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- The contribution for general relativity and black hole theory by R. Penrose
- ZHAO Zheng
- College Physics. 2021, 40(2): 1-11. doi:10.16854/j.cnki.1000- 712.200476
- Abstract ( 782 ) PDF (1790KB) ( 272 )
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- Teaching development of the nonlinear characteristics of forced vibration
- DING Hong-sheng, WANG Jia-xi, ZHANG Shi-ping, DONG Jun-jun
- College Physics. 2021, 40(2): 12-17. doi:10.16854 /j.cnki.1000-0712.200335
- Abstract ( 635 ) PDF (1739KB) ( 378 )
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- Study of the range of uniform magnetic field of Helmholtz rings
- MO Yun-fei, ZHOU Qun-yi , HOU Zhao-yang, ZHOU Li-li
- College Physics. 2021, 40(2): 18-20. doi:10.16854 /j.cnki.1000-0712.200137
- Abstract ( 764 ) PDF (1367KB) ( 191 )
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- Discussion on image method within dielectic
- FU Chun-e
- College Physics. 2021, 40(2): 21-22. doi:10.16854 /j.cnki.1000-0712.200300
- Abstract ( 1072 ) PDF (1077KB) ( 391 )
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- Relationship between ground state energy and approximate level in parameter perturbation method
- WU Feng, MENG Li-juan
- College Physics. 2021, 40(2): 23-24. doi:10.16854 /j.cnki.1000-0712.200121
- Abstract ( 676 ) PDF (947KB) ( 144 )
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- An effective method of measuring the velocity of sound in metal rods with DIS
- YAN Qian, ZHU Fei-xia, YUAN Zheng-neng, WANG Kun-lin
- College Physics. 2021, 40(2): 25-31. doi:10.16854 /j.cnki.1000-0712.200105
- Abstract ( 603 ) PDF (2085KB) ( 187 )
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- New discussion on data processing of Millikan oil-drop experiment
- ZHENG Xue-li, LI Qiao-mei, WANG Tao, HAN Zhong, LEI Di
- College Physics. 2021, 40(2): 32-35. doi:10.16854 /j.cnki.1000-0712.200070
- Abstract ( 950 ) PDF (1345KB) ( 213 )
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- Re-understanding the experiment of Millikan oil drop
- DONG Jian
- College Physics. 2021, 40(2): 36-41. doi:10.16854 /j.cnki.1000-0712.200130
- Abstract ( 941 ) PDF (1493KB) ( 296 )
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- Experimental study of refractive index of edible oil based on spectrophotometer
- LI Xiao-kang, XU Shi-jun
- College Physics. 2021, 40(2): 42-47. doi:10．16854 /j．cnki．1000-0712．200182
- Abstract ( 362 ) PDF (1527KB) ( 91 )
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- Exploration and study of improving course teaching quality based on bottom line management
- LI Chen-xia, SHEN Wei-min, SHEN Chag-yu, KANG Juan, ZHANG Yan, FEN Gui-lan, JIN Shang-zhong
- College Physics. 2021, 40(2): 48-51. doi:10.16854 /j.cnki.1000-0712.200212
- Abstract ( 588 ) PDF (1439KB) ( 78 )
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- Sharing online teaching cases of college physics course
- WANG Li, CUI Jin-yu
- College Physics. 2021, 40(2): 52-54. doi:10.16854 /j.cnki.1000-0712.200264
- Abstract ( 809 ) PDF (1962KB) ( 179 )
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- A method to improve the online teaching quality of college physics during the pandemic period
- ZHANG Zi-jing, LIU Li-ping, ZHAO Yuan
- College Physics. 2021, 40(2): 55-58. doi:10.16854 /j.cnki.1000-0712.200281
- Abstract ( 528 ) PDF (1269KB) ( 112 )
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- Generalized thermal wavelength: definition，significance and applications
- LI Xin-yu, ZHANG Zi-yi, WANG Xin, LIU Quan-hui
- College Physics. 2021, 40(2): 59-62. doi:10.16854 /j.cnki.1000-0712.200139
- Abstract ( 1092 ) PDF (1125KB) ( 168 )
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- Virtual simulation and hardware improvements of the laser Doppler velocimetry experiment
- MAO Meng-hui, SONG Zhe-xiang, LUO Tian-hai, CAI Wei,
- College Physics. 2021, 40(2): 63-69. doi:10.16854 /j.cnki.1000-0712.200297
- Abstract ( 752 ) PDF (2445KB) ( 292 )
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- A brief illustration on some problems in one-dimensional quantum scattering
- YING Wen-xiang, PENG Kai-yue, CAO Long
- College Physics. 2021, 40(2): 70-74. doi:10.16854 /j.cnki.1000-0712.200086
- Abstract ( 628 ) PDF (1305KB) ( 266 )
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- Visualization analysis of infinite potential wells
- XIAO Guang-yan, CHEN Feng-xiang, WANG Li-sheng
- College Physics. 2021, 40(2): 75-79. doi:10.16854 /j.cnki.1000-0712.200289
- Abstract ( 778 ) PDF (2895KB) ( 306 )
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- Computer simulation of bicycle system
- JIANG Xing-yu
- College Physics. 2021, 40(2): 80. doi:10.16854 /j.cnki.1000-0712.200146
- Abstract ( 668 ) PDF (1713KB) ( 134 )
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This paper presents the important contribution for general relativity and black hole theory given by R. Penrose who was awarded the 2020 Nobel Prize in physics. That includes the famous singularity theorem，Pen-rose diagram，Penrose process and the cosmic censorship hypothesis. The friendship and co-operation between R.Penrose and S.W. Hawking are introduced. The discovery of a supermassive compact object at the center of our gal-axy by R. Genzel and A. Ghez who were also awarded the 2020 Nobel Prize in physics，is briefly introduced.

