Table of Content

20 December 2016 Volume 35 Issue 12

  

Numerical simulation of the Duffet - Boissonade equations in pattern dynamics

PENG Fang-lin， JU Xiao-lin，LIU Chang

College Physics. 2016, 35(12):  1-6.  doi:10.16854/j.cnki.1000-0712.2016.0171

Abstract ( 2019 )   PDF (5358KB) ( 1574 )  

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The one - and two - dimensional numerical simulations of Duffet - Boissonade reaction-diffusion equations in pattern dynamics are performed. Setting up four kinds of different initial conditions and selecting the parameters in the equation according to Turing bifurcation condition，the hexagon pattern and fringe pattern obtained from the simulation are very similar to the experimental results.

A discussion about the acceleration strange point in some questions of soft and thin cords' movement

LU Jun-ling，QIN Lian-hua，REN Nai-jing

College Physics. 2016, 35(12):  7-12.  doi:10.16854/j.cnki.1000-0712.2016.0172

Abstract ( 1549 )   PDF (805KB) ( 1718 )  

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Questions involving soft and thin cords’movement are a kind of model of college physics. A soft  and thin cord is an ideal model for the actual one，which makes the acceleration be infinite at some point of the soft and thin cord. This is the acceleration strange point. If the acceleration strange point is neglected，some mistakes may arise. A discussion is given here by an example of a soft and thin cord.

A study of the equivalent resistance of an n - step network with tripod structure

TAN Zhi-zhong，LU Jian-long

College Physics. 2016, 35(12):  13-18.  doi:10.16854/j.cnki.1000-0712.2016.0173

Abstract ( 1196 )   PDF (579KB) ( 472 )  

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We study the equivalent resistance of an n - step network with tripod structure，which is a profound problem，has not been resolved before. The network model contains seven arbitrary parameters which make the network contain a number of different types. First of all，we establish a nonlinear difference equation by means of simplifying a complex graphics into a simple equivalent model; next，we construct the method of equivalent transformation to obtain the general solution of the nonlinear difference equation. Finally，we create a new concept of negative resistance for the needs of the equivalent conversion，and obtain two general resistance formulae of an n - step network with tripod structure. We compare several results by making use of a number of specific examples in 　　the special conditions. Our method and the results are suitable for the research of complex impedance network as well.

The fundamental properties of electron relativistic radial wave function

LIU Xiao-bin，SHI Ying-long，XING Yong-zhong，LU Fei-ping

College Physics. 2016, 35(12):  19-22.  doi:10.16854/j.cnki.1000-0712.2016.0174

Abstract ( 1898 )   PDF (577KB) ( 1423 )  

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The fundamental properties of electron relativistic radial wave functions have been studied theoretically based on the relativistic average self - consistent field. Usually，the small - component of relativistic radial wave functions is several orders of magnitudes less than the large - component，and is not generally synchronous with the large - component，so the radial probability density of electron has no exact zeros. The number of nodes for bound electron large - or small - component is n - l - 1，so that the number of antinodes is n - l，but the number of nodes and antinodes for free electron just turn to infinite. The radial wave functions are extremely sensitive to the relativistic effects，the amplitude of small - component increases with increasing relativistic effects，as well as the oscillating intensity of large，small - component for free electron.

The solution of spatial derivatives of unit vectors using differential geometry method

LUO Hong-chao，JU Li-ping

College Physics. 2016, 35(12):  23-25.  doi:10.16854/j.cnki.1000-0712.2016.0175

Abstract ( 2774 )   PDF (562KB) ( 2014 )  

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By using the differential geometry，the vector limit and the relationship of various coordinate systems，we deduce the spatial derivatives of unit vectors in common curvilinear coordinates. This derivation method is simple and intuitive，which is easy to understand and apply in physics teaching and practice.

The application of infrasound measurement to physics experiment teaching

DONG Cai-xia，HE Yan-lan，YANG Wei-xin，ZHAO Yun，PENG Gang

College Physics. 2016, 35(12):  26-29.  doi:10.16854/j.cnki.1000-0712.2016.0176

Abstract ( 1086 )   PDF (828KB) ( 667 )  

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In college physics experiment，experiment on sound is less，more common is the use of the characteristics of ultrasonic wave to measure the sound velocity，and the study of infrasound source and the acoustic field distribution are rare. The“separation of push-pull flow modulation”infrasound generator we designed can do experiments of infrasound source and relevant acoustic field measurement，which can make students understand the characteristics of infrasound，the mechanism of energy conversion of the air-modulated infrasound source，and the basic method of sound field measurement. Using MATLAB to analyze the data measured in experiments and COMSOL to do sound field numerical simulation，can make the students know the distribution of sound field and 　　directivity of the sound source. Thus which can broaden the students’knowledge，improve the students’ability of experiment and data processing and analysis.

