The droplets of water begin to dance when poured on a hot plate because when a water droplet which is at room temperature falls on a hot plate which is at 150-200 degree Celsius a layer of steam to form. This layer of steam which then connects to the drop of water and the plate starts acting as a cushion. Then after coming to the bottom layer of water starts heating. The water in the drop gets heated to more than 100-degree centigrade. This leads to the formation of steam at the interface.
The plate’s heat does not get easily transferred or get flowed into the drop because steam is not a good conductor of heat. Because of this, the temperature usually falls down as we move up from the interface.
The steam which is immediately above the layer is called boiling water. There is a zone which is called free convention zone which is present in the outer layer gets heated slightly. So, whenever water tries to rest on the plate, steam starts acting like a cushion.
Sometimes, when steam leaks out water fills that gap and then gets vaporized. This process of heating and cooling continues until the water gets completely vaporized.
So, a water droplet dance on a hot plate because when hot water is poured on the plate a cushion is formed in the form of steam which is a bad conductor of heat which does not allow the heat to flow anywhere else.
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