College Physics

History of making the first laser-50^th anniversary of inventing the first laser

. 2010, 29(1): 2-2.

Abstract ( 851 )

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The course of events of making a laser, from Einstein＇s concept of stimulated emission to Maiman＇s first laser, were reviewed based on the published reports.

The statistical law of the nearly independent particle system （4） -Grand canonical distribution function

. 2010, 29(1): 8-8.

Abstract ( 1019 )

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Starting from the Gibbs ensemble theory, the grand canonical distribution function, chemical potential, number fluctuation and energy fluctuation formula of the nearly independent particle system that consists of any number of particles are derived. Based on the hard sphere model, we have performed the computer simulation for the grand canonical distribution function of 2D and 3D mechanic systems. Our results are in agreement with the theory.

Medium loss and electromagnetic energy

. 2010, 29(1): 13-13.

Abstract ( 1036 )

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Based on the energy-flux density formula, we deduce the Poynting theorem in the presence of simple harmonic field and loss medium. Combined with the law of conservation energy, we get the power density formula of polarization loss, magnetization loss and Joule loss and electromagnetic energy density formula in loss medium. Finally we get the average value formula of above-mentioned quantity

Dynamic simulation of potential barrier penetration based on the finite difference time omain method and Monte Carlo method

. 2010, 29(1): 16-16.

Abstract ( 864 )

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Both the wave function and the probability density of an electron wave during the process of barrier penetration are calculated based on the finite difference time domain method. Using the Monte Carlo method, we propose the probability density to be described by the denseness of random point and simulate dynamic process of potential barrier penetration.

Thought induced by a question of the variety of rotation of the earth

. 2010, 29(1): 19-19.

Abstract ( 751 )

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The variety of kinetic energy of the earth is investigated for a car going northward. The dynamical reason for this problem is discussed.

Discussion on the boundary conditions of tangential components of electromagnetic field

. 2010, 29(1): 21-21.

Abstract ( 741 )

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In the current texts of electrodynamics and electromagnetic field theory, there were some errors and various methods for deducing the relationship of tangential components of the electromagnetic fields on either side of a surface between different media. Two kinds of methods are introduced to deduce the relationship of tangential components of the electromagnetic fields on either side of a surface between different media and the corresponding questions are discussed.

Study of the electric field for a linear group of infinite linear charged by the complex potential method

. 2010, 29(1): 23-23.

Abstract ( 1643 )

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The complex potential of an infinite linear charged line is obtained firstly. Then a series of infinite linear charged lines are arranged parallel to a line or parallel to ring, the complex potential and the electric field distribution of the charged line group are studied, the equations of the electric field lines and the equipotential lines are also discussed.

Two-dimensional Green function of the first kind calculated by conformal mapping

. 2010, 29(1): 26-26.

Abstract ( 877 )

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Starting from the Riemann theorem and combining with the electric potential formula of a linear charged inside a unit circle, we perform a two-dlmensional Green function of the first kind by conformal mapping.

Discussion on equivalent inductance and current distribution on parallel

. 2010, 29(1): 31-31.

Abstract ( 1053 )

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The article firstly discusses the equivalent inductance of parallel coils, and shows the relation of the parallel coil＇ s equivalent inductance with both their coupling coefficient and their self-inductance. Second, it particular analyzes the current distribution in parallel coils. It is shown that when the coupling coefficient is rather large, the mutual-inductance is greater than one of their self-inductance, at the instant which circuit is connected, the direction of the currents in two coils would turn out to be in the opposite way, and the value of impulse current would be larger than the current of the steady state. At last, the experiments and tests are proved by the theoretical analysis.

Discussion on independence of the boundary value relations of the inter surface between ideal conductor and insulation material

. 2010, 29(1): 34-34.

