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- Taking electromagnetics as an example to talk about ideological and political education as a fertile soil for students’growth
- WU Xiao-shan, SUN Liang, ZHANG Hai-jun, LIU Jun-ming, XIN Bei
- College Physics. 2021, 40(3): 1-3. doi:10.16854 /j.cnki.1000-0712.200328
- Abstract ( 2759 ) PDF (914KB) ( 1096 )
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- Study of the elastic potential energy of a spherical body in micro deformation
- YU Feng-jun, TANG Zhen-jie, TIAN Jun-long, ZHANG Xi-wei
- College Physics. 2021, 40(3): 4-7. doi:10.16854 /j.cnki.1000-0712.200176
- Abstract ( 1210 ) PDF (1192KB) ( 292 )
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- The size effect of parallel-plate capacitor
- CAO Xiao-ge, YANG Yang
- College Physics. 2021, 40(3): 8-11. doi:10.16854 /j.cnki.1000-0712.200308
- Abstract ( 1236 ) PDF (875KB) ( 700 )
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- Motion analysis of positive charge in uniform obliquely intersecting electromagnetic field under non-relativity
- SHAO Yun, XU Shi-ye
- College Physics. 2021, 40(3): 12-18. doi:10.16854 /j.cnki.1000-0712.200372
- Abstract ( 1001 ) PDF (1016KB) ( 286 )
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- Analysis of vectors and their vector derivatives in Electrodynamics
- HU Xiang-ming
- College Physics. 2021, 40(3): 19-24. doi:10.16854 /j.cnki.1000-0712.200167
- Abstract ( 1680 ) PDF (876KB) ( 1615 )
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- Application of geometry in solving problems of relativity theory
- FENG Xiao-ming, CHENG Min-xi
- College Physics. 2021, 40(3): 25-28. doi:10.16854 /j.cnki.1000-0712.200148
- Abstract ( 859 ) PDF (1459KB) ( 304 )
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- Modification of the standing-wave experiment equipment
- MIAO Yong-ping, SUN Er-ping, LI Zhong-li, DAI Kun,
- College Physics. 2021, 40(3): 29-32. doi:10.16854 /j.cnki.1000-0712.200178
- Abstract ( 1824 ) PDF (722KB) ( 1642 )
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- Analysis of the simple pendulum with smartphone magnetic sensor
- WANG Jin-hui, SUN Cun-ying, ZHOU Hong, WANG Yu-xing
- College Physics. 2021, 40(3): 33-37. doi:10.16854 /j.cnki.1000-0712.200388
- Abstract ( 1694 ) PDF (2305KB) ( 1540 )
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- The experiment of sound velocity measurement by air column resonance based on simple device
- JIAN Zhi-jian, ZHOU Yan-ming, XIE Zhong
- College Physics. 2021, 40(3): 38-42. doi:10.16854 /j.cnki.1000-0712.200165
- Abstract ( 1706 ) PDF (873KB) ( 344 )
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- Optical beat based on microwave frequency difference conversion
- WANG Yun-xin, WANG Da-yong, YANG Deng-cai, LI Ping-xue, RONG Lu, ZHAO Jie
- College Physics. 2021, 40(3): 43-47. doi:10.16854 /j.cnki.1000-0712.200269
- Abstract ( 934 ) PDF (1152KB) ( 195 )
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- Exploration on the online teaching mode of university physics in engineering colleges during the COVID-19 epidemic
- NIU Jin-yan, LIU Jia, MU Li-juan, HE Jian-li, CHEN Wei-li
- College Physics. 2021, 40(3): 48-50. doi:10.16854 /j.cnki.1000-0712.200426
- Abstract ( 876 ) PDF (2245KB) ( 482 )
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- Practice of online and offline blending-learning mode of college physics based on the construction of golden course
- WANG Hui, WU Ping, ZHU Hao, ZHANG Xiao, XIE Dong
- College Physics. 2021, 40(3): 51-55. doi:10.16854 /j.cnki.1000-0712.200379
- Abstract ( 967 ) PDF (1628KB) ( 400 )
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- Improvement of the experiment using a single pendulum to determine gravitational acceleration
- LIU Yu-qi, TAN Yu-sha, WEI Xian-tao, ZHANG Quan, ZHAO Wei, ZHU Ling
- College Physics. 2021, 40(3): 56-61. doi:10.16854 /j.cnki.1000-0712.200215
- Abstract ( 4174 ) PDF (715KB) ( 597 )
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- Dynamic behavior demonstrator of spring pendulum
- HE Yu-ji, WANG Jin-zhi, LIANG Zhuo-fan, LI Qing-feng
- College Physics. 2021, 40(3): 62-65. doi:10.16854 /j.cnki.1000-0712.200224
- Abstract ( 909 ) PDF (1166KB) ( 354 )
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- The equilibrium stability of two connected bubbles
- SHENG Tian-shuang¹, YU Qiu-yu²
- College Physics. 2021, 40(3): 66-68. doi:10.16854 / j.cnki.1000-0712.200184
- Abstract ( 893 ) PDF (797KB) ( 362 )
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- An electric dipole and a mechanical pendulum
- JING Yu-wei, WU Pu-xun
- College Physics. 2021, 40(3): 69-71. doi:10.16854 / j.cnki.1000-0712.200396
- Abstract ( 1093 ) PDF (643KB) ( 712 )
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- Influence of interference on optical properties of ITO films
- LIU Zi-jian, ZHAO Ya-li, LI Xiao-yun, LUO Xiang-yu
- College Physics. 2021, 40(3): 72-78. doi:10.16854 / j.cnki.1000-0712.200222
- Abstract ( 1254 ) PDF (1264KB) ( 446 )
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- Solving the Schrodinger equation with the relaxation method
- LIU Guan-fu, YU Cong
- College Physics. 2021, 40(3): 79. doi:10.16854 / j.cnki.1000-0712.200219
- Abstract ( 1197 ) PDF (1415KB) ( 295 )
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How to construct a better course is discussed in this paper by
taking“Electromagnetics”as an example.

