A set of Chladni standing wave patterns generated in sand...

A set of Chladni standing wave patterns generated in sand on the surface of a vibrating metal plate.  The sand collects in the areas of the plate where the waves in the plate cancel each other completely.  Each resonant wave pattern occurs at a specific frequency.  This set was originally published by John Tyndall in 1869, it has been reorganized to show the periodic families that emerge as the frequency of the vibration increases.