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Table of Content

    20 August 2010 Volume 29 Issue 8
      
    著者文摘
    Hua Luo-geng(Hua,L.K.) and Einstein's special relativity with its extensions——In memory of the 100th anniversary of the birth of Hua Luo-geng
    . 2010, 29(8):  1-1. 
    Abstract ( 935 )   PDF (1240KB) ( 829 )  
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    By means of matrix geometry and projective geometry,Hua Luo-geng studied and simplified the principles of Einstein's special relativity,found the symmetry of inertial motion and promoted the research on de Sitter invariant special relativity.His very deep considerations on these issues have guided us till now how to face the challenges from precise cosmology for Einstein's theory of relativity as foundation of cosmic physics characterized by the cosmological constant Λ0. The principle of relativity should further be generalized to the principle of relativity of two universal constants c and l with symmetry of inertial motion of 24 generators.Then there are three kinds of special relativity of Poincaré,de Sitter and anti-de Sitter invariance,respectively.They form a special relativity triple associated with a dual Poincaré invariant degenerated kinematics.The de Sitter special relativity of l=R≈3/Λ presents a new kinematics at cosmic scale and gets ride of relativity's cosmic puzzle.Hua is not only a great mathematician,but also a great thinker, great educator and one of great representatives of modernization in China.
    Explore inertial frame of reference
    . 2010, 29(8):  11-11. 
    Abstract ( 967 )   PDF (429KB) ( 650 )  
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    By discussing on star frame of reference and center-of-mass frame of reference,the conditions that star frame of reference and center-of-mass frame of reference are inertial frames,are indicated.Two doubts about the system of Newton's mechanics are resolved.
    Dirac δ function
    . 2010, 29(8):  16-16. 
    Abstract ( 1208 )   PDF (260KB) ( 571 )  
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    Based on the definition of Dirac-delta function δ(x),no definition at x=0 for δ(x)is explained.The δ(x) possesses a dimension of the reciprocal of x and the physical significance of x operator's eigenfunction.Some ambiguities in quantum mechanics textbooks are clarified.
    Research on double-slit diffraction experiment of C_(60) by a quantum mechanical approach
    . 2010, 29(8):  18-18. 
    Abstract ( 874 )   PDF (363KB) ( 459 )  
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    At the present time,the phenomena of many particles diffraction have been studied in many experiments,and these experiments have been explained by some theoretical works.We study the double-slit diffraction by a quantum mechanical approach.Starting from the Schredinger equation and using Kirchhoff's law,we obtain the diffraction wave functions for the double-slit.We find that when the effects of decoherece is considered in the C60 double-slit diffraction,the calculation results are in accordance with experimental data.
    Study of the critical damping of a nonlinear vibration system with MATLAB
    . 2010, 29(8):  22-22. 
    Abstract ( 809 )   PDF (265KB) ( 1245 )  
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    The nature of the critical damping of a nonlinear vibration system is studied by using MATLAB.The formula for calculating the critical damping and the equation of motion in the critical damping state of the nonlinear vibration system are proposed.The results calculated by the formula and the numerical solution are also compared.
    A new approximate formula and some analyses on constructing for the period of a simple pendulum
    . 2010, 29(8):  25-25. 
    Abstract ( 702 )   PDF (372KB) ( 537 )  
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    Comparing with the series expansion of the exact period,a new approximate fornmla and its modulated form for the period of the simple pendulum are presented.The constructed formula and its modulated form can be applied in the amplitudes of 114° and 136°,respectively,its relative error is less than 1‰.Some analyses on constructing of the period of a simple pendulum are discussed.
    Space electrostatic field of evenly-charged round ring slice
    . 2010, 29(8):  29-29. 
    Abstract ( 728 )   PDF (243KB) ( 554 )  
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    From the formula of electric potential stirred up by a point charge,the space electrostatic field of evenly-charged round ring slice is calculated in terms of the method of superposition principle of electric potential.The relation between the Legendre polynomial and the mother function is discussed.
    The electric potential of equivalent coordinate charged cylindrical shells or planes
    . 2010, 29(8):  31-31. 
    Abstract ( 642 )   PDF (179KB) ( 284 )  
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    The common property of equivalent coordinates is pointed,and the electric potentials of equivalent coordinates charged cylindrical shells or planes is obtained by transforming the potential of charged cylinder.
    Magnetic flux linkage's discussion
    . 2010, 29(8):  33-33. 
    Abstract ( 990 )   PDF (269KB) ( 519 )  
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    This article starts from the contradiction between the two solutions about coefficient of self-inductance in coaxial cable and then introduces the magnetic flux linkage of further analysis.By three examples analyzed the relationship between magnetic flux linkage and magnetic flux,it is shown that magnetic flux linkage and magnetic flux is not only integer relations,but can also be the relationship between the scores of times.So that Ψ in the coefficient of self-inductance L =ΨI is the physical quantity of magnetic field lines in the cross-linked with the current,which should not be used full-called flux or total flux,but rather than the magnetic flux linkage.
