AboutDan Fink Expertise Though my experience is mostly in the fields of electricity, magnetism, and physics, I have a broad science background. My career is in the field of alternative power sources -- solar, wind, water and battery power. But any questions about electricity, magnetism, energy conservation, power generation, electric motors, and even general physics are very welcome--especially from kids. They ask the best questions of all! I pride myself in answering science questions accurately, with ideas for SAFE, easy experiments that kids can perform by themselves--and that let them prove the answers to their own satisfaction. I think science should be fun, and available to everyone, regardless of age.
Experience I have volunteered in our local public schools for 5 years. I currently make presentations at our schools about electricity and magnetism, with a focus on solar, wind, water and other alternative power sources. I try to demonstrate at our schools how easy it is to make electricity, with simple devices using spinning magnets and coils of wire--powered by wind, water, bicycles, gerbils...etc. And of course solar panels! I am the webmaster of Otherpower.com, an alternative energy website. I have lived 10 miles from the nearest power pole for 11 years--I make all my own electricity from scratch with sun, wind and water.
Publications Otherpower.com
Wondermagnet.com
Co author of the book "Homebrew Wind Power" ISBN 978-0-9819201-0-8
My articles appear regularly in such magazines as Home Power and Back Home Education/Credentials BA Technical Journalism
Question hey i've been doing research on Thermoaucustic Refrigeration, which is the process of using sound waves to chill food and things. im wondering if you have any ideas of any expirements or demonstrations i could do on this topic??? thanx!
Answer An extremely interesting subject! Here at my office we've always had fun working on home experiments that demonstrate complicated concepts....but this one looks hard to replicate at home. I think your best bet is to use diagrams and math to show how acoustic refrigeration works...it sounds like you've already Googled the topic.
I could only find one reference to a small scale system--in a master's thesis you'd have to buy: http://www.stormingmedia.us/14/1490/A149093.html
It still uses some custom, complicated equipment.
I think to reproduce this experiment with any chance of success you'd need access to a University physics and chemistry laboratory. Here's why....
The main problem with a home experiment is that the concept only works effectively in a chamber filled with a pressurized noble gas. The speakers would have to have huge amplifiers, or be specially designed to work efficiently at only one frequency....big time complicated engineering for both these problems. And your heat sink would have to be extremely efficent and placed precisely at the right spot in a tube.
But, perhaps you could show *part* of the concept in an experiment.....the key factor is making the sound waves from a speaker bounce off the other end of a tube and meet exactly in the middle. Thermoacoustic refrigeration works by taking the increase in pressure at this precise spot and sinking the extra heat away. You'd need to calculate sound wavelengths and reflection time (speed of sound at a particular air density and temperature) and figure out precisely where to position a decibel meter inside the tube...if you were able to get it in exactly the right spot, your decibel meter should show a dramatic increase in sound intensity where the new sound waves meet the reflected ones. I don't have any specific ideas as to how to do this....perhaps you could take apart a decibel meter from radioshack and hang the sensor in the tube. And you'd need a frequency generator and counter to drive the speaker, since you'd have to preceisely dial in the correct frequency to make it work.
I hope this helps -- it's about as close as I can come to a home experiment! Hmmm, perhaps you could set a loudspeaker playing a single frequency pointed at a bare wall, and find the spot in the middle where the bounced waves meet the new ones? It should sound louder to you at that spot. You'd still have to have an adjustable frequency generator to tune it in right....
You have your work cut out for you here.....you can always punt and just do the math and diagrams. The Los Alamos site has some interactive online tools to visualize the concept.
