We have established a model for the analysis of azimuthal-radial pendulum by Lagrangian mechanics. We list the I agrangian function of the system and consider the influence of air resistance. The theoretical trajectory of the azimuth-radial pendulum is obtained by numerical simulation.The influence of the weight' s mass , the releasing azimuth angle and the releasing radial angle on the maximum displacement in the direction of azimuth was investigated by using the method of controlling variables.The experimental results were in good agreement with the numerical simulation results , which further proved the correctness of our theory.

It introduces an experiment of measuring charge-mass ratio of electron by the method of magnetron controlling. It was focus on analyzing the way of processing the experimental data. In addition, it presents the “Midpoint” method of dealing with experiment data systematically, combining the way of the “Half Saturation Current” and the “Intersection”. The charge-mass ratio of electron was about 1.65×10¹¹ C/kg and 1.81×10¹¹ C/kg with relative errors of 6.25% and 2.84% by using the method of half saturation current and intersection method, respectively. However, the charge-mass ratio of electron was about 1.74×10¹¹ C/kg with relative errors of 1.14% by using the method of “midpoint”. It can be found that the method of “midpoint” can obtain charge-mass ratio of electron with higher precision compared with the method of “Half Saturation Current” and “Intersection”.

Based on the Fourier transform and spatial filtering theory of spectrum, the theoretical analysis of the light intensity and phase modulation of Gaussian beam after spatial filtering by 4F system is carried out. The MATLAB mathematics software is used to simulate the image formed by the high-pass and low-pass filtering of the "light" screen after 4F system. The differential screen was designed by ourselves, and the edge enhancement effect was realized by changing the phase of the diffracted light. The simulation results are in good agreement with the experimental data. Through theoretical simulation, the physical connotation of Gaussian beam Fourier transform and spatial filtering optical phenomena is vividly and deeply revealed, which lays a foundation for the design and effect demonstration of functional filters.

The determination of Young's modulus of wire is one of the important experiments in college physics experiment. This experiment comprehensively trains students' basic physical experiment skills, such as measurement, data processing and measurement skills. In this paper, the teaching content has been expanded. For the aspect of the method, the reference ruler is proposed to measure the distance between mirror rulers and the length of wire, which is difficult to accurately measure, so as to improve the measuring accuracy. For the aspect of the content, the research contents of elastic hysteresis property of materials are expanded by the characteristics of stress corresponding to strain when adding or subtracting weights; In terms of data processing, the least square method and item-by-item difference method are adopted to process the data, the young's modulus values obtained are 1.88454×1011 Pa and 1.88959×1011 Pa, respectively. The relative error between them is only 2%.

The focal length of lens group can be measured by nodal slide. The advantage of using nodal slide is intuitive. Without nodal slide, we can also measure by Newton formula. When using Newton formula, we need to know the position of focus, object point and image point. The usual method is to judge the clarity of the image. Different people's judgment is different，and the error is large. In this paper, the method of object-image parallax comparison is used to judge. First, the whole measuring system is introduced, then the pinpoint system is introduced. Finally, the focus, object point and image point positions are measured by the methodof object-image parallax comparison. Finally, the focal length of lens group is obtained. The relative deviation is 0.13%. At the same time, the focal length of lens group are measured by a nodal slide， and relative deviation is 0.45%. It can be seen that the results measured by the method of object-image parallax comparison are more accurate.

Using the spectrometer, sodium light as the light source, and the self-designed isosceles trapezoidal groove as the liquid trough, a platform for measuring the refractive index of the liquid is built. The refraction angle is easily and quickly determined by the platform, and the refractive index is obtained by programming based on Python software. The refractive index of deionized water and different concentrations of NaCl solution was measured by this method. The experimental results show that the relative error of the refractive index of the solution is far less than 5%. The method is simple in operation, fast in calculation, low in cost, high in accuracy, high in efficiency, and has strong operability and application value. It is measuring liquid refraction. It is a new method to measure the refractive index of liquid.

