College Physics

Force operator in one-dimentional infinite square-well potential

LIU Fei, ZHAO Lu, HU Lei

College Physics. 2019, 38(1): 1. doi:10.16854 /j.cnki.1000-0712.170621

Abstract ( 2406 )

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Calculation of the mean force applied on the wall of one-dimensional infinite square-well potential

is an exercise that is frequently met in quantum mechanics textbooks. Recently，it also attracts interesting in the

study of quantum nonequilibrium processes. In this paper，a force operator is proposed and is utilized to re-obtain

previous result. Its correctness is as well proved in the case of one wall moving at constant velocity. The advantage

of the operator is that a process of taking limit does not need，where one has to calculate the mean force for a finite

square-well potential first and to take the potential-depth be infinite later. The computations show that，in quantum

regime using a time-dependent canonical transformation to define a force operator is neither correct nor essential.

The complex interplolation approach to analysis of the planar motion of rigid bodies

ZHANG Xin-hua

College Physics. 2019, 38(1): 5. doi:10.16854 /j.cnki.1000-0712.180081

Abstract ( 1673 )

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In this paper，the complex interplolation method ( CIM) is proposed for analysis of the planar motion

of rigid bodies. Based on the known kinematical information ( displacement，velocity and acceleration) of two

points in a rigid body，the displacement，velocity and acceleration of any other point in the rigid body can be determined

by the CIM.The present method provides a unified way to the analyses of displacement，velocity and acceleration

of the planar motion of a rigid body，on the other hand，it is easy to implement in the computer.

Analysis of the truncation error of series solutions for vibrating string problem

HAN She-jiao, HE Jia-qi

College Physics. 2019, 38(1): 8. doi:10.16854 /j.cnki.1000-0712.180241

Abstract ( 2062 )

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Based on three different forms of the series solutions of the vibrating string equation under the definite

condition，the truncation error of the series solutions is discussed in two different conditions，ignoring or not ignoring

the independent variables. When the independent variables，by estimating the general truncation error，defining

the Gibbs-like phenomenon is considered，we obtain the estimation of the maximum value of the truncation error.

Application of Gegenbauer polynomials in some physical problems

LIN Qiong-gui

College Physics. 2019, 38(1): 13. doi:10.16854 /j.cnki.1000-0712.180325

Abstract ( 1506 )

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Some applications of the Gegenbauer polynomials in physical problems are presented. The problems

discussed include heat conduction problem and Schrdinger equation in a spherical clove domain，and the effect of

an Aharonov-Bohm vector potential on the energy levels of bound states in a central potential.

Derivation and application of variation rate of the magnetic flux in a loop with general motion

LUO Chao-yi

College Physics. 2019, 38(1): 17. doi:10.16854 /j.cnki.1000-0712.180177

Abstract ( 2421 )

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This paper deduces the variation rate of the magnetic flux in a rigid loop with translational and rotational motion. It is proved that motional electromotive force obtained by the law of electromagnetic induction is equal to that obtained by the Lorentz force. The formula is applied to analyze magnetic force and torque on current-carrying loop and induced current. The result has provided theoretical foundation for the study of basic problems about electromagnetism.

Interference field analysis of two partially polarized lights

DING Wen-ge, LI Wen-bo

College Physics. 2019, 38(1): 20. doi:10.16854 /j.cnki.1000-0712.180364

Abstract ( 1699 )

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Based on the superposition and interference theory of waves，when an extreme value of light intensity

is parallel，the related formulas of the intensity distribution of interference field and the contrast degree of the interference

fringe by two partially polarized lights are obtained. The formulas can be applied to various interference

processes in which natural light，linear polarized light and partial polarized light composed of them participate. On

　　the basis of these，the interference field of different polarization state light such as line polarized light and line polarized

　　light，natural light and natural light，line polarized light and natural light are analyzed in detail. The specific

　　expressions of light intensity distribution of interference field and contrast degree of the interference fringes are given.

