Chladni patterns in vibrated plates


Chladni patterns are a classic undergraduate demonstration. You can visualize the nodal lines of a vibrating elastic plate by sprinkling sand on it: the sand is thrown off the moving regions and piles up at the nodes. Normally, the plate is set vibrating by bowing it like a violin. It helps to put your fingers on the edge to select the mode you want, much like fingering the strings of a violin. This takes some practice.

You can make a nice modernized version of this demonstration using an electromagentic shaker (essentially a powerful speaker).

Chladni plate apparatus, schematic

With this you can vibrate much larger plates to much higher and purer modes. The shape of the plate is important. The usual demonstrations are round and square plates. Here are some sample patterns: all the plates were 0.125 inch thick Aluminum, painted black.

A more interesting shape is a stadium: a square with rounded endcaps.

Finally, getting back to our musical roots, we built a plate in the shape of a large violin. Here are some patterns:


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The Experimental Nonlinear Physics Group, Dept. of Physics, University of Toronto,
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