Thursday, June 21, 2007

Chladni Patterns


Chladni day is held on June 29th in Massachusetts, Maine and Puerto Rico, so we are preparing here for the event in the usual way, looking at Chladni patterns produced by sand spread over metal plates that are bowed with a violin bow. Here they are for your enjoyment too. Note that in these examples, all squares, many right angle modes are supported. Of course there are three, not two dimensions at work here, and the orthogonal modes are as much an indication of lateral and axial motion, together, at work to produce the complex and surprising nodes and antinodes seen here. On a guitar body, for instance, the patterns are much more complex. Even a circle can produce complex patterns, and "break up" at the higher overtones to produce up and down motion simultaneously, leading to comb effects in certain microphones that are not design to suppress Chladni action.

But we are celebrating, not suppressing Chladni, at least not next week. Chladni was an important scientist who, among many other things, was the first to convince the scientific community of the the time that meteorites are of extraterrestrial origin. That was important.

Great fun with Chladni! Click on this link to develop your own Chladni patterns using circles or rectangles.

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