Electron spin resonance is a new technology application of study the electron structure and dynamics of the species which have unpaired electron. Nowadays ESR has been widely applied in biology and medical science. For example it is used to explore the catalytic mechanism and structure of metal proteins and analyze the structure and function of single molecular magnetism which has metals and residues. At present, one of the microcosmic ESR methods which based on NV centers is applied to explore the object at the nano-scale. The single molecule ESR spectrum has been detected through this technique. In this paper，the application principle and development of ESR technology were summarized, which could be taken as reference for analysis of the protein molecule structure and dynamics, determine the radical reaction process，location of spin-label molecular and other fields.

Based on the GGDC-B type silicon photocell comprehensive experimental instrument,  the basic characteristics of silicon photocells were studied. Through our experiments, it is concluded that as the illumination increases, the output voltage and current of the silicon photocell gradually increase. In a certain range of illumination, as the load resistance increases gradually, the output current is still linear with the illumination. The smaller the resistance of the load, the larger the range in which the output current is linear with the illumination. In the visible range, the sensitivity of a silicon photocell increases with increasing wavelength.

we analyzes experiments of organic glass by using pulse laser marking system, and the changing process of the material and the marking effect are summarized by comparing the experimental data. Adjusting three parameters of different laser marking systems, including marking speed, marking power and marking times are used to achieve a better visual effect of the marking.

Experiment of college physics is the basic course for students of science and engineering to cultivate their comprehensive ability. A laser absorption spectroscopy experimental setup using a mid-infrared quantum cascade laser is employed to detect trace carbon monoxide (NO₂). The experiment can deepen students' understanding of physical concepts and improve their innovation consciousness.

It is a very essential problem in electromagnetism to solve the distribution of magnetic field generated by current-carrying with the method of Bio-Savart's law .As the magnetic induction intensity dB generated by the current element dl on the current-carrying circular coil at a certain point on the axis is oriented in a three-dimensional space, which leads to the result that students generally think it abstract and difficult to understand . The article takes the magnetic field distribution on the axis of the current-carrying coil as an example,concerning about the magnetic field on the axis of the current-carrying coil is measured by the experimental method of electromagnetic induction.The obtained data charts can visually describe the magnetic distribution characteristics on the axis of the current-carrying circular coil, and the experimental results are very proved of  Biot-Savart law. The formula of magnetic induction intensity on the axis of current-carrying circular coil is applied to the teaching mode of combining new experimental technology with electromagnetics theory in practical teaching, so as to make it abstract.Physical concepts and formulas have become more specific and visualized, and have also received good teaching results.

Using the compass function of smart phone and the uniform magnetic field generated by Helmholtz coil, the horizontal component measurement experiment of the earth's magnetic field in common physics experiment is reformed.  The advantages of high sensitivity, no eccen- tricity error and accurate reading of the compass of the mobile phone are fully utilized, and the experimental error is reduced. At the same time, it improves the purpose of using common tools in life to solve physics problems and stimulate students' interest in learning.

In this paper, the method for identification of the origin of dark tea with visible/near-infrared spectroscopy is introduced by taking dark tea as the research object. Dark tea samples were purchased from five different provinces and the spectral data of the corresponding dark tea samples was collected. The dimension was reduced by principal component analysis and the optimal band was selected. The raw spectral data of dark tea samples were preprocessed by convolution-based smoothing, multivariate scatter correction, transformation on standard normal variate, and detrending. Finally, the new spectra and original spectra processed by different pretreatment methods were used to establish a partial least squares regression model on the prediction of the origin of dark tea. The experimental results show that the modeling effect of the transformation on standard normal variate (SNV) for spectral processing is the best; it has the highest coefficient of determination of the test set (RP2), i.e., 0.9627, and the lowest root mean square error (RMSEP), i.e., 0.0255. The study provides a reference for effectively identifying the origin of dark tea, protecting the dark tea brand, and enhancing the image of the national geographical landmark of the brand.

