. A few new concepts such as“quantity class”and“class of unit systems”are coined,and a clear cut definition of“dimension”is provided. A self-contented proof of the Π theorem is presented based on these new concepts,and two examples illustrating the great power of the theorem are also given.
    Methods of physical cognition
    MU Liang-zhu
    College Physics. 2018, 37(2):  18-21.  doi:10.16854 /j.cnki.1000-0712.170366
    Abstract ( 1462 )   PDF (452KB) ( 745 )  
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    Various physical methods are extracted from the process of physical cognition. These may be important in physics education and research.
    The motion of a particle on a non-smooth rotating disk
    YU Feng-jun
    College Physics. 2018, 37(2):  22-25.  doi:10.16854 /j.cnki.1000-0712.170060
    Abstract ( 1164 )   PDF (1512KB) ( 647 )  
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    The motion of a particle on a non-smooth rotating disk is studied. According to the force equilibrium condition and the Newton's law,the problem of the static condition,the trajectory and the law of motion of the particle are solved by means of numerical solution,qualitative and quantitative analysis in rotating reference system.
    Application of Fermat's principle in ideal imaging at the spherical boundary for the virtual image
    WAN Jian-jie
    College Physics. 2018, 37(2):  26-28.  doi:10.16854 /j.cnki.1000-0712.170171
    Abstract ( 1698 )   PDF (288KB) ( 790 )  
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    Fermat's principle is a basic principle in geometrical optics,which means that the actual trajectory in the space depends on the extremum of the optical path. Based on the Fermat’s principle,a new method has been given to directly obtain the equations for the practical optical path in reflections and refractions at spherical boundary for the virtual image,and then the object-image formula have also been derived in the condition of axial ray and axial object. The present results show the equations for divergent lines are different from those for convergent lines,but their object-image formula are very same.
    Airy wave packet and the auto acceleration effect( Continuation—2)
    KONG Hong-yan
    College Physics. 2018, 37(2):  29-33.  doi:10.16854 /j.cnki.1000-0712.170028-2
    Abstract ( 1190 )   PDF (1521KB) ( 668 )  
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    Combined with the Airy function and its basis properties,this article studies the microscopic motion of a wave packet of a particle in a linear potential field. The Schrdinger equations for the linear potential and the V potential are solved to give the wave functions and the energy level structure of the particle. Then,in the free space,the free motion of Airy package is investigated in detail. The calculation reveals that a free Airy wave packet shows a self-acceleration in the free space. Finally,some experiments to show the strange evolution of Airy wave packet are demonstrated.
    Simulation study of movement of charged particle in a magnetic mirror with gravity drift
    CHUEN Jun
    College Physics. 2018, 37(2):  34-37.  doi:10.16854 /j.cnki.1000-0712.170174
    Abstract ( 1134 )   PDF (1029KB) ( 681 )  
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    Based on the basic principle of electromagnetism,we discuss the distribution of magnetic field of the mirror constructed by two parallel current carrying rings,as well the relationship of magnetic flux conservation for the moving particle in uniform magnetic field. The gravity drift motion of particle in weak inhomogeneous magnetic mirror field is studied by using theoretical analysis and numerical method. Our results consist with the formula of gravity drift in magnetic field,which show that the existence of gravity violates the conservation of magnetic flux in weak magnetic field.
    Measurement of liquid complex refractive index based on prism ellipsometry
    WU Yi-dong,YUAN Kai-hua,HUANG Zuo-hua
    College Physics. 2018, 37(2):  38-41.  doi:10.16854 /j.cnki.1000-0712.160565
    Abstract ( 1161 )   PDF (477KB) ( 619 )  
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    By introducing isosceles prism,ellipsometry technique is used to measure the complex refraction index. Based on the principle of Fresnel formula and ellipsometry,the relationship between ellipsometric parameters measured by the instrument and ellipsometry parameters of the prism-liquid interface is analyzed theoretically. The precision of measuring the refractive index and the absorption coefficient of the liquid is also discussed. The water and Indian ink are measured by the null ellipsometer,and the experimental curves of the refractive index,the absorption coefficient between the concentration of the samples are obtained. The experimental results are basically consistent with the references. The experimental results show that the accuracy of the prism ellipsometry technique measuring the refractive index and absorption coefficient of the liquid are 0.0004 and 0.0003,respectively. The prism ellipsometry is suitable for rapid measurement.
    Insight of undergraduate training from the perspective of information physics
    HUANG An-ping,ZHANG Xing-jiang,XIAO Zhi-song
    College Physics. 2018, 37(2):  42-46.  doi:10.16854 /j.cnki.1000-0712.170501
    Abstract ( 1463 )   PDF (281KB) ( 414 )  
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    The advancement of information technology has made tremendous impact on varaiety of trades and professions,including university education,which has excited broad interests. Currently,the impact on university education is mainly in the technical level,such as reform of“Internet + education”and“Internet + teaching”reform.However,the quantum physics or quantum thinking behind the information technology has not drawn enough attention. From this point of view,this paper analyzes the physical characteristics of the development of information technology and give insights to the current university education. After that, the popularization of quantum physics and the necessity of quantum thinking in universities are disscussed and demostrated by our examples.
