Spontaneous Separation of Charged Grains

(1) Sand grains (“art sand”), some of them blue and some red, sitting in a hopper. (2) The blue and red grains spontaneously separate when they are shaken and fall into a waiting beaker below. (3) Both the red and blue grains are positively charged, and while they sit on a surface, the mutual repulsion of the grains can propel some of them as high as 2 meters into the air.

Reported by: Troy Shinbrot’s group at Rutgers, publishing in Phys Rev Lett (Mehrotra et al.)

Associated Physics News Update 832, item 2

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