Sonoluminescence Help: Questions on Resistor Wattage, Coil Winding & Audio Amp

[AhmedA]

Sonoluminescence Help!

Hello everyone!

Working on my sonoluminescence project in the University of Washington, I encountered some (frustrating) issues. I have little/no electronic experience so please bear with me. Any help is appreciated.

First, looking at the images below, can anyone tell me what is the wattage specification for the resistor? suppose 30 watts are coming from the audio amplifier.

Second, I need a coil wrapped around a plastic spool with a ferrite core to adjust the inductance. How many turns of wire do I need? Whats the equation for this calculation? I'm using a spool with a 2 cm diameter and 2 cm length. My ferrite rod has a permeability of 600 and has an A_L value of 74 (the website mentions that is the nH/Square Turn or nH/N2)


Lastly, where can I order an appropriate amplifier? The lab I'm working in does not seem to have an audio amplifier. I need something that is not crazy expensive but will still achieve my needs in this experiment.

Thanks!
Ahmed A.


P.S: This the main reference article I'm using: http://techmind.org/sl/

 

[Bobbywhy]

Ahmed A. Welcome to Physics Forums!

As for the current sense resistor wattage, my guess is 10 Watts should be sufficient.

According to the instructions at the bottom of the techmid.org website you mentioned, the inductor specification is: "around 30mH. Partially-used 500g spool of 0.5mm diameter enamelled copper wire, tuned by sliding a ferrite rod up and down the centre of the plastic spool." You can see the two other DIY experiments below to find the inductor specifications they recommend.

As for the audio amplifier, most anyone will do, you'll need around 30 Watts output power, and you should verify the piezo drive signals are not distorted. They should look like clean, pure sine waves to drive your elements efficiently.

There are several other websites that describe this same experiment with all the details, parts, and procedures. Maybe if you study all of them you can make your experiment better. Here are two:

http://www.macgeisler.de/nld/sbsl-howto.html
http://www.webcitation.org/query?ur.../hbomb41ca/sono.html&date=2009-10-25+23:46:32

Here is one of the best articles on sonoluminescence ever written by two pioneers at UCLA:

“Producing Light from a Bubble of Air.” By R. A. Hiller, B. P. Barber.
Scientific American, February 1995
http://www.physics.ucla.edu/Sonoluminescence/sono.pdf

In that same magazine the authors published how to do the same experiment you are doing in great detail. Too bad I cannot find the article at no cost for you! I suggest you go to your library and copy this for reference!

The Amateur Scientist
Scientific American 272, 96 - 98 (1995)
doi:10.1038/scientificamerican0295-96
Producing Light from a Bubble of Air
Robert A. Hiller & Bradley P. Barber

Some experiments and mathematical descriptions:

http://www.pa.msu.edu/courses/PHY451/Experiments/sonoluminescence/SL%20experiments.pdf
http://en.wikipedia.org/wiki/User:Aolzick/sandbox

Some members here will be interested to hear from you about the results you achieve. Let us know!

 

[Carl Pugh]

Word of caution, consumer audio amplifiers are rated for momentary wattage.
If you order a consumer audio amplifier, for 30 watts continuous, you will require something like a 150 watt amplifier.
Industrial audio amplifiers are rated for continuous wattage, so for 30 watt you will require a 30 watt amplifier or larger.

Also if you use a wire wound resistor for sense resistor, it should be noninductive. A standard wire wound resistor will cause problems.