The principle of ultrasonic standing wave in acousto-optic crystal is introduced. Besides, the method based on  acousto-optic diffraction is compared with the method of shadowgraph  in measuring ultrasound velocity, the advantages and disadvantages of the two methods are analyzed, which is helpful to understand the propagation of ultrasonic standing wave in acousto-optic medium more intuitively.

The audio frequency acquisition and amplification circuit consists of four modules:power supply, audio frequency acquisition, voltage amplification and power amplification.As a subject of electronic circuit design, the system has clear design ideas for students and is easy to apply the theoretical knowledge to circuit design.For teaching, the design requirements can be adjusted according to the students' ability to adapt to different levels of students circuit design and engineering practice.Instruct the students to simulate each circuit through Multisim software, weld the actual circuit on the circuit board with components, and finally carry out the test to make the amplifier circuit meet the requirements of output power, load impedance, frequency and other aspects, and carry out the corresponding expansion of experimental functions.

In order to improve the teaching effect of modified digital multimeter experiment in the basic physics experiment, combined with the experience in the actual experiment’s operation, the teaching process of the “Measuring the transistor’s h_FE parameter” part of the digital multimeter modification experiment is further improved, especially for the physics students who have not studied the related electronic technology courses systematically. Also, the teaching effect has been optimized, making the experiments measuring the parameters of electronic components more acceptable for the students majoring in physics at this stage and enhancing students' understanding of modified digital multimeter and its application.

A kind of measuring instrument for liquid viscosity coefficient using 3D laser positioning and temperature controller was introduced. The measuring device uses the three horizontal and one vertical placed laser photoelectric gates on the measuring cylinder to realize three-dimensional precise positioning of falling steel beads, the drop of small steel beads along the central axis of measuring cylinder, and precise measurement of falling time of steel beads. One can measure the liquid viscosity coefficient at different temperature using the temperature controller. The new measuring device has the characteristics of intuitive experimental process, simple operation, accurate measurement data and good repeatability. The instrument can be useful in scientific research and general physics experiment teaching.

The spring elastic coefficient is accurately measured based on the principle of ultrasonic ranging and lever amplification. The device uses an ultrasonic measuring system to accurately measure the expansion length of the spring amplified by the lever principle, and uses the method of pulling the spring up vertically to eliminate the influence of spring gravity on the experiment, so as to accurately determine the deformation and elastic coefficient of the spring. The experimental device is a new device for measuring spring elasticity coefficient accurately. It has the advantages of small measurement error, simple operation and strong intuition. It can be used not only as a device for measuring spring elasticity coefficient accurately, but also as a teaching demonstration device for classroom teaching to stimulate students' interest in physical experiments.

Multistage amplifier circuit is an important teaching content in the course of fundamentals of electronics. In this paper, a typical direct coupling multistage amplifier circuit was analyzed by using theoretical calculation and Multisim simulation, and the positive role of Multisim simulation played in the teaching of the course of fundamentals of electronics was highlighted. Multisim simulation can show the abstract and boring teaching content vividly, which can improve the learning interest of college students. The teaching methodology combining theoretical analysis and Multisim simulation is helpful for college students to better understand and master the teaching content, and then improve the teaching quality and get the expected teaching results.

Poisson bright spot is an important experimental phenomenon which be used for proving the fluctuation of light. Based on the Fresnel diffraction theory, the diffraction processes of Poisson bright spot were simulated by a Matlab program in a computer. The change tendency of the Poisson bright spot and its diffraction rings were studied by different wavelength of incidence light, diameter of the disk, and position of the receiving image. This study shows that single dark ring and multiple dark ring can be realized by suitable conditions, which has potential applications in micro-nano fabrications of semiconductors.

