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Dancing water on a hot pan - here's why?


Ever wondered why water droplets suddenly start dancing on a hot pan, while they simmer away most of the times.  As if they have a mind of their own, water droplets seem to act like this in a random fashion. Well, you are not the first one to have observed this or to have dismissed it as an random act. In the year 1796, Johann Leidenfrost, found some order in this randomness, which is now known as the Leidenfrost effect.

Image from Wikipedia
Initially, as a hot pan reaches the boiling point of water, water evaporates slowly. As temperature increases and goes beyond 100 degrees Celsius, water evaporates immediately, usually accompanied with a hissing sound. As the temperature is increased further, water continues to evaporate quickly, except that the water closest to pan heats up quicker, evaporates and makes a small cushion of vapour between the pan and water droplet. Since, vapour conducts heat poorly, heat from the pan takes much longer to reach and completely evaporate the water droplet that is hanging above the vapour cushion.

Researchers at the University of Bath, recently used this phenomenon, to make a superheated maze. What is even better is that they a made a video out of this for all to see.  Who wouldn't want to do something like this at work?





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