Amazing Resonance Experiment

Drazen

Drazen

Jedi Council Member
FOTCM Member
This is the Chladni plate experiment. A tone generator, a wave driver (speaker) and a metal plate attached to the speaker are used. First add sand to the plate then begin playing a tone. Certain frequencies vibrate the metal plate in such a way that it creates areas where there is no vibration. The sand "falls" into those areas, creating beautiful geometric patterns. As the frequency increases in pitch the patterns become more complex.

http://www.youtube.com/watch?feature=player_embedded&v=wvJAgrUBF4w

and unedited version with tone throughout entire video:

WARNING: Please lower your volume.The audio in this clip could cause hearing damage.

http://www.youtube.com/watch?v=1yaqUI4b974
 
drazen said:
...and unedited version with tone throughout entire video:

WARNING: Please lower your volume.The audio in this clip could cause hearing damage.

http://www.youtube.com/watch?v=1yaqUI4b974
Click to expand...

That was amazing to watch. Made me wonder if this has something to do with the way real crop circles are created.
 
At the risk of sounding pedantic, this is not an experiment, but rather a demo, which is commonly used to teach about standing wave patterns in 2 dimensions at high school level of physics. Such standing waves have been known for the longest time; I remember seeing an article about aborigines tying a taut skin above a resonant cavity into which one would sing in short bursts; the resultant patterns in the sand sprinkled on the skin were used as inspiration for paintings.

Pushing this to the next level, electromagnetic standing waves can be demonstrated in 3 dimensions using ferrofluids, that is, viscous liquid holding ferromagnetic particles in suspension.

I'd suspect that crop circles are not the result of simple 2 dimensional vibratory standing waves (the patterns are too limited) but rather something like the projection of a cross-section of higher-dimensional standing waves such as those observed in ferrofluid.

Chladni plate patterns:
http://sharp.bu.edu/~slehar/webstuff/hr1/chlad.gif

Link to a nice ferrofluid demo:
http://www.youtube.com/watch?v=BTn2rtULhTI
 
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