    Using computational means to enhance the level of college physics teaching
    DONG Jian
    College Physics. 2018, 37(2):  47-52.  doi:10.16854 /j.cnki.1000-0712.160381
    Abstract ( 1687 )   PDF (1144KB) ( 705 )  
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    “To pay attention to and improve the teaching level of foundmental college physics”,the slogan has   been proposed for many years,policy incentives,teacher demonstrations,and various measures have been implemented.   In the situation of physical knowledge growing considerably and physical problems becoming increasingly   complexity,the traditional teaching focus to illustrate the concepts of physics is facing the obsolete expressions,   lack of means to solve,not easy to expand the curriculum,difficult to deepen concepts,and many other teaching   insurmountable difficulties. This paper uses specific examples in the courses of mechanical,thermal,geometrical   optics and quantum mechanics,combining the convenience and power of Mathematica software,from aspects of solving   differential equations,updating the way of expression,expanding course content,overcoming difficulties of   knowledge and courses,deepening physics concepts,etc,to discourse the necessity and possibility of introducing   computing means to enhance the teaching level of college physics.
    New sensor carrier—review of smartphone in physics experiment
    LI Xi-jun,CHENG Min-xi,JIANG Min-li
    College Physics. 2018, 37(2):  53-59.  doi:10.16854 /j.cnki.1000-0712.170138
    Abstract ( 1581 )   PDF (1847KB) ( 1503 )  
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    The development history of smartphone sensor experiments is reviewed. Different types of experiments are introduced and the advantages of smartphone sensor are summarized. The development prospect of experiments based on smartphone sensor is discussed
    On the movement of small ball under the action of "Centrifugal Buoyancy"
    LIU Jie1,PANG Guo-ying2,LIU Jun2,YU Qing-han1
    College Physics. 2018, 37(2):  60-63.  doi:10.16854 /j.cnki.1000-0712.170205
    Abstract ( 1583 )   PDF (385KB) ( 645 )  
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    The dynamic effect of the fluid in the constant rotation of the fluid is different from that of the stationary state. It is mainly embodied in the change of the pressure inside the liquid and the additional buoyancy,which can be called " centrifugal buoyancy" . We discuss V-shaped tube inertial centrifugal force demonstration instrument in the depth of the ball movement in-depth discussion,by solving the surface integral obtained by " centrifugal buoyancy" formula. Then we find the equation of motion and the phenomenon of quantitative analysis of the interpretation of the experiment.
    Application of Schlieren system in visualization of ultrasonic wave and velocity measuring
    HU Bin1,XIA Xun2,XIONG Chang3,ZHANG Bo-yi4,TANG Fang3,LI Chao-rong3
    College Physics. 2018, 37(2):  64-67.  doi:10.16854 /j.cnki.1000-0712.170430
    Abstract ( 1577 )   PDF (1164KB) ( 1226 )  
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    A new method of ultrasonic wave velocity measuring by the Schlieren system is discussed. It is convenient to observe the ultrasonic wave spreading in the acoustic-optic medium. Meanwhile,an image of the periodic istribution of the refractive index can be shown on the observation screen under some circumstance,which can be used to calculate the ultrasonic wave velocity in the medium. This new method of velocity measuring helps to have a vivid understanding of the spreading of ultrasonic wave in the acoustic-optic medium.
    Diffractive ultrasonic lens
    YU Jia-xi
    College Physics. 2018, 37(2):  68-70.  doi:10.16854 /j.cnki.1000-0712.170247
    Abstract ( 1504 )   PDF (691KB) ( 573 )  
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    Based on Kirchhoff diffraction theory and Fresnel zone-plate theory,an ultrasonic lens is designed and produced. This lens successfully focused acoustic wave in the experiments,while simulations precisely described experiments' results. When the distance between lens and source ( D) or number of lens' rings ( N) is changed,the 1D acoustic distribution illustrated that the later is a more magnificent variance.
    Research on cut-set in the application of circuit analysis
    LIU Zhi-ang
    College Physics. 2018, 37(2):  71-74.  doi:10.16854 /j.cnki.1000-0712.170337
    Abstract ( 1599 )   PDF (221KB) ( 518 )  
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    The general approaches of circuit analysis are node voltage analysis and loop current analysis. Also, loop and node are concepts of graph theory. According to circuit analysis and graph theory,a new way called cut-set voltage analysis has been proposed and verified. In addition, the rules of cut-set voltage equations have been raised based on the rules of node voltage equations and loop current equations. The new approach not only avoids complex matrix operation and establishes the equations directly,but also contributes effectively to analyze circuit network from the angle of graph theory.
    Measurement of resistivity of porous materials based on Van der Pauw method
    LI Xiao-yi,YAN Mu-yu,CHEN Yun-lin,YAN jun
    College Physics. 2018, 37(2):  75-78.  doi:10.16854 /j.cnki.1000-0712.170192
    Abstract ( 2254 )   PDF (1161KB) ( 1591 )  
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    On the basis of Van der Pauw method,the Van der Pauw formula is simplified. Under the critical condition,the form of Van der Pauw formula is preserved,namely,the constant of the equation is modified and critical value is calculated. The complete method of measuring resistivity of single hole material is summarized. For the porous materials,the quantitative formula of field strength,current and resistivity are deduced. The problem is solved by software simulation,fitting quantitative and analogy method to find the distribution of field intensity and current value. The condition of application of the Van der Pauw method is extended.
    A trial function method in quantum mechanics
    Sharantuya,Naranmandula
    College Physics. 2018, 37(2):  79-81.  doi:10.16854 /j.cnki.1000-0712.170172
    Abstract ( 2146 )   PDF (184KB) ( 834 )  
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    A trial function method in quantum mechanics for solving Kummer-like equation,such as radial equations of two- ( 2D) or three ( 3D) -dimensional atom,radial equations of 2D and 3D harmonic oscillators and Tricomi equation are given. The extension of the trial function method is also presented.