College Physics

The Frullani Integrals

WU Chong-shi

College Physics. 2017, 36(4): 1-5. doi:10.16854 /j.cnki.1000-0712.2017.04.001

Abstract ( 2392 )

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The so-called Frullani integrals are discussed in the framework of complex analysis，and extended to cover a wide range of integrands，including many-valued functions and special functions.

Spatial correlations of two identical particles in one-dimensional harmonic oscillator potential

LIU Zhi-wei，SUN Bao-yuan

College Physics. 2017, 36(4): 6-11. doi:10.16854 /j.cnki.1000-0712.2017.04.002

Abstract ( 1410 )

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Inspired by a sample question in the textbook of quantum mechanics，the spatial correlations of two identical particles in the one-dimensional harmonic oscillator potential are discussed，where the exchange symmetry of wave function is assumed to be classical，symmetrical and anti-symmetrical，respectively. It is found that the results for free particles still hold for the one -dimensional harmonic oscillator bound states，namely，when the exchange symmetry is symmetrical，the two particles tend to draw close each other，the probability of two particles approaching each other( r→0) tends to be zero while when anti-symmetrical，which will be useful for understanding the quantum effects induced by the exchange symmetry.

Accurate solutions of free-falling and up-casting problems and discussion on drift and energy

BAO Si-yuan，SHEN Feng，CHEN Liu-feng

College Physics. 2017, 36(4): 12-16. doi:10.16854 /j.cnki.1000-0712.2017.04.003

Abstract ( 1255 )

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Based on the dynamic differential equations of a free-falling particle and an upward casting particle in the non-inertial system，the accurate solutions of the particle’s coordinates are obtained.Then the eastward and westward drift for the two problems are obtained.Expressions of the kinetic energy and potential energy are also obtained. It is demonstrated that the mechanical energy conserves to a constant during the movement. In the numerical examples，we discuss the values of drift with different initial height or initial velocity.

The series solution of oscillation period of a symmetric nonlinear oscillator

WANG Shu-ping

College Physics. 2017, 36(4): 15-16. doi:10.16854 /j.cnki.1000-0712.2017.04.004

Abstract ( 1438 )

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The series solution of oscillation period of a symmetric nonlinear oscillator is derived by using the integral method.Then the vibration period of linear oscillator and oscillating period of the x³ oscillator are obtained and the results obtained are discussed.

Transformation between electromagnetic momentum and mechanical momentum of the pivoting coil of wire in a sensitive galvanometer

PU Tian-shu，JIANG Ruo-shi，YANG Bo，GONG Ji-bin

College Physics. 2017, 36(4): 17-21. doi:10.16854 /j.cnki.1000-0712.2017.04.005

Abstract ( 1176 )

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In terms of the view of electromagnetic field，transformation between electromagnetic momentum and mechanical momentum in three types of the critical，over -and under -damping running of the coil of wire of a sensitive galvanometer is analyzed. It is shown that the electromagnetic momentum is proportional to the angular displacement of the coil of wire so that the electromagnetic momentum the measurement of which generally is difficult，becomes a macroscopic measurable quantity.

Study on uniformity of magnetic field from ellipsoidal coil

JIANG Jun-qin

College Physics. 2017, 36(4): 22-27. doi:10.16854 /j.cnki.1000-0712.2017.04.006

Abstract ( 1198 )

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The uniformity of the magnetic field inside the current carrying ellipsoid coil is studied by using digital image method. Using the outstanding numerical calculation ability and digital drawing function of MATHEMATICA，the three-dimensional diagrams of the magnetic field from a sparse winding ellipsoidal coil are 　　plotted. The ellipsoidal regions corresponding to a variety of uniformity are preformed. The irrationality of the cylindrical uniform area in the existing literature is pointed out. A reliable and convenient method for the research on the electromagnetic field uniformity is provided

Calculation of the magnetic field distribution of an arbitrary quadrilateral electric current

KUANG Xiang-jun

College Physics. 2017, 36(4): 28-31. doi:10.16854 /j.cnki.1000-0712.2017.04.007

Abstract ( 1254 )

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Based on the familiar magnetic field expression of one section current，the x，y，z components of magnetic field for one section current are derived. Then，using this component expression，we get the magnetic field space distribution of the arbitrary quadrilateral electric current and discuss the special cases of rectangular current and square current.

New applications of the experiment data of the Hall effect———extraction of secondary effects and solenoid parameters

NIU Zhong-ming，WANG Hong，ZHANG Zi-yun，WANG Zhang-yin

College Physics. 2017, 36(4): 32-35. doi:10.16854 /j.cnki.1000-0712.2017.04.008

Abstract ( 1681 )

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The experimental data for the internal magnetic field of the current solenoid measured with the Hall effect are employed to estimate the secondary effects of the Hall element，such as the voltage drop due to unequal potential and the additional potential difference due to the Nernst effect and the Righi-Leduc effect，whose influence on results is also discussed in detail. Furthermore，the theoretical formula of magnetic field distribution in the current solenoid is applied to fit the corresponding experimental data using the Origin software. It is found that the basic parameters of the solenoid，including the number of the solenoid turns，length and the mean radius，can be accurately estimated.

