Monday, January 19, 2009

Lichtenberg Figures

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Lichtenberg Figures are branching electric discharges (or electrical trees) that are sometimes preserved on the surface or the interior of a solid dielectric. They are named after the German physicist Georg Christoph Lichtenberg, who originally discovered and studied them.



One way that they can be produced is as follows: A sharp-pointed needle is placed perpendicular to a non-conducting plate, such as of resin, ebonite, or glass, with its point very near to or in contact with the plate, and a high voltage Leyden jar (a type of capacitor) or a static electricity generator is discharged into the needle. The electrification of the plate is now tested by sifting over it a mixture of powdered flowers of sulfur and red lead (Pb3O4 or lead tetroxide).




The negatively electrified sulfur is seen to attach itself to the positively electrified parts of the plate, and the positively electrified red lead to the negatively electrified parts. In addition to the distribution of color thereby produced, there is a marked difference in the form of the figure, according to the polarity of the electrical charge that was applied to the plate. If the charge was positive, a widely extending patch is seen on the plate, consisting of a dense nucleus, from which branches radiate in all directions; if negative, the patch is much smaller and has a sharp circular boundary entirely devoid of branches.









You can read more about Lichtenberg Figures HERE.

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