An experimental device for measuring liquid viscosity coefficient was designed and built by using falling film flow. The model was modeled according to the N-S equation of incompressible liquid and combined with boundary conditions. The thickness of liquid film is calculated by measuring the surface velocity of liquid film. The viscosity coefficient of castor oil was measured at different flow rates. The relative accuracy of viscosity coefficient measured at different dip angles was basically the same, and the relative error was below 8%. The application conditions and error sources of the device are analyzed. The thickness of liquid film was compared and verified by total internal reflection method. This study enriches the teaching content and method of measuring liquid viscosity coefficient, helps students to master relevant knowledge of fluid mechanics and improve comprehensive design ability.

At the teacher meeting of Chinese Undergraduate Physics Experiment Competition (CUPEC) held in January 2020, teachers played in role of students. All the participated teachers finished the task by five main periods, which include doing experiment, answering the competition worksheets, correcting papers, group discussion, summary and report. In this paper, we summarize the role inversion teacher meeting, and discuss the direction of physics experiment teaching reform from the aspects of experiment content setting, improvement of experimental teachers, the cultivation of students and teachers' communication, so as to explore the ways to improve the quality of undergraduate physics experiment.