Forced vibration is an important teaching content in both college physics and college physics experiments.In order to make students understand the nonlinear characteristics of the forced vibration more deeply，the nonlinear correction of the forced vibration equation is carried out based on the nonlinear factors and experimental data involved in the Pohl resonator，and the nonlinear characteristics are discussed by numerical analysis. By introducing the Duffing equation of hard spring type，the evolution of the system from periodic motion to chaotic state is discussed. The relatively stable equilibrium point in forced vibration is compared with the singular attractor to expand the teaching content of nonlinear vibration.

The analytical solutions of the magnetic field of Helmholtz rings in the rectangular coordinate are derived，and they are dimensionless. The components of magnetic field are obtained by means of the complete elliptic integral of first and second kinds. The distribution of magnetic field is plotted by means of MATLAB. It is found that the range of uniform field is octopus shape. Furthermore，the change of the range of uniform field with the distance between two current coaxal rings is discussed

The method of images is a mathematical tool to solve the electrostatic differential problem，i.e.，introducing

image charge outside the solved space，and making the total field formed by the image charge and the

source charge satisfy the boundary. When this method is applied to the presence of adielectic，it will be found that

the choice of image charge is not unique. This also accords with the uniqueness theorem of the electrostatic problem，

because no matter what kind of image chargeis，the total field is the same. From the total field，the amount of

bound charge can be obtained. At this time，it will be further found that the reisonly one kind of image charge equal

to the amount of bound charge.

Combining the parameter perturbation method with the wave functions that obeys
space change symmetry，
the ground state energy ( GSE) of the helium atom is calculated from the
second to the twelfth level approximations.
It is found that，with the increase of the level，the ground energy and its
change decrease，and the absolute
error between the calculated GSE and experiments exists small fluctuation.
Therefore，the selection of approximate
levels is vitally important for the accurate GSE calculation of the
atom.

An effective method of measuring the velocity of sound in metal rods is
introduced by combining the
standing wave method with acoustic sensors. A metal rod is fixed at its
midpoint and vibration along its length is excited
by rubbing it. A longitudinal standing wave is generated in the rod and
sound waves are produced in the air.
The digital information system ( DIS) is used to collect the sound signal
and directly to display acoustic wave forms
on the screen. The velocity of sound in the metal rod is then calculated
and determined by measuring the fundamental
frequency of sound waves in conjunction with the wavelength. The sound
velocity in four different metal materials
( including aluminum，steel，brass，and copper) is measured respectively. The
experimental results showed that the
sound velocity obtained by this method is consistent in the same material
metal rods of different lengths. The relative error of the sound velocity
between the measured values and the well-known standard values in various metal
materials
is less than 6.00%. One advantage of this new method is that it can turn
the acoustic signal into visible waveforms.

Therefore，calculation parameters can be extracted directly and accurately from the waveforms.

The Millikan oil-drop experiment is one of the classic experiments in university
physics，and the

elementary charge can be calculated by experimental data processing. The experimental methods used by each university

are basically identical，but the experimental data processing methods are various. The data processing combined

with multiple methods is put forward to reduce the error caused by the data processing method，in which the

data is pre-processed by grouping and processed by the least square method based on graphic method and the result

shows that the error is significantly reduced. The ideas in this paper confirmed by five teaching classes are feasible

and valid，which can be applied and promoted in actual teaching.

The experiment of Millikan oil drop was considered to be appropriate for
demonstrating the charge

quantization，but the quantity of electric charge is not easy to be accurately measured by it，because there are many experimental difficulties need to be overcome. Many people expected to decorate the results with a late algorithm.The Brown motion of oil droplets was one of the important factors which had an impact on the balance voltage and the free fall time of the oil droplet. If reasonably dealing with it，the accuracy of the measurement could improve. Combining with the charge-numbering graph method，the charge quantization could be demonstrated concisely，and

the more accurate value of Meta-charge could be obtained. The distribution characteristics of the charge measurement

error is analyzed，and it is properly explained with the limit of the number of significant digits of the measurement data. It settles a theoretical foundation for selecting the suitable oil droplets.

