Just by shaking sand grains, they segregate without outside influences

Jul 13, 2007 10:33 GMT  ·  By
Sand grains (?art sand?), some of them blue and some red, sitting in a hopper
2 photos
   Sand grains (?art sand?), some of them blue and some red, sitting in a hopper

Although they did not find out how Moses could separate the water of the Red Sea, they were able to do the same with a mass of sand grains, in an experiment which proves that no outside force is necessary to make identical molecules part.

Scientists at the Rutgers University, New Jersey, proved that two identical populations of sand that were mixed together in a hopper and then shaken into a beaker would spontaneously separate, with no outside intervention just because of static electrical interactions.

Troy Shinbrot and his colleagues were puzzled by the observation and they think this phenomenon could be exploited in many industry areas, leading to new applications in powder industry and possibly even in constructions.

The experiment consisted in mixing two types of sand, which are chemically and mechanically identical and were colored blue and red just for this purpose, without altering any of their properties. When they were shaken, they acquired different electric charges, in a process where some of them are thought to lose some electrons due to the jostling motion, thus becoming positively charged.

So far, the process is not fully understood, but experimental evidence showed that the blue and red grains did separate themselves in falling of the hopper platform, with no other reason than static electricity.

Another puzzling observation was the fact that the blue grains, positively charged, landed close to a van de Graaf generator, an electrostatic machine that was also positively charged. The problem is the same charge repulsion should have kept them away.

Yet another interesting effect was seen during the experiment, the fact that as both types of molecules sit on the hopper, the mutual repulsion of the grains can propel some of them as high as 2 meters into the air.

Further examinations of this effect need to be carried out so that scientists can better understand its causes, thus paving the way for its introduction into practical applications.

Photo Gallery (2 Images)

Sand grains (“art sand”), some of them blue and some red, sitting in a hopper
The blue and red grains spontaneously separate when they are shaken and fall into a waiting beaker below.
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