CRAZY EFFECT OF LIQUIDS…(Leidenfrost)

This is a crazy yet interesting effect of liquids.

Now, when a liquid droplet is dropped on a hot surface the water droplet evaporates instantly. We usually expect the same in case of a surface with more temperature than the boiling point of the liquid, but it isn’t happening. The liquid droplet hovers over the hot surface. This strange phenomenon is first discovered by a German physician, Johann Gottod Leidenfrost.

How this happens?

WaterDropOnHotPlate

Initially we see the droplets move around before they evaporate, after a while, we see the droplets skitter around the pan randomly. This happens when the temperature of the bottom surface exceeds LEIDENFROST point. When this point is reached the bottom surface of the water droplet evaporates very instantly that it creates a little insulating pocket under the drop through which the droplet hovers. As the droplet moves around on the hot surface molecules of the water start turning into vapour.

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Here’s still interesting thing, if a droplet is introduced on an incline of finely milled grooves live tiny stairs, the grooves will create just the right disruption in the vapour to move the droplet up the stairs (grooves).

This crazy effect of liquids have application in micro cooling electronics, ink jet etc..

Thanks to my friend Prathik for suggesting this topic..

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