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初中物理第二册第38页的双金属片实验是用如下方法做的:把长和宽都相同的铜片和铁片紧紧地铆在一起,做成双金属片。用酒精灯给双金属片的铁片加热,双金属片就向下(铁片)弯曲,这表明当同样受热时,铜片膨胀得比铁片大。该实验不足之处是,有的学生可能会认为:双金属片向下弯曲是因为双金属片被烧软,双金属片在重力的作用下向下垂的缘故。
The bimetal experiment on the 38th page of the second book of junior high school physics is done by the following method: The copper and iron pieces with the same length and width are tightly riveted together to form a bimetal. Using an alcohol lamp to heat the iron plate of the bimetal, the bimetal is bent downward (iron plate), which means that when the same heat is applied, the copper plate expands more than the iron plate. The inadequacy of this experiment is that some students may think that the bimetal is bent downwards because the bimetal is burned and the bimetal is drooping under the influence of gravity.