找一块玻璃板,放在水里浸一下,然后一头放在桌上,另一头用几本书垫起来(高度5~6厘米)。将一只玻璃杯,杯口沾些水,倒扣在玻璃板上。这时,手拿点着的蜡烛去熏烧杯子的底部,你就会惊奇地发现:咦!玻璃杯竟会自己往下走去。这是怎么回事呢?原来,当烛火熏烧杯底的时候,杯内的空气渐渐受热膨胀,要往外挤。但是,杯口是倒扣着的,又有一层水将杯口封闭,热空气跑不 Find a piece of glass, dip it in water, put it on the table, and pad it with several books (height 5 to 6 cm). Will be a glass, cup mouth with some water, inverted buckle on the glass. At this moment, with a candle in your hand to smother the bottom of the cup, you will be surprised to find out: 咦! The glass will actually walk down. This is how the case? It turned out that when the candle fumigation bottom of the cup, the cup of air gradually heat expansion, to squeeze out. However, the cup is inverted with a cup of water, another layer of water will cup closed, hot air does not run