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在高中的机械波教学中,水波干涉实验是个必做的重要演示实验,采用的又多是投影观察法。在引导学生观察水波干涉现象时,合振动的加强区和减弱区是通过投射在屋顶或屏幕上的明暗条纹来观察的,但教师对明暗条纹产生的原因的解释又多有错误,下面对此问题进行讨论。1 水层厚薄说这是在中学教师中比较流行,学生又比较容易接受的一种说法。某杂志1995年1期中的《看得穿.才能识得透》一文中是这样解释的:波谷处出现“明条纹”的原因是什么(水层薄、透射光强度大)?波峰处出现“暗条纹”的原因是什么(水层厚、透射光强
In the high school mechanical wave teaching, the water wave interference experiment is an important demonstration experiment that must be done, and most of it is the projection observation method. In guiding students to observe water wave interference, the reinforced and weakened areas of the combined vibration are observed through bright and dark stripes projected on the roof or on the screen. However, the teachers’ explanations of the causes of light and dark stripes are often wrong. This issue is discussed. 1 The thickness of the water layer says that this is more popular among middle school teachers and students are more easily accepted. This is explained in the article “Let’s See It Through.” in a magazine in the first issue of 1995. What is the reason for the appearance of “bright stripe” at the trough (the water layer is thin and the transmitted light intensity is high)? What are the reasons for the appearance of “dark streaks” (thickness of the water layer and transmitted light intensity