Application of electron spin resonance to measurement of Lande-g factor and hyperfine coupling of unpaired electrons in free radicals

YANG Nan，TANG Mian-gang

College Physics. 2017, 36(4): 36-39. doi:10.16854 /j.cnki.1000-0712.2017.04.009

Abstract ( 2232 )

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We use electron spin resonance ( ESR) to study the properties of the unpaired electron in an organic chemical compound 2，2 -diphenyl-1-picrylhydrazyl ( DPPH) ，including its hyperfine coupling with the nucleus and its Zeeman splitting under magnetic field. The Lande-g factor is obtained by measuring the resonance magnetic field and microwave frequency. A magic-T waveguide is applied to increase the signal-to-noise ratio. The Lande-g factor is measured to be 2.033±0.0003，which agrees well with the expectation reference value 2.0036 found in other experiments. This method can be used to study the unpaired electrons in various materials and biosystems. And it also provides a promising method to study the radicals of micro-inductors on chips.

The practical method of introducing the history of physics into College Physics Teaching

NING Chang-chun，CHEN Tian-lu，WANG Ya-ping，HU Hai-bin

College Physics. 2017, 36(4): 40-45. doi:10.16854 /j.cnki.1000-0712.2017.04.010

Abstract ( 1466 )

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According to the specific teaching content and integrating it into the teaching process，we collect the corresponding historical materials，look for typical events in the history of physics and take it as a clue to connect the physics knowledge in teaching content.We carry out some research of the history of physics，whose are three kinds of means of introducing the history of physics into college physics teaching.We think that the practical method is feasible and easies to form a practical method of specification. This paper introduces the practice process and regards introducing the history of physics into college physics teaching as a positive role in cultivating and improving students' scientific literacy and scientific methods.

The automatic counting system of Michelson interference based on smartphone

CUI Da-jun，SONG Yu-hang，XIONG Chang，TANG Fang，CHEN Yan，LI Chao-rong

College Physics. 2017, 36(4): 46-49. doi:10.16854 /j.cnki.1000-0712.2017.04.011

Abstract ( 1262 )

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Counting the number of interference fringes has always been a headache in the Michelson interferometer experiment for measuring the wavelength of He-Ne laser.In this paper，we introduce the automatic counting software system based on smartphone.The software comes with a smartphone camera to capture the interference fringe image.We use the Fourier transform filter analysis to calculate the number of fringe throughout automatically.The system is simple to 　　operate and has a counting accuracy of up to 0.5 fringe，which greatly improves the measurement accuracy.With the popularity of smartphone applications，the system has broad application prospects.

Waste water treatment system based on Kelvin water drop

SU Xiao-huang，ZHENG Ji-wen，SHI Zhan，ZHONG Ying-yi，

College Physics. 2017, 36(4): 50-56. doi:10.16854 /j.cnki.1000-0712.2017.04.012

Abstract ( 1479 )

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Based on the principle of the Kelvin water drop，the idea of applying the high-voltage electrostatic field generated by the water drop to the sewage treatment， is presented in the research.In order to improve the system’s efficiency of oxidization and sterilization，the factors influencing the electrification effect are discussed.We optimize structure of the sewage treatment system according to the experimental data.The experimental result shows that the system is able to oxidize methylene-blue liquid effectively，reflect its capacity for oxidization and sterilization， without any external energy sources，demonstrat its superiority of environmental protection and no secondary pollution.

Research on the optimization of Kelvin dripping-water charge collector

YUAN Wei-li，CHEN Xing-mei，SU Yan-xia，HUANG Sen，GUO Chao-ming，LI Dong-yu

College Physics. 2017, 36(4): 57-60. doi:10.16854 /j.cnki.1000-0712.2017.04.013

Abstract ( 1472 )

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Kelvin dripping - water charge collector has attracted widespread attention as its potential applications.Its charge collector effect is affected by many factors，especially by the humidity of the environment. Thus it is a research hotspot on improving the charge collector effect in high humid environment. The traditional 　　Kelvin dripping-water charge collector is improved by optimizing its production materials，induction coil turns， dropping velocity，distance from dribbling nozzle to induction coil，dripping distance，etc.Experimental results show that the starting time of the improved Kelvin dripping - water charge collector is shortened significantly，and a relatively remarkable high electrostatic voltage is obtained in a high humid atmosphere up to 85%.

The layer exploring-progressions tests diagnosed and applied in the teaching of electromagnetics

LU Rong-de，CHENG Fu-zhen

College Physics. 2017, 36(4): 61-65. doi:10.16854 /j.cnki.1000-0712.2017.04.014

Abstract ( 1258 )

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The layer exploring - progressions tests is diagnosed and applied in the teaching practice of electromagnetics. In the case of teaching method，three different types of exploring-progressions tests are applied in diagnosis or study of students' misconceptions process so as to effectively product teaching idea of taste thought， layer-progressions，situation-inquiry during teaching practice.

College Physics. 2017, 36(4): 66.

Abstract ( 607 )

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