It is also discussed how to embed the three elements of“Materialism”，“From practice to practice”，“Seek

truth from facts”into the course，and let them rooting and germinating in students’mind.

In this paper，we study the elastic potential energy of an elastic sphere when it
is deformed into a

long rotating ellipsoid while keeping its volume constant. Firstly，the displacement function is determined by the

principle of minimum potential energy and physical conditions. Then，according to the relationship among elastic

potential energy density，strain and displacement，the elastic potential energy is obtained by integral calculation，

and the beneficial discussion is made.

It is investigated in this paper how the capacitance of parallel circular-plate
and rectangular-plate

capacitors varies with the size，respectively. For each kind of capacitor，first it is assumed that charge is distributed

uniformly on the plate，then approximate values of capacitance can be obtained conveniently，afterwards more accurate

values are obtained via finite element simulation using Ansoft. By comparison，it is discovered that results obtained

using the approximation of uniform charge distribution can reflect correctly the tendancy how the capacitance

varies with the size，which is better than the capacitance formula of parallel-plate capacitor in textbooks; however，

those values are smaller，since charge is not strictly distributed uniformly on the plate，but less in the middle and

more on the edge.

In this paper，the dynamic vector analysis of the positive charge +q in uniform
obliquely intersecting

electromagnetic field under non relativity is carried out，and the charge’s motion is decomposed into: 1) uniformlyaccelerated linear motion along the direction of magnetic field; 2) uniform linear motion perpendicular to the direction of electric and magnetic field; 3) circular motion with uniform rate perpendicular to the direction of magneticfield. Therefore the complete kinematics equations of electric charge are deduced. Then，the kinematics equations are reduced and simplified，and the projection trajectories of charge in the xy plane under different initial velocities are made and analyzed，of which characteristics and internal reasons are pointed out. An example is given to illustrate the space trajectory of electric charge，and the commonness of it is pointed out. Three special cases of uniform orthogonal electromagnetic field are discussed. In addition，it is pointed out at the end of the paper that the core idea of the method in this paper is the switching of reference frame.