　　The conclusions are of great significance to recognition of interference field of the aforementioned polarization

　　states and to improvement of the contrast degree of interference fringes of the corresponding interference field in the

　　interferometer.

Uncertainty in uncertainty of quantum uncertainty relation

LI Jun-gang, HU Hai-yun

College Physics. 2019, 38(1): 25. doi:10.16854 /j.cnki.1000-0712.180278

Abstract ( 1898 )

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The uncertainty relationship is an important part of quantum physics theory. It is not easy to explain

this part well in the college physics course in a limited period of time. Firstly，some problems and their solutions of

the uncertainty relation encountered in the lecture are introduced. Then several introductions of the uncertainty relationship

are given in order to deepen the understanding of the uncertainty relationship from different perspectives.

Inversion algorithm for fermion matrix with multi-different mass terms

WU Liang-kai, GU Xin, LIU Kun, FENG Long-hai

College Physics. 2019, 38(1): 29. doi:10.16854 /j.cnki.1000-0712.180181

Abstract ( 1567 )

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In the simulation of lattice gauge theory，RHMC algorithm is an accurate algorithm which can be

used to any number of fermions. Its central idea is to expand the fermion determinant into rational functions，the implementation

of this algorithm results in a lot of matrix inversion of fermion matrix，and brings about numerous time

and resources consumption. Therefore，its use is limited. This paper uses the shifted polynomial to obtain an approach

　　to solve this problem for the conjugate gradient method. This approach can be applied into RHMC algorithm.

Propagator of the driven oscillator with time-dependent mass and frequency

XIA Xiao-jian, CHEN Wen-zhi

College Physics. 2019, 38(1): 32. doi:10.16854 /j.cnki.1000-0712.180024

Abstract ( 1519 )

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Many physical systems can be described by oscillator with time-dependent mass and frequency. Investigation

and solution of time-dependent system are very important in quantum field as well as in quantum optics.

We use SU( 1，1) Lie-algebraic technique to investigate the harmonic oscillator with time-dependent mass and frequency

and obtain the time evolution operator by solving Riccati equation. Than the formula of the system is derived

in phase space. Finally，we obtain the propagator of oscillator of the free particle，driven by gravity，period mass

　　and damped system.

An alternative approach to test the acceleration of gravity by using sensors in smartphone

RAO Di, CHENG Min-xi

College Physics. 2019, 38(1): 37. doi:10.16854 /j.cnki.1000-0712.180232

Abstract ( 5051 )

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One experiment is designed by using the sensors in smartphone including pressure sensor，temperature

sensor. The acceleration of gravity is obtained through linear fitting by measuring the relationship between relative

altitude and air pressure. This new method needs not additional equipment and the experimental procedure is

easy to do.

Mechanical properties of Vicryl suture measured by tensile method

LIU Xiao-li, YUAN Xiao-yan, NIU Xiao-dong

College Physics. 2019, 38(1): 39. doi:10.16854 /j.cnki.1000-0712.180422

Abstract ( 1897 )

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On the basis of FD-YC-II Young’s modulus tester，JCD3 microscope is employed to instead JC10

microscope，and then by adding and reducing weight to Vicryl suture at room temperature，the axial elongation is

measured by stretching method. The stress - strain curve，tensile strength 518. 824 MPa，elongation at break

14.087%，yield strength 76.8 MPa，yield strain 1.57% and Young's modulus 81.505 MPa have been measured.

The stress-strain hysteresis loop of Vicryl suture is also obtained.

Research on student-centered teaching reform of the elementary physics course

LU Hui, ZHANG Meng, LUO Duan-bin, WANG Rong, FANG Yi,

College Physics. 2019, 38(1): 43. doi:10.16854 /j.cnki.1000-0712.180320

Abstract ( 1991 )

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On the basis of the teaching reform exploration and practice of the public basic course，university

physics，and the professional basic course，optics， this paper expounds that the teaching process is optimized and the

teaching mode is reformed under " student-centered" idea and according to the characteristics of the elementary

physics course. With the combination of the overall guidance and the individual guidance and the transform of classroom

teaching from the closed to the open，and so on， the students' full development and personality development are

　　promoted and the research learning model is formed.

