The temperature of the surface is so hot that water droplets bounce and dance.


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Theory 

Since the hot plate is is held at a temperature much higher than the boiling point of water, the droplets boil instantly when they fall. A small layer of steam forms in between the droplet and the plate resulting in motion similar to that of a hovercraft. The droplet can "skate" around on this cushion of steam for some time before it completely boils off. This effect only happens when a surface exceeds the boiling point of a liquid by a large amount.


Apparatus 
  • hot plate
  • cup of water
  • large pyrex beaker of water

Procedure
  • Place the large pyrex beaker of water onto the hot plate.  The beaker will help to regulate the temperature of the hot plate.
  • Turn on the plate and heat it up as you would to bring the beaker to a near-boil.
  • Drip some water carefully onto an exposed area of the plate.  If the temperature is hot enough, the water droplets should dance about.

Safety 
  • Be very careful using water around electrical devices.  
  • Drip the water onto the plate is VERY small amounts.  Too much water can lead to the water "exploding", potentially burning your hands or face.
  • Be careful to protect yourself against burns from the produced steam.