When a certain wavelength of light passes through the liquid，some of the light intensity will be absorbed by the liquid，and the absorption ability of different concentrations of liquid to the light intensity will be different．The remaining light intensity after liquid absorption will still cause photocurrent to be generated in the phototube．Based on the experimental principle of photoelectric effect，the corresponding photocurrent of the same liquid at different concentrations was measured．The calibration curve of the two is drawn，and the linear equation of the two is fitted by computer．That is，the corresponding concentration of the liquid can be calculated only by measuring the photocurrent of the liquid after light blocking through the photoelectric effect tester．

The traditional method can effectively improve the magnification，but additional devices are needed to determine the reflection times．Through the combination of a large plane mirror placed in a slant to the mirror of the optical lever，the number of reflections is accurately controlled to 2 levels，and the optical path is increased while an angle change is increased．Finally，the magnification is increased to 4 times of the traditional lever method．Theoretical analysis and experimental results show that the oblique double mirror method is used to measure the Young’s modulus of metal wire． The experimental results are in good agreement with the theoretical analysis，which verifies the effectiveness of the method and theory．In addition，the amplification factor is as high as 84．36 times in the limited space not more than 80 cm．

The influence of the grating on the spectrometer table which rotated a certain angle on the change of diffraction angle is analgzed theoretically，and through the Matlab software to make surface chart which can visually observe the change of diffraction angle as you increase the rotation angle and the diffraction angle． Compared the experimental measurements with theoretical derivation，found that the grating rotated a certain angle，the change of diffraction angle used in the calculation increases with the increase of the diffraction angle，and it will cause some errors in the calculation of wavelength．

“Curriculum ideological and political education” is an important measure for colleges and universities to realize the fundamental task of values establishment and people cultivation． College physics experiment course is a good carrier of “curriculum ideological and political education”．The infiltration of ideological and political education into the teaching of college physics experiment course can make the ideological and political education contained in college physics experiments present vividly in the minds of students，which is favour of cultivating the students’scientific literacy．In order to find an effective way to combine curriculum teaching with ideological and political teaching，the overall teaching design of “college

physics experiment”for“Ideological and Political Course”has been carried out．Taking Newton’s ring as an example，how to integrate the ideological and political elements of the course into all aspects of college physics

experiment teaching has been discussed，in addition，student evaluation and teaching summary are given．

Ｒainbow and secondary rainbow are magical natural phenomena in the atmosphere． In order to visually observe the rainbow and secondary rainbow and explore their optical phenomena and influencing factors，we designed two demonstration devices for reproducing the rainbow and secondary rainbow，which can reproduce the phenomenon of the rainbow and secondary rainbow at the same time，measure the observation position and the incidence of the rainbow and secondary rainbow．The angle of light，explore the reasons and conditions of the formation of rainbow and secondary rainbow phenomenon． Through the observation and analysis of the rainbow and secondary rainbow produced by transparent glass balls with different diameters，it is indirectly proved that the larger the raindrop，the more significant the rainbow and secondary rainbow phenomenon，and the exit angle of the rainbow and secondary rainbow has nothing to do with the diameter of the water drop．The rainbow and secondary rainbow demonstration device has simple operation，clear phenomenon and low cost．It is very suitable to extend to classrooms or science and technology museums to help understand the rainbow phenomenon and its optical principles．

The experiment is based on the improved Jolly’s scale，and a device for measuring stiffness coefficient using Hooke’s law is designed by using the principle of optical lever．The device obtains the rotation angle of the lever by recording the distance between the initial and final positions of light movement，calculates the extension length of the measured spring．The experiment overcomes the influence of the deadweight of the spring，reduces the measurement error，makes the experimental phenomenon more intuitive，and enhances the experimental measurement accuracy．

Based on the traditional falling ball method to measure the liquid viscosity coefficient，combined with Millikan oil drop experiment，the oil drop in the air is simulated as a small ball moving in the liquid，so that the idea of measuring the liquid viscosity coefficient by falling ball method can be applied to the measurement of air viscosity coefficient．The CCD imaging system is used to capture the state of oil droplets and use intelligent phones to record their movement process．The“ Tracker ”software is used to collect relevant physical quantities，and finally the air viscosity coefficient is calculated．

With the help of the powerful plotting, animating, and programming functionalities of theMathematica software,and based on relevant formulas and laws of wave optics, several typical polarized lightphenomena have been accurately and dynamically simulated.The series of animations developed in this studyare vivid, intuitional, and thus very helpful for students to increase their knowledge of polarized lightphenomena and deepen their understanding of polarized light laws.This study adds colorful teaching resourcesto the optics course and also fully demonstrates the powerful capability of the Mathematica software to developphysics teaching resources.

Experimental researches on the physical characteristics of rotating liquid are required for collegestudents in the 2lst century.Due to the short of experimental skills ,students usually have experimental errors irthe process of experimental operation, which can affect the measurement accuracies of the gravitationalacceleration in the data processing phase.lt innovatively carried out different types of experimental errors tostudy effects of the deviation angle(a) of the transparent screen from the horizontal orientation , laser verticalincidence point offset( Ax) ,and deviation angle(y) of laser incident light from the vertical direction angle onthe acceleration of gravity measurement.The analysis results show that a deviation angle of 5° of the transparentscreen from the horizontal orientation can lead to a 5.5% error in the acceleration of gravity measurement.Aaser vertical incidence point offset about 5 mm can result in an experimental error of about 12%.Moreover,a16.3% measurement error can be obtained by an incident light deviating 5° from the vertical direction to theleft while the error grows to 22.9% when the laser incident light deviates 5° from the vertical direction to theright. These findings can provide theoretical foundations and teaching tips for teachers in colleges anduniversities to reduce the measurement error of gravity acceleration when guiding students to conductexperiments on rotating liquid characteristics.

With alcohol solution，NaCl solution and sucrose solution as research objects and Michelson interferometer as carrier，the relationship between refractive index and concentration of these solutions at 20 ℃ was studied by titration．By fitting the variable relationship between the concentration and the refractive index， the functional relationship n(c)of the refractive index n with the concentration c is obtained by integral operation，and then the refractive index of the solution at any concentration is given．This experiment can not only be used as a design experiment or an extension experiment of college physics to cultivate students’ practical ability and innovative ability，but also can be used to measure the refractive index of solutions at different concentrations．It would have a good prospect in application．