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Table of Content

    20 July 2014 Volume 33 Issue 7
      
    著者文摘
    Several questions arising from a problem in the physics competition
    . 2014, 33(7):  1-1. 
    Abstract ( 951 )   PDF (322KB) ( 580 )  
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    By solving a problem from the physics competition in the context of special relativity,we discuss several questions which are related to the Doppler effect, rest masses of the atom in different states, Lorentz transformation.
    Research on local vibration of a linear monatomic chain with a terminal impurity atom by data induction method
    . 2014, 33(7):  4-4. 
    Abstract ( 684 )   PDF (419KB) ( 335 )  
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    The local vitration mode of a linear monatomic chain with a terminal impurity atom is investigated by using numerical value calculation and data induction method.
    The fractional dimension of a sandwich quantum well
    . 2014, 33(7):  8-8. 
    Abstract ( 666 )   PDF (248KB) ( 529 )  
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    The dimension for infinite potential and finite potential quantum well is discussed. The dimension of infinite potential well monotonically decreases from 3 to 2 with the decrease of well width. In finite potential well, the dimension of quantum well tends to 3 when the well width is larger or goes to zero. As the well width decreases, the dimensions of the quantum well decreases firstly and then increase, and have their minima.
    Does the moon exist only when someone is looking at it?
    . 2014, 33(7):  11-11. 
    Abstract ( 942 )   PDF (514KB) ( 370 )  
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    The wave-particle duality of micro particles could lead to many effects that are hard to be understood by daily experiences, thus beginners have many difficulties and easily fall into confusion in learning the basic concepts of the quantum physics. The quantum effects are too abstract to be understood for a beginner because the electrons and atoms in microphysics can not be seen directly and hard to imagine. In teaching atomic physics and quantum physics, one can magnify the quantum effects to the macro world to show the strong conflicts between the peculiar quantum effects and people' s daily experiences. In this paper some examples are introduced to show this technique, which will be helpful in understanding the basic concepts. The quantum effects are magnified to the macro objects by artificially change the Planck constant,and therefore lead to some interesting results.
    A comparison between the discrete and integral models of a solenoid
    . 2014, 33(7):  15-15. 
    Abstract ( 566 )   PDF (255KB) ( 500 )  
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    The magnetic field on the symmetrical axis of a solenoid is calculated by using the discrete method and compared with that of the integral method. The applicable conditions of the integral method are given.
    Calculation of the capacitance for a non-parallel plate capacitor
    . 2014, 33(7):  17-17. 
    Abstract ( 997 )   PDF (317KB) ( 668 )  
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    Previously,most of the literatures have ignored the external electric field of capacitor in the calculation of non -parallel plate capacitor and capacitor electric field. In the present work, we investigate the external electric field of capacitor and apply three methods to get more accurate results with correction term.
    Analysis of the experimental conditions for measuring the coefficient of viscosity by falling ball method
    . 2014, 33(7):  20-20. 
    Abstract ( 2595 )   PDF (379KB) ( 2916 )  
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    Starting from the established condition of Stokes' law, we discuss the correction term of Stokes equaton. The Reynolds number correction term relative error on the viscous drag effects is studied and the falling ball diameter, sticky lag coefficient on Reynolds number effects are also analyzed. It is concluded that the measurement error is controlled within the allowable error range, it must satisfy the five established conditions of Stokes' law in the experiments.
    Experimental study of first-order magnetic buoyancy for ferrofiuid
    . 2014, 33(7):  24-24. 
    Abstract ( 813 )   PDF (828KB) ( 575 )  
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    The formula for first-order magnetic buoyancy is derived based on the Bernoulli's equation of ferrofluid. The distribution of first-order magnetic buoyancy is studied at various axes by the experimental method in order to understand the basic reason of first-order magnetic buoyancy. The first-order magnetic buoyancy is influenced by magnetic field intensity, magnetic field gradient, saturation magnetization and susceptibility of ferrofluid. With decreasing magnetic field intensity and magnetic field gradient along z direction, the first-order magnetic buoyancy grows smaller gradually and goes to zero at the end; therefore suspending power of ferrofluid weakens. Saturation magnetization and susceptibility of MFP-1 ferrofluid are bigger than MFP-2 ferrofluid and first-order magnetic buoyancy of MFP-1 ferrofluid is bigger. When the current is 3.00A, glass, aluminum, brass, red copper and lead bails have been suspended and Rosensweig peaks appeared in the MFP-1 ferrofluid, but glass, aluminum and brass balls were only suspended in the MFP-2 ferrofluid. The distributions of magnetic field intensity and mag- netic field gradient are different along r direction at various heights. Magnetic field gradient goes to zero gradually with increasing the height and is the primary affecting factor for first-order magnetic buoyancy. Nonmagnetic balls are moved to the sidewall of glass beaker where the first-order magnetic buoyancy is smaller.