Discussion and practice of college physics information-based teaching

LU Shu-hua, TIAN Fang, WANG Li-hui

College Physics. 2019, 38(1): 47. doi:10.16854 /j.cnki.1000-0712.180215

Abstract ( 1618 )

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College physics is a compulsory basic course for most majors in science and engineering. It plays an

important role for students in their natural science knowledge system construction，the learning of professional

courses，and the cultivation of scientific quality. The discussion and practice of college physics information-based

teaching mode and content are performed based on the authors experience. Using the“Internet + curriculum”idea，

　　traditional and modern integrated teaching modes are constructed through the use of intelligent teaching tools such

　　as online teaching platform，WeChat，and rain classroom，which optimize the traditional teaching methods and

　　highlighted multisource，three-dimensional and information-based teaching methods. The integration of teaching

　　content and public security technology disciplines are enhanced，which make a professional basic platform and

　　highlight its pertinence and application. It is expected to provide some reference for college physics teaching of

　　similar majors.

Vibration modes and shape threshold of Leidenfrost floating droplets

ZHANG Yu-bo, SUN Wen-jie, JIANG Ying-hua, DONG Rui-ge,

College Physics. 2019, 38(1): 53. doi:10.16854 /j.cnki.1000-0712.180198

Abstract ( 1662 )

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On the basis of the research on vibration mode of floating droplets，this paper discusses Leidenfrost

effect and the threshold radius of Leidenfrost stars in various stages. It is found that the vibration modes of floating

droplets correspond to radius range. Both the theoretical and experimental results indicate that floating droplets are

divided into three main modes by two thresholds. When the radius is smaller than the lower boundary of threshold，

droplets are contracted to a spheroidal one because of surface tension; on condition that the radius is larger than the

outer boundary of threshold， the pressure difference between the inner and external part of droplets is negative，

which destroys the original vibration of droplets and forms a bubble at the bottom of droplets. In this case that floating

droplets between two modes， forms Leidenfrost stars and the modes of stars is linearly enlarged with the increase

of radius. In contrast， the modes of stars decrease with evaporating.

Production and application of Tesla coil demonstrator

GONG Jun-long, LU Rong-de

College Physics. 2019, 38(1): 58. doi:10.16854 /j.cnki.1000-0712.180274

Abstract ( 1952 )

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This paper briefly introduces Tesla coil and its working principle，and a simple and safe demonstrator

for Tesla coil has been made. Using this demonstrator，a series of interesting experiments can be performed. By

observing the phenomenon of experiment，we have found problems and ask questions，and further analyze and

explore it.

Theoretical approach to realize wide-angle ultra-transparent optics

LIU Zhi-da, GUO Jia-qi, TIAN Bo-yang, WANG Zhao-na

College Physics. 2019, 38(1): 62. doi:10.16854 /j.cnki.1000-0712.180067

Abstract ( 1342 )

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The implementation of wide-angle ultra-transparent optical interfaces is the key to improve the optical

energy utilization efficiency and the imaging quality in complicated optical systems. In this work，the Fresnel

formulas of the interface between the isotropic medium and the anisotropic medium are deduced from Maxwell's equations

and boundary conditions，and the conditions of wide-angle total transmission on the optical interface are

then obtained. On this basis，a new device with the ultra-transparency is proposed at a wide angle range of [-85°，

85°]. The results should provide a new theoretical approach for designing the novel optical devices with highly efficiency

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College Physics. 2019, 38(1): 67. doi:10．16854 /j．cnki．1000-0712．180223

Abstract ( 1051 )

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