题干

小红同学认真观察了家里烧开水的过程,发现当水沸腾时,壶嘴口不断有“白气”出现时;但通过进一步的仔细观察却发现出现“白气”的位置总是与壶嘴口有一小段距离,在壶嘴位置却几乎看不见“白气”.请你用所学的物理知识解释这一现象.

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答案(点此获取答案解析)

解:在离壶嘴一小段距离的位置不断有“白气”出现,是由于水蒸气遇到冷的空气液化成小水珠;在水壶口处什么也看不见,是由于水壶口处的温度比较高,喷出的水蒸气不能放热液化。

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