    A further investigation on one-dimensional infinite potential well
    . 2010, 29(8):  36-36. 
    Abstract ( 795 )   PDF (272KB) ( 324 )  
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    The dynamic model of one-dimensional potential well with a variable width is presented.It is shown that the particle generally stays in the superposition state and the probabilities for the system at different energies are calculated after resolving the Schrodinger equation,and this probability can be understood as the probability of non-radiative jump up or jump down.
    A new expression of the current in two-level energy system
    . 2010, 29(8):  39-39. 
    Abstract ( 595 )   PDF (167KB) ( 238 )  
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    The current of the ordinary quantum system is discussed in this paper.Then the method is used in the study of a two-level energy system.A new expression of the current in this system is given and a new coefficient is also defined.
    Voltage symmetry method for fast measuring RC time constant of the circuit
    . 2010, 29(8):  41-41. 
    Abstract ( 978 )   PDF (378KB) ( 888 )  
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    The steady-state response of the first-order dynamic circuits is causal periodic signal in the causal periodic square wave signal stimulus.The maximum value of square-wave voltage is u0,and the maximum and minimum values of the capacitor voltage are uCmax and uCmin,they obey a relation: u0-uCmax=uCmin.The waveform of capacitor voltage on the time-axes has special symmetry.By using the steady-state reponse of RC circuit voltage of symmetry,we can export the circuit time constant τ,and the formula for capacitance measurements provides a fast and reliable way.
    The misunderstanding on college physical simulation experiments:Teaching analysis of thermistor temperature characteristics
    . 2010, 29(8):  44-44. 
    Abstract ( 965 )   PDF (334KB) ( 351 )  
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    The college physical simulation experiments is an organic integration of experimental equipment,teaching content,teacher's guidance and learner's thinking.It provides a powerful way of reform for physical experiments.The students use multimedia and computer simulation technology to simulate operation,data processing and analytical thinking.Finally,they can understand and master principles and methods of experiments.But the simulation experiment has also some disadvantages.Through a typical teaching "thermistor temperature characteristics",investigating and analyzing for the simulation experiment,it is obtained some negative effects in the experimental teaching process.Some issues of attention are proposed for the reform of university physics experiments.
    Physical curriculum and textbook for college students of arts
    . 2010, 29(8):  47-47. 
    Abstract ( 697 )   PDF (307KB) ( 370 )  
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    The aim of physical curriculum for college students of arts is to popularize science and improves scientific literacy of citizen. When authors write the textbooks, they must adopt the style which students are really like to accept, choose representative content, help students to learn scientific knowledge and have a full understanding about science and the relationship among science, technology and society.
    The investigation of electromagnetic motor
    . 2010, 29(8):  50-50. 
    Abstract ( 738 )   PDF (463KB) ( 361 )  
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    Attaching a strong light magnet to the head of a steel screw,the screw can hang frorn the terminal of a battery.Completing the circuit by a sliding contact on the magnet causes the screw to rotate.We investigate the parameters determining the angular velocity of the screw theoretically and experimentally and show the theoretical solution,experimental results and the verifications of the phenomena.The conclusion is that the angular velocity of the screw and the pill increases at the beginning of the process and then approaches a constant value.The crucial effects that influence the angular velocity include the induction electromotive force and the moment of resistance that grows with the angular velocity, which is determined by the magnetic flux in the magnet,the current in the circuit,the rotational inertia of the magnetic pill and the moment of resistance.
    Thermal equilibrium in curved space-time
    . 2010, 29(8):  55-55. 
    Abstract ( 764 )   PDF (173KB) ( 329 )  
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    The condition for thermal equilibrium in stationary space-time,which is a special case of curved space-times,is discussed.Using the Planck's theorem of blackbody radiation and principles of general relativity,we conclude two systems that have reached thermal equilibrium through thermal radiation have the same coordinate temperature but generally different proper temperature.
    The limitation propriety of pursuit problem
    . 2010, 29(8):  57-57. 
    Abstract ( 768 )   PDF (294KB) ( 648 )  
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    The initial velocity of three chasers which can meet at rendezvous point is derived by analytical motion method and relative motion method.This point is the Brocard one of triangle and the pursuit curve is the logarithmic spiral curve.
    Rediscovery of Balmer formula
    . 2010, 29(8):  61-61. 
    Abstract ( 702 )   PDF (495KB) ( 433 )  
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    In this paper,we re-obtain the Balmer formula of the hydrogen atom spectrum by means of the data analysis under the guidance of the scientific methodology.This exploring process can be acted as a typical case to promote the creative ability of college students.