Quantitative study of dampening effect on the nonmagnetic revolving metal plate

LIU Yu-long，YU Xiao-ming

College Physics. 2016, 35(12):  30-33.  doi:10.16854/j.cnki.1000-0712.2016.0177

Abstract ( 1304 )   PDF (448KB) ( 923 )  

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The regression equation of angular velocity of a nonmagnetic revolving metal plate is deduced by using the Faraday’s law of induction. Then，both frictional damping coefficient and electromagnetic damping coefficient are defined and measured. Lastly，the relationship between the electromagnetic damping coefficient and the value of exciting current is analyzed.

Historical development of physics education in China starting form scartch to international level( upper)

Zhao Kai-hua

College Physics. 2016, 35(12):  34-41.  doi:10.16854/j.cnki.1000-0712.2016.0178

Abstract ( 1431 )   PDF (260KB) ( 963 )  

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This article is divided into three chapters. The first chapter describes the historical process in the Qing Dynasty from the Westernization Movement，through the Sino-Japanese War in 1894，the Constitutional Reform in 1898，the Boxers Riot and the Incident in 1900，the abolishment of Imperial Examinations，to the establishment of new schools. At this stage physics education in China was in the bud.

Historical development of physics education in China starting form scartch to international level( middle)

Zhao Kai-hua

College Physics. 2016, 35(12):  42-47.  doi:10.16854/j.cnki.1000-0712.2016.0179

Abstract ( 1005 )   PDF (207KB) ( 640 )  

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The middle chapter is devoted to the historical development of physics education from the Revolution of 1911 to the Republic of China before the outbreak of the War of Resistance against Japan. During that time，a group of outstanding universities were established. Physics education began to take shape and had great development. A large number of graduates went abroad to study and became leaders in the physic community of China after they came back. A group of physicists devote themselves to the career of nation rescue by science and industry. They made great efforts and even sacrificed.

historical development of physics education in China starting from 　　scratch to internatioal level( last)

Zhao Kai-hua

College Physics. 2016, 35(12):  48-53.  doi:10.16854/j.cnki.1000-0712.2016.0180

Abstract ( 1066 )   PDF (215KB) ( 915 )  

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The last chapter concludes the article with the description of physics education during the War against Japan and in the period of demobilization after the war. Much distress regenerates the nation. The extreme hardship during the war inspired National Southwest Associated University，which was a wonder in the history of education. From the philosophy to the institutional system of education， from the curriculum to the pedagogical materials and experimental instruments，modern education of China was basically borrowed from the West，By the end of 1940s a group of home-grown scientists of high level appeared.

Faraday's research on liquid surface wave

LI Guo-feng

College Physics. 2016, 35(12):  54-56.  doi:10.16854/j.cnki.1000-0712.2016.0181

Abstract ( 1616 )   PDF (189KB) ( 941 )  

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The course of Faraday for turned from Chladni figures to liquid surface wave from is introduced，and the experiment research on liquid surface wave for Faraday to do is reviewed. Faraday's spirit of the strong curiosity and correct discrimination authoritative scholars point of view，as well as Faraday's characteristics of flexible thinking excellent experimental skills are analyzed.

Max Born’s special summary on his scientific career

HOU Yu-de，TAO Pei-pei

College Physics. 2016, 35(12):  57-61.  doi:10.16854/j.cnki.1000-0712.2016.0182

Abstract ( 1419 )   PDF (719KB) ( 887 )  

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How many collaborators did Born have in all his life? And who were they? How many Ph. D. students did Born have supervised in all his life? And who were they? Born had been the fellows and members of many country and their scientific societies，what were they? How many main Medals or Prize Born had get? What were they? Which was the most important contribution，Born thought， in his work?. . . We could not find the exact and overall answers of these questions in Born's autobiography or his biography by other people. But we can find all these answers in the Confidential Personal Records of Fellows of the Royal Society，which wrote by Born himself. Based on the file and other books， the paper sums the scientific career of Max Born from eleven aspects.