Contact electrification and lichtenberg figures on insulators

Contact electrification experiments on insulators have been performed using liquid mercury as a compliant contacting electrode. The experiments show that large amounts of charge can be exchanged between the surfaces; in many cases the charge density is so large that air breakdown occurs when the surfaces are separated. The resulting charge distribution can then be “developed” by electrographic powders. The powder figures formed by developing these charge patterns strongly resemble the well-known Lichtenberg figures reported for discharges over insulators.
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