If you need to stock up on sugru, you can buy it here and also from the Instructables store. I don't need to destroy my nice speaker since I can cut sugru and re-use my speaker once the experiment is done You have time to make the whole set-up level before the sugru curesĬan also create custom-made dampening pads for the contact with the table the rig sits on. The Foundation’s homepage may be found here, and its Youtube channel, florencefst, here.It provides a great acoustic contact that bonds to plastic sheet, board, metal, glassĬreates a perfect seal between the speaker and the plate The Foundation for Science and Technics, or Fondazione Scienza e Tecnica, of Florence, Italy, has made available many videos exploring the Cabinet of Physics, a large collection of antique scientific demonstration instruments. It’s a startling idea, but as evidence was gathered over the next few decades, other scientists came to accept that Chladni was correct.
Chladni argued in 1794 that certain iron-rich minerals we now know as meteorites might originate beyond the Earth. Normally the processes that create sound occur invisibly, but in this demonstration, something about sound has become visible.īy the way, Ernst Chladni is renowned for his contribution to acoustics, but he might be familiar to the scientists of the Vatican Observatory for a different reason. Even a paper membrane, not touched by the bow but excited only by sound passing through the air, exhibits its own Chladni pattern. Different shapes and sizes of plate also yield different Chladni figures. If the strokes of the bow excite a different resonance, making a higher note, the Chladni figure changes as the sand grains rearrange themselves along the new nodes. These patterns are named for Ernst Chladni (1756-1827). The spiky patterns of sand reveal the special geometry that’s connected to that tone. If it lands on a location that is scarcely moving, it will remain there, safe from further jiggling.īy this process, grains of sand tend to accumulate in the special locations or “nodes” that are not moving as the plate continues to vibrate with a particular tone.
A sand grain that lands on a rapidly-moving portion of the plate will be jiggled, and will bounce to another location, perhaps to be bounced again. We see pale sand being sprinkled onto the dark plates. When stroked to produce a tone, some parts of the plate move more than others. In today’s video, it is more effective to stroke a plate with a violin bow. An object like this can be persuaded to make a sound-one might thwack it with a spoon, perhaps, and hear it chime. Out of the Cabinet of Physics come brass plates, of various shapes and sizes, each supported on a single leg at its center. Here is an example from the field of acoustics. I enjoy the sort of scientific demonstrations we might call “illustrations:” they make visible something about sound, or heat, or motion that would otherwise pass unseen.
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