Of all four courses of mechanics，Electrodynamics is thought to be relatively
more difficult to learn

than others by many students.Depending on my own teaching experience，I make a rough analysis about it. It is

shown that the difficulty lies in whether learners realize the fundamental role of vectors and their vector derivative

operations. Since Electrodynamics treats both the time evolutions and the local interactions in the electromagnetic

systems，any part of the course is based on the vectors and their vector derivative operations. Therefore both the

physical law expressions and the related mathematical calculations are relatively complicated. Only when the

learners understand the definitions of the vectors and are good at their vector derivative operations will they express

the physical laws in a reasonable way and understand their applications.

In solving the problems about reference frame transformation in the theory of relativity，it is often required

to have a long and complicated calculation. Two-inertial-system mapping is often used to transform the computational

problem into a geometric problem. This method is quick and intuitive but hard for beginners to grasp. To

express the dynamic process of Lorentz transformation and transfer physical pursuit invariance values，a new geometric

method named hyperbolic rotation was put forward. Based on the two inertial system mapping，the hyperbolic

rotation was carried out based on time-interval invariance and the final geometric results were determined by the restriction

of causality. There was an example to explain the application of two geometric methods in detail.

The Analysis on the standing wave experiment is carried out. Reasons are found
out and then some

improvements on the experiment equipment are provided. On the one hand，directly measurement of string tension

instead of the weights is introduced to measure the string tension; on the other hand，a micro-adjustment

mechanism is assembled to slightly change the length and the tension of string. Thus，experiments on relations of

string tension，wavelength，frequency and string density can be carried more accurately and conveniently.

The magnetic sensor ( electronic compass) in the smartphone is used to study the
magnetic simple

pendulum based on the Phyphox APP. The results showed that the behavior of magnetic induction with time varies

with different amplitude angles. Only when the amplitude angle is less than 1°，the simple harmonic vibration of the

simple pendulum could occur. The curve of magnetic induction via time at different amplitude angles can be described

by magnetic dipole model combined with large angle pendulum formula. The local gravity acceleration measured

by the smartphone magnetic sensor is 9.868 m/s2 . Due to the small air damping of the magnetic pendulum，the

experimental error is only 0.8%.

A simple set is designed to study the resonance of air column and to measure
the sound speed. Because

of the limitation of the simple equipment used in the experiment，the air column is short and thick，so it is

necessary to consider the endeffect caused by the acoustic radiation of the orifice during the resonance. The experiment

is easy to be implemented，and the data processing is helpful for training students’ability of mathematical

modeling，data mining and extraction.

Optical beat frequency is an important teaching content in college physics and
optical experiment.

Due to the central wavelength drift of the laser，it is difficult to produce observable beat signal in the experiment.

Inspired by the transformation between electric domain and optical domain in microwave photonic technology，an

optical beat frequency method based on microwave frequency difference conversion is proposed. By means of intensity

modulation and phase modulation，two microwave signals with small frequency difference are modulated to the

same optical carrier. Two stable optical signals with minimum frequency difference are obtained by combining with

optical filter. Optical beat is realized by using photoelectric detector. Visual low-frequency beat signal is obtained

by the simulation and experiment. This method provides an experimental scheme for college physics and optical experiments

combined with the cutting-edge of science. It can expand the teaching content and depth，and can also

help to cultivate students’scientific literacy.

In order to meet the online teaching requirements during the COVID-19 epidemic
and ensure the implementation of university physics teaching，the online teaching
mode is explored in the beginning of this semester.
After investigating the characteristics of online teaching on different
teaching platforms，it was decided to use
Dingding and Rain Classroom as the main teaching software，and the network
teaching platform as the teaching resource
uploading platform to ensure that students have online resources. Rain
Classroom is taken as the unit test and
classroom test platform because of its function of data recording and
analysis. Through implementing the whole
process of the teaching mode of pre - class preparation，live discussion and
learning in class，and after - class
review，not only the online teaching is effectively carried out，but also the
student’s learning data is collected to
master the student’s learning situation and provide guarantee for online
teaching of university physics.

