Re: Do you know anything about this activitiy?

[trappe@PHYSICS.UTEXAS.EDU (Karl Trappe)]

I call this demo "Moses and the burning bush" for obvious reasons.  I
constructed it about 1963 when I was an undergraduate, but stole the idea
from a Popular Electronics article of the same era.  I just decided that I
would be struck by lightning for blasphemy if I named it appropriately.

It takes a very high power amplifier which is capable of running
Electrostatic Loud Speakers (ESLU's)   You connect the output to two carbon
rods which are then subjected to the flame.  If these rods are connected to
the output of the high gain/high wattage amplifier, the flame will respond
according to the excitation. If the carbon rods don't work immediately, you
can add *salts* to them to make the flame conduct.

Now the closest demonstrations to this that I now do are called Jacobs
ladder, and conductivity of glass.  In both, a very high voltage arcs
across the bunsen burner flame making a noise like Zzzttt, or something
like that.  Obviously, if a flame can make a noise and you can modulate the
voltage, you can make the flame talk to you or sing.  Being a wiseass, I
thought instantly of making the flame in the form of a bush and having a
voice speak to students who wlked by...but then I kept worrying about the
bolt of lightning!  Smile, Karl

> Please help
>
> Can anyone help us out?  I think I see the principles but want for more
> details.
>
> Thanks in advance.
> Sheron Snyder
> ************************************
> > Hi Sharon,
> >
> > I got the following e-mail and I have no clue what this experiment is
> > all about:
> >
> > > My name is Eric Arnold, I am a senior in high school, and I'm
> > > taking AP physics. We have to do a semester project on anything physics
> > > related. I asked my dad for an idea and he said that when he was a kid he
> > > made a speaker out of a flame. He couldn't remember all the details, but
> > > thought it involved putting a string soaked in salt water in the flame,
> > > and then putting the ends of a speaker wire in the flame. If you know how
> > > to do this, or have an idea of where to look, who to ask, I would greatly
> > > appreciate it.
> >
> > Have you ever seen/done/heard about the above project? I don't know what
> > salt water does to string and why the string would not burn at some point.
> >   Thanks
>
>
> Sheron Snyder, Outreach Coordinator
> Physics and Astronomy,  Abrams Planetarium
> National Superconducting Cyclotron Laboratory
> Fax:517-432-3838
>
> "In nature there are neither rewards nor punishments.  There are
> consequences."
> Robert G. Ingersoll

Dr. Karl I. Trappe                              Desk Phone:  (512) 471-4152
Physics Dept, Mail Stop C-1600                  Demo Office: (512) 471-5411
The University of Texas at Austin               Home Phone:  (512) 264-1616
Austin, Texas 78712-1081