In order to get the optical dispersion specificity of different edible oils，the
change characteristics of

its refractive index with the wavelength must be studied. After ignoring the scattering effect of light，a new doublelayer

slide model for the spectrophotometer has been established，the slide is used to hold the rapeseed oil，sesame

oil，kitchen waste oil，adulterated rapeseed oil，adulterated sesame oil，respectively，the transmission spectrum of

380～1500 nm is obtained experimentally. Further，the change characteristics of the refractive index in the above

five oil products with the wavelength are studied. The results have shown that the refractive index of five oil products

is more similar with the change characteristics of wavelength，and the characteristic peaks of refractive index are all

appeared at 1210 nm and 1400 nm wavelength; the refractive index of each oil product is significantly different at

its characteristic peak，the refractive index of five oil products at the wavelength of 1210 nm is 1. 512，1. 472，

1.456，1.576 and 1.612，respectively. This study has confirmed that the new double-layer slide model is feasible，

the common refractive index characteristic value and the common characteristic spectrum have indicated that there

are many related components in the different oil products. The refractive index characteristic value of five oil products

at the wavelength of 1210 nm can be used as an effective index for the identification of oil products.

Aiming at the problems of outdated teaching methods，lax process management，serious non-rigorous

exam process，and difficulty of teaching quality control in traditional specialty courses，teachers of optical principles

at China Jiliang University have explored and reformed the bottom-line management teaching.Through passing exams，

basic training systems，formative evaluation reforms and other methods，students can truly meet the basic requirements

of the curriculum，instead of allowing students to pass the curriculum assessment by reducing the difficulty

of the test papers，narrowing the scope of the exams，and even disguised questions.Solving the problems that

students，teachers and administrators are most concerned about in the course teaching at present.For students，they

can solve the basic problems in the course learning in a timely manner without significantly increasing the burden，

fully understand the basic methods and efforts of the course assessment，and clear ways to improve their ability and

obtain help from teachers.Practice has shown that teaching reform based on bottom-line management has achieved

good results in improving student learning efficiency，reducing teachers'repetitive work，and improving the quality of

curriculum teaching.

The setting of college physics course in Yingkou Institute of Technology is introduced in this paper.

The online teaching cases of college physics course in our university are shared from three aspects: preparation of

online teaching resources，design of online teaching activities and methods of course assessment.The online teaching

during the pandemic has opened a new door for the teaching reform of college physics course in our university.This

teaching attempt will be continuously improved in the future teaching practice.

For the demand of online teaching during the pandemic period，a new online teaching method based

on real-time feedback of question choice is proposed by considering the characteristics of large class teaching of college

physics courses and combined with the application experience of online MOOC courses and students' learning

habits.In this paper the problems faced in the online large-class teaching of college physics courses are analyzes

first，then the implementation plan of this method is comprehensively described through the designs of question

time，question type，assessment methods of choice question.Finally，through one semester's teaching practice，the statistical

results have showed that this method should effectively improve the quality of online teaching.

Photon gas and highly degenerate quantum gases are not classical ideal gas at all，and each of them has its own mean momentum from which a generalized thermal wave length can be thus defined，and the usual thermal wave length is an irrelevant concept.For a non-degenerate system，this wave length converges to the usual thermal one form a matter particle.For a degenerate system，the dimension of thermodynamic system must be larger than this generalized thermal wavelength，which leads to a criterion on the minimum dimension of the thermodynamic system.For some typical systems，we use the criterion to give their minimum dimensions.

Due to the limited sampling rate of hardware and the weak auto-processing performance in the traditional

laser Doppler velocimetry experimental system，virtual simulation and hardware improvements of the system

are carried out in this work.To develop the virtual simulation，Unity 3D and Matlab Apps are employed to model the

experimental principles and the related signal processing methods.In this way，students could gain a deeper understanding

of the experimental system. Meanwhile，for hardware improvements，a convenient high - speed data

acquisition system is constructed by using LabVIEW programming and digital oscilloscope.And then the sampling rate of the existing hardware is increased from 50 MSa /s to 2 GSa /s.In the parts of software system，various digital

processing modules，such as digital filtering and automatic measurement，are realized to highly improve the performance

of the current experimental system.This work provides a reference for the teaching content and system design of

laser Doppler velocimetry.

We give a simple discussion on the methodology of one-dimensional quantum scattering problems.

Some problems and misunderstandings in one-dimensional quantum scattering are explained and clarified.

With a computation software，many common in finite potential wells are visualized，and a corresponding

GUI interface is designed to select different potential wells.After a potential well is selected and the corresponding potential

well parameters and quantum numbers are set，the wave function，probability density function of low dimensionalgrangian function of any system with finite degrees of freedom and the constraints are provided，the approximate solution

can be found. And this simple method can be applied to the approximate calculation of the bicycle system to

analyze the motion and stability of the bicycle.

A bicycle system is a complicated one with non-complete constraints，which can be solved by the

Euler-Lagrange equation according to least action principle. The approximate calculation is solved by using the

difference instead of the differential and methods to correct the truncation error. Using MATLAB，as long as Lagrangian function of any system with finite degrees of freedom and the constraints are provided，the approximate solution

can be found. And this simple method can be applied to the approximate calculation of the bicycle system to

analyze the motion and stability of the bicycle.