How To do

Today we bring a very easy experiment. It is an experiment very simple to at home realise without danger some for kids, in easy and funny form.


  • Dust pepper.
  • Liquid soap.
  • A deep plate.
  • Water
  • What is necessary to do?

    The first that we must do is to throw water in a deep plate, sufficient thing so that it covers the bottom. Next, we dusted a little pepper by all the surface.

    In order to obtain that the pepper “flees quickly”, the only thing that we must do is to place a liquid soap droplet in a finger and to just introduce it in center of the plate. As we can verify, the pepper hurries towards the ends of the plate, escaping of the afrhelp liquid soap.


    The pepper floats on the water because, although our eye does not see it, on her is a species of invisible layer that the subject one, what is called the surface tension of the water. The surface tension is a phenomenon in which the surface of a liquid, where the liquid is in touch with a gas, acts as a thin elastic lamina. This term is used typically only when the surface of the liquid is in touch with the gas (as the air). If the surface is between two liquids (as the water and the oil), interface tension is denominated “”. When soap is placed - that is a tensioactive element, meaning that breaks that attraction between molecules of the water. Consequently, the pepper does not have where to maintain and part it falls to the bottom and it starts off moves towards the edges of the plate.

    In the margins of the rivers insects live some, raw calls (Gerris natans), that walk with their long legs by the surface of the water without sinking. This ability explains by the surface tension, property of a liquid that causes that it behaves as if its surface was locked up in an elastic lamina. The surface tension also is responsible for the formation of the drops of rain, the soap bubbles or the elevation of liquids by a capillary.

    Explanatory video

    Video that explains the surface tension

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