Re: Chladni figures...

[jriley@lib.drury.edu (Jim Riley)]

I have had great success in forming chladni figures on a brass plate, both
round and square clamped in the middle.  The square plate is slightly easier
to excite.  I use salt sprinkled on top to reveal the patterns and use an
old violin bow that has been in the department for decades.  Rosin on the
bow helps but is not entirely necessary.  The salt will corrode the brass
plate but its accessibility and visibility more than compensate for the
effort needed to clean the plate periodically.   The exact location of the
bow on the edge of the plate determines which pattern will form.  When using
a square plate try bowing in the middle of one edge with an upstroke.  It
does take some practice to consistently produce a tone.  

It may also be that your galvanized steel plate doesn't have the right
resonant frequencies to be easily excited by the bow.  The brass plate that
I use was acquired decades ago before I came here, probably from Cenco, is
about 0.02 inches thick and ten inches square.  You could probably get one
from a local metal supplier cheaper than from Cenco.  





> Greetings!  I was wondering if anyone has ever tried making chladni 
> figures as a lab or demo?  If so, could you give me some advice on doing 
> so?  What materials did you use?  What type of patterns did you get?  
> I've tried using a metal disk (galvanized sheet metal) supported at the 
> center and various "bows" to produce the sound vibrations.  I've been 
> unsuccessful and was wondering if there is anything else I could use that 
> is readily available.  Any help would be greatly appreciated.
>
> Thanks,
> Dwight
> dsouder@ashland.edu
Jim Riley, Department of Physics
Drury College
Springfield, MO 65802
e-mail: jriley@lib.drury.edu
Phone:  (407) 873 7233