Based on LabVIEW software, the imaging process of Abbe 4F system is designed at all the parts. Object image is generated by two-dimensional grating, and the frequency spectrum is obtained by Fourier transform.  After the frequency spectrum is processed by different filters,  an image plane image is produced by inverse Fourier transform. In the design and simulation of the generated two-dimensional grating and different two-dimensional filters, it is convenient to operate and control the type and size of the grating and the filters. This program plays an active role in understanding the correspondence between frequency spectrum and spatial image.

with the rapid rise and development of  computer technology, Computers are being used more and more frequently in college physics teaching, and computer simulation has become the third important research method  besides experimental research and theoretical research. This paper mainly uses a Matlab numerical simulation software to write a visual application. Image the Maxwell rate distribution function and adjust different parameters by setting. Intuitively and dynamically demonstrate the changing rules, supplementing and perfecting the shortcomings of traditional teaching. Enhance the effectiveness and interest in the learning process of physics knowledge, which improves students' initiative and enthusiasm to study.

With the automatic tracking function of tracker software, we can effectively track the movement of the object. In addition, we can draw the displacement time curve of the object movement in real time, fitting the momentum time curve of the object movement process, and then the law of conservation of momentum can be verified. Compared with the traditional experiment, the process of data processing is simple and the accuracy of the result is higher.

The application of Origin to photoelectric effect experiment is studied. The process of dealing with the experimental data by the software is researched , such as the relation to cutoff voltage and frequency , and volt-ampere properties of photocell. The result shows that the Planck constant, the work function of the metal, and volt-ampere properties of photocell can be clearly obtained by Origin. The relation of cutoff voltage and frequency is linear by software fitting.

Based on error theory, taking the experiment of measuring shear modulus of wire by torsional pendulum method as an example, the systematic error and accidental error of direct measurement are analyzed and judged. With the help of excel data processing tool, the shear modulus of wire is solved by data processing method of standard uncertainty, so as to help students understand and master the basic method of physical experiment error and data processing.

Based on the educational goal of "constructing emerging engineering" and "cultivating emerging engineering talents"，department of physics of Tianjin University has promoted a series of reform scheme of developing advanced basic research courses in physics for undergraduates to solve deficiency problem of scientific research in physical experiment teaching. It is expected to explore new ways for undergraduates to participate in scientific research, strengthen the cultivation of undergraduates' working habits and logical thinking, and cultivate undergraduates' overall innovative ability through this reform scheme. Furthermore, we are aim to explore new ways of scientific research to promote innovative talents cultivating and specialties development, provide experience for other disciplines to carry out related work. Thus, our reform scheme will have great contribution to the construction of emerging engineering and cultivation of emerging engineering talents.

Introduction class is the first section of college physics experiment, it plays the part of guide as well as foundation for experiments. Interest stimulation in order to improve the teaching effect is therefore important for college physics experiment.The teaching work about introduction class based on practical experience is analyzed and discussed.

The demonstration experiment is an important part of the university physics experiment, and plays an extremely important role in training students’ practical ability and innovation ability. Based on the training objectives of physics experiment teaching, combined with the practice teaching of our school for many years, we have made a series of reforms on the traditional demonstration experiment teaching by continuous practice and exploration, and explored a suitable method of physical demonstration experiment teaching for our students.

With the increasing foreign students studying in China, it becomes an important way to teach foreign students different courses in English. It is mainly summarized how the physics experiments have been taught in English in our university. Then, it is put forward that students should be taught with more encouragements besides being criticized and educated appropriately. Finally, the prospect of this course is discussed, and it is suggested that small class teaching and hierarchical teaching should be considered when conditions are permitted.

Taking the goal of talent training in applied local undergraduate colleges and universities as the starting point, and analysis of the teaching current situation of universities physics experiment. Through constructing multi-level, all-round, network edited combination of university physics experimental platform, and improving the existing teaching contents and teaching mode, leading to a university physics experiment teaching model suitable for applied local undergraduate institutions.

Constructing educational model of university physics experiment based on OBE concept, take the “Michelson interferometer measures wavelength of laser” experiments as an example, to carry out educational reform and pilot program of university physics experiment based on OBE concept. After two terms, it is proved that the teaching result of education model based on OBE concept is obviously improved than that of traditional, for example, students can take the initiative to learn, classroom atmosphere is more active, higher efficiency in class and so on.