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初中物理第二册第七章“电池”一节中“伏打电池”演示是学生比较感兴趣的内容,过去我们一直按课本上的方法进行演示,当做为电池的两个极锌板和铜板一起浸入稀硫酸溶液时(图1),外电路中的灯泡D只是瞬间出现微光.为增强演示效果我们将装置中的稀硫酸溶液改换成硫酸铜溶液效果就大有改观,灯泡D亮度强,持续发光时间可达30分钟(图2). 为什么在这个实验中改用硫酸铜溶液较之稀硫酸溶液效果好呢? 在原如图1
The “Voltacell” demonstration in the seventh chapter “Battery” in the second book of junior high school physics is more interesting for students. In the past, we have been demonstrating according to the textbook method, as the two pole plates and copper plates of the battery. When immersed in a dilute sulfuric acid solution (Figure 1), the light bulb D in the external circuit is only a momentary glimmer. To enhance the demonstration effect, we will change the dilute sulfuric acid solution in the device to a copper sulfate solution. The effect will be greatly improved. Strong, sustained luminous time of up to 30 minutes (Figure 2). Why is it better to use a copper sulfate solution than a dilute sulfuric acid solution in this experiment?