Abstract ( 1265 )

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It is proved that there are only two boundary value relations of the inter surface between ideal conductor and insulation material. We present an aherative method to get en×H=at from en·D=σf

An approach to solve the exact energy spectrums of three-dimensional coupled harmonic oscillators

. 2010, 29(1): 36-36.

Abstract ( 816 )

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Based on the rotation transformation in the phase space and the technique of integration within an ordered product of operators, the coherent state representations of the rotation operator in quantum phase space, the Fourier transform operator and the parity operator are derived. Then the three-mode rotation operator is introduced.By the three-mode rotation operator, the Hamilton of the three-dimensional coordinate-momentum coupled harmonic oscillators is simply decoupled. Then its exact energy spectrums and eigenstates are obtained.

Application of Snake model in the Zeeman effect experiment

. 2010, 29(1): 39-39.

Abstract ( 872 )

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The Zeeman effect experiment is improved by using the CCD image capture system. The major influential factor of experimental error is the method of digital image processing. The Snake model is applied in the processing to improve the variability and the accuracy of experiment. And the original nonlinear fitting is applied to measure the error assessment.

Retrieving the weak signals of photoacoustic spectroscopy precisely by wavelet analysis and first-derivative method

. 2010, 29(1): 42-42.

Abstract ( 745 )

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Based on wavelet transform and first-derivative photoacoustic spectroscopy（PAS）, a new analytical method for PAS is presented. An experiment setup is specially designed to get the first-derivative spectrum,thus the sensitivity of PAS analysis is improved. In order to increase the accuracy of measurement,the wavelet transform is introduced to decompose the PAS signal into localized detail signals according to the frequency,noise and PAS signals can be discriminated by the difference of frequency,and the position of PAS peaks in time axis and the original linearity are not changed,hence the useful information can be obtained by this decomposed result. Due to the wave- let method and derivative PAS method,three weak absorption peaks which hidden in PAS of Xenon lamp output are precisely retrieved,whose wavelengths are 669.7 nm,753.4 nm and 776.5 nm, respectively. This new analytical method,which takes advantage of the virtues of physics method and software technique, can be used to improve the sensitivity and accuracy of PAS analysis effectively, and it is expected to be a useful analysis tool in biology medical and chemistry analysis.

Study on causes of freezing level height increasing in China by the adiabatic atmospheric model

. 2010, 29(1): 46-46.

Abstract ( 913 )

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It was found that the freezing level height had an increase of about 200 meters since 1970s in China. In this paper, the potential causes are discussed by using the adiabatic atmospheric model

Spectroscopic terms of equivalent electrons derived within the Mathematica

. 2010, 29(1): 48-48.

Abstract ( 713 )

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A new simple program is complied with combinatorial mathematics method and Mathematica software for deriving spectroscopic terms of equivalent electrons. Spectroscopic terms for f^n（n = 1 -14） and g^n（n = 1 -18） are obtained systematically.

Key points for discussing course of fundamental physics facing engineering students

. 2010, 29(1): 52-52.

Abstract ( 679 )

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Discussing course of exercises is an important segment of ＂fundamental physics＂ course facing engineering students in scientific pattern. This paper illustrates and analyzes four key points to carry out the discussing course.

Teaching research of college physics in the independent school

. 2010, 29(1): 54-54.

Abstract ( 815 )

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The main problems and difficulties of teaching college physics in the independent school are analyzed. Many teaching measures are put forward to improve the teaching quality of college physics, which includes strengthening the concept of infinitesimal and physical model, paying attention to the establishing of physical image and the guiding of the physics history education and studying method, combining theory with practice, and so on.

Experimental design of RLED multi-parameter test system

. 2010, 29(1): 57-57.

Abstract ( 872 )

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An experimental system for measuring properties of the infrared light-emitting diode （RLED） is designed. The relationships of current-voltage, current-light intensity, spectral distribution, angular distribution of luminous intensity and duty-luminous intensity are investigated. As low-cost, high sensitivity and easy operation, the system can be used for physics experiment teaching.

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