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Is the electric force responsible for this phenomena?

  1. Nov 16, 2009 #1


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    I just used some species in a salsa for a couscous. The species were in powder form. When I put them in contact with the water of the salsa, they spread over a large part of the water' surface. It reminded me the electrons of a negatively charged conductor.
    Whatever was the spice, the effect took place.
    Is the electric force held responsible for such a behavior of little macroscopic particles? I know that the species are neutral but they could be somehow polarized, or not?
    I've already seen this phenomena in many other opportunities.
    I've also read the article http://www.scientificamerican.com/article.cfm?id=particle-dispersion-liquid but I don't understand it well.
    What I understand from it is that the powder reduces water surface and thus the energy of the water decreases (why?), implying an increase of energy in the small macroscopic particles (*). Fine but shouldn't they spread slowly despite their fast velocities? Like when one opens a perfume, the smell being "fast" molecules takes time to reach a 1 meter distance because of the Brownian motion or so. (I'm not an expert on this, I might be wrong).

    (*) But why doesn't the powder make pressure on water an increase the temperature of water, thus increasing the internal energy of water instead of decreasing it?

    I'm confused.
  2. jcsd
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