    Approach of generalized equivalent source method to controlled source circuit
    . 2014, 33(7):  30-30. 
    Abstract ( 808 )   PDF (382KB) ( 811 )  
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    A method for solving controlled power source circuits in terms of the generalized equivalent power theorem is proposed. The control variable of the controlled source is regarded as the port current or voltage by using the generalized Thevenin-Norton theorem and constructing a solving model to the multi-port equivalent circuit. The port current or voltage of the original circuit out is calculated, thereby the circuit solving process is simplified. We present a detailed solution which procedures a numerical example to verify the correctness and practicality and is suitable for containing multiple controlled source circuits solving.
    History review of internal conference on physics experiment teaching in university --Talk from "A congratulatory letter of professor YU Fu-chun"
    . 2014, 33(7):  35-35. 
    Abstract ( 631 )   PDF (1490KB) ( 516 )  
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    Based on the investigation on references about opening of the domestic conference on physics experiment teaching in university, the development career and related substance of all previous seminar mentioned above ( including time, place, unit undertook, type of meeting and so on) are introduced briefly in this paper, and two of them are given a further presentation in detail.
    The electric and magnetic fields on the axis of charged regular polygon plate
    . 2014, 33(7):  42-42. 
    Abstract ( 877 )   PDF (234KB) ( 408 )  
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    The analytical expression of electric fields on the axis of uniform charged regular polygon plate is given. When the plate spin, the analytical expression of magnetic field on the symmetry axis is also given.
    Squared form factors of atoms and molecules calculated by approximation theory
    . 2014, 33(7):  45-45. 
    Abstract ( 1129 )   PDF (276KB) ( 341 )  
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    We apply the approximation theory to calculate the squared form factors of atoms and molecules in ground state. Then as an example the squared form factors of atomic hydrogen is calculated and compared with the accurate one determined by analytical solution. Then the different approximation methods such as Hatree-Fock and density functional theory as well as different basis sets are tested. The present method can be extended to calculate the squared form factors in the ground states of other atoms and molecules whose wave functions cannot be prepared analytically.
    Research on two-dimensional gravitational field simulated by isotropic elastic membrane
    . 2014, 33(7):  48-48. 
    Abstract ( 981 )   PDF (925KB) ( 492 )  
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    The deformation of an isotropic elastic membrane that is produced by external force loaded upon the cenlrum is studied through theoretical analysis, numerical simulation and experiments. The results show that the in- fluence of the deformed membrane to an object moving on it can be equivalent to a" two-dimensional gravitational field". In addition, the motion of a mass point put into this" gravitational field"is investigated, and the difference from three-dimensional gravitational field is discussed.
    Optimizing the dynamic measurement of thermal conductivity and error analysis
    . 2014, 33(7):  52-52. 
    Abstract ( 964 )   PDF (356KB) ( 330 )  
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    A new method to calculate thermal conductivity employing Fourier transform is proposed, largely improving the original method in this experiment. The stability and error of the new method are discussed. Causes of error including the finite length of the sample, machining error are analyzed. Error analysis shows that if machining error is lowered, the total error can be kept below 5%. And suggestions to improve the experimental equipment are proposed
    Feature and revelation of 《Art Physics --Physics in Our Lives》
    . 2014, 33(7):  56-56. 
    Abstract ( 912 )   PDF (682KB) ( 1118 )  
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    In this paper, we give a full analysis and evaluation to the teaching material 《Art Physics--Physics in Our Lives》. Through a detail study of the characteristics of this book, we promote three advices : pay attention to the humanities teaching; concepts are much important; have more interesting illustrations.