In this paper，the teaching reform and practice of online and offline
blending-learning mode are

continued to be carried out in the course of college physics in the recent years. During the practice，according to the

student-centered education concept and the construction standard of golden course，not only the reform of teaching

methods based on information technology is carried out，but also the high-level and challenging degree of teaching

content are improved and the practice of a new teaching mode of knowledge inquiry，speculation，and expansion are

promoted.Through the design and practice of online and offline blending - learning mode of college physics，

students’deep and personalized learning is effectively enhanced. In the post-epidemic era，it is of important reference

value for teachers and students to achieve high-quality online and offline hybrid teaching.

In the experiment of measuring the gravity acceleration by a single pendulum，it
is difficult to determine

the pendulum length very accurately. Under the better measurement conditions，the measurement accuracy

could generally reach the order of millimeter，and the relative error of the measured gravity acceleration is generally

about 1%. In order to solve this problem，in this paper the measuring precision was improved to 0.02mm by using

avernier caliper connected with a cycloid to accurately measure the change of pendulum length instead of directly

measuring the pendulum length. At the same time，the swing period of the pendulum ball is measured by a photoelectric

gate，and the different cycloid material and diameter are compared and analyzed.The measurement error of

acceleration is controlled within 0.1%.

In the non-linear conservative system，the spring pendulum has simple structure
and

typical motion characteristics. In this paper，the motion equation of the spring pendulum system is

obtained through the theoretical analysis of the Lagrangian equation，and the motion is

decomposed in the radial and tangential directions. The spring pendulum demonstrator and

experimental software are designed by using image processing technology to visu- alize the motion

track and time sequence diagram The trajectory drawn by the software is in good agreement with the

theoretical results.

To study the equilibrium stability of the bubble connecting device，the concept
of bubble

coordinate is introduced.Basedon this，the minimum energy method is used to quantitatively analyze

the influence of bubble's initial state on bubble's equilibrium stability. The results are in full

agreement with the qualitative analysis. Mean- while，the experiment shows that the error between

the results of numerical computation and the experiment results are very small. So the validity

and accuracy of the equilibrium stability analysis of the bubble connecting device by using the

minimum energy method are verified.

The electric dipole，as one of the basic models of electromagnetism，has an
exotic field

distribution， which in the normal textbooks is given by either the gradient of the

electric potential or the vector superposition method. These mathematical approaches are

hardly helpful for students to understand the features and the unique picture of the

dipole field distribution. Here，based on an analog of the mechanical pendulum and the

electric di- pole，we give the two forms of the dipole field，especially the free-of-coordinate

one，and practical applications of this analog. Our paper can benefit beginners in seeing the inner

relation of knowledges，understanding the features of the dipole，and appreciating the power of

analogy thinking.

In order to reveal the influence of ITO film thickness on optical
transmittance

and colouration，the visible transmittance， average transmittance and the transmittance

at 550 nm ( the human eyes sensitive wavelength) were calculated by mean of

TFCalc optical film design software. The influence of thickness and incident angle on the

transmittance and colouration of ITO films was investigated by the theory of film interference. The

results suggested that a series of transmission peaks appear with increasing the ITO film

thickness. With the in- crease of the film thickness，the optical transmittance of ITO films is

serrated as well as the average transmittance and transmittance at 550 nm. Accordingly，the

colouration of ITO film changes periodically. When the incident an- gle increases from 30 to 60

degree，the colouration of the ITO films with thickness of 300 nm changes from dark

purple to bright purple. The color chart of ITO films was established in this paper，which provides

technical support for industrial control and improvement of colouration of ITO films.

The most common method to solve ordinary differential equations is the
shooting

method based on Runge Kutta method. The shooting method is commonly used，but the calculation

time is long. When the boundary conditions are more complex or more sensitive，the relaxation

method is better.In this paper，the Schrodinger equa- tion is solved by the relaxation method and

compared with the analytical solution. It is found that the numerical so- lution obtained by

relaxation method is in good agreement with the analytical solution，and the accurate solution can

be obtained quickly by relaxation method.