物理学是一门以实验为基础的自然学科，教师在课堂上的实验演示成功与否，直接影响学生对知识的正确理解和掌握，特别是一些平常生活中少见的物理现象，演示实验的效果就显得更加重要了．然而有的实验仪器，却偏偏不尽人意．近几年，教学仪器站给我校分配来的“自感演示仪”就 Physics is a natural subject based on experiments. The success of the teacher’s demonstration in the classroom directly affects the students’ correct understanding and mastery of knowledge, especially the rare physical phenomena in ordinary life, demonstrating the effect of experiments. It becomes even more important. However, some experimental instruments are not satisfactory. In recent years, the “self-induction demonstration instrument” assigned to our school by the teaching instrument station