Date: Mon Dec 1 18:52:47 2008

Author: Marc \ Zeke\" Kossover"

Subject: Re: Resonance Tube, The Old vs. The New

Post:

I use a somewhat simpler design. I bought two sets of Boomwhackers from Arbor Scientific . Then I rolled a transparency the long direction and slipped it inside the Boomwhacker tube and let it expand so that it fit snugly in the tube. I taped the transparency so that it would stay in shape but could still be slid in and out of the tube to change it's length. It's child's play to measure the length of the tube and the slid out transparency with a meter stick, but if you are so inclined, you can print a ruler on the transparency and mark on the Boomwhacker its length.

The resonance are loud and distinct with tuning forks even with six lab groups going. For fun, you can get physicist tuning forks (middle C is 256 Hz) and well-tempered tuning forks (middle C is 261.2 Hz) to show that close isn't the same as being right on.

Marc "Zeke" Kossover


________________________________
From: Dan Bernoulli
To: tap-l@lists.ncsu.edu
Sent: Sunday, November 30, 2008 8:12:36 PM
Subject: Re: [tap-l] Resonance Tube, The Old vs. The New

Carchng up on list communications. Here's my 2 bits worth on resonance tubes.

We finally abandoned our water filled resonance tubes when we could not get the glass tube replacements. The new apparatus with plastic tubes did not work as well, the sound at resonance was not as large, the scales were too short and the tubes tended to break. At nearly $100 apiece that was the straw that broke the camel's back.

After too many failed attempts we finally just built some apparati out of polycarbonate tubes. The tubes sit on (extruded tubing) aluminum pedastals. We use a piston made of plastic. The piston is moved with a string which is attached to both ends of the piston by screws. Scales were stick-on scales first purchased through McMaster Carr or Msc, don't remember which. After finishing the prototype we purchased the scales directly from the manufacturer. We have noticed the resonances do not sound as loud as on the old glass apparatus. Although I have not verified it, I believe one reason the resonances
are not as loud is because the plastic tubes are slightly smaller in
diameter than the glass tubes. Another is the vertical glass tubes radiate into almost a whole space while our horizontal units often sit in the middle of the lab table so they radiate into a half space, sort of. When the end is dangled over the table edge they work better. We are quite satisified with them. We've been using the apparatus about a year now and have had absolutely no problems. The apparatus is light, simple to construct, easy to use and easy to maintain. They are compact and totally easy to store. Best of all, no more puddles of water in the lab, no more kinked hoses, no more glass shards on the floor etc..

While we were making the tubes, we also investigated new tuning forks. One of our faculy's siblings did a project on sound resonance and had real trouble with loadspeakers and electronics in finding resonances (the speaker resonance were in the same range as the tube resonaces) so I tend to shy away from electronics. Also i couldn't find any what I consider decent forks, most were lighter than our old forks and didn't resonate nearly as long (like the 50 year old big handled forks with the bakelite handles) so we made our own. I am fortunate to have a good shop that knows how to do such things.

Personally I ike using tuning forks over speakers and oscilloscopes. It seems like everytime we put a little technology into a lab it becomdes an excuse for failure. I would rather spend the time that would otherwise be spent teaching buttons and knobs on end and pipe diameter corrections.

I miss the old apparatti but one must move on.

Dan Beeker
Indiana University


> From: bnorwood@umd.edu
> To: tap-l@lists.ncsu.edu
> Subject: [tap-l] Resonance Tube, The Old vs. The New
> Date: Tue, 25 Nov 2008 13:00:45 -0500
>
> Jerry, Is the WA-9212 a really good experiment for the survey course type
> students? Is it far superior to the old whacking a tuning fork and changing
> the water level in a vertical tube until one gets resonance? Just becoming a
> little "worried" about our sound lab possibly going out of date. Thanks for
> any perspective, Bill Norwood, U of MD at College Park
>
> -----Original Message-----
> From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
> Behalf Of Jerry DiMarco
> Sent: Tuesday, November 25, 2008 12:46 PM
> To: tap-l@lists.ncsu.edu
> Subject: Re: [tap-l] Sound Generator and Resonance Tube
>
> George,
>
> One of our setups is Pasco's WA-9612 resonance tube. You can see it
> here:
>
> l=1>
>
> Come to think of it, it is difficult to hear resonances in it too, but it
> is used with a mic inside the tube which connects to an oscilloscope. The
> other arrangement is various cardboard tubes with a small Radio Shack cube
> speaker, about 10 cm on a side. One tube is ~15 cm OD, the other is ~8
> cm. In both, the first harmonic is much more apparent than the fundamental
> (listening from the other end). The signal gen is an older model Pasco,
> PI-9587A...
>
>
> Jerry
>
>
> At 11/25/2008 09:54 AM, you wrote:
> >Jerry:
> >Thanks for the reply.
> >The speaker is on the back of the sound generator, i.e. it is on the "flip
> >side" from the side with the pushbuttons and LEDs.
> >I'll measure the diameter of the opening (which is about the same as the
> >dia. of the speaker) and let you know what that is.
> >Meanwhile, what type and dia. of speakers do you use? What dia. is the
> >tube that you use? And (while we're at it), what kind of oscillator (not
> >that that should matter)?
> >
> >Thanks.
> >
> >George
>
>
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
>
> Jerry DiMarco
> Manager of Lecture Demonstrations and Instructional Labs
> Montana State Univ., Physics Dept.
>
> Bozeman, MT
>
> Our Motto: "Find your inner demo."
>
>

________________________________
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