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Re: Singing pipes



Richard W. Tarara wrote:

From the vast amount of traffic on this topic, it seems clear that many do
this demo, but from the lack of a coherent explanation (or the complexity
of such explanations) I fail to see the pedagogical value. Only George
Spagna's lab seems to make any real 'use' of the phenomenon. This seems to
me to be one of the many 'gee whiz' demos that we often get into but that
fail to educate in proportion to the time, effort, and expense invested in
them.

I think it is a wonderful demo to use in conjunction with the
introductory treatment of resonance where I assume most of us discuss
all kinds of devices illustrating the effect -- from waves on strings to
pianos to organ pipes to reed instruments to brass instruments to the
Tacoma Narrows bridge. I'm not sure I could explain the details of how
blowing across the top of a bottle creates a sound ... but I still do it
and discuss it. The singing pipes are nice because students get to see
that you don't have to do anything fancy to get some pretty amazing
sounds. I learned at an AAPT meeting years ago to have students take
the same pipes and hold them up to their ears to "freqeuncy select"
resonant sounds from the "white sound" all around us. With different
sized pipes, it is as clear a demonstration as any of the relationship
of size of the resonant cavity to wavelength and frequency -- a lot of
learning there.

Cheers,

Rick

--
Richard E. Swanson, Ph.D. (910) 695-3715
Professor of Physics FAX: (910) 695-1823
Associate Dean for Development and Technology
swansonr@sandpiper.sandhills.cc.nc.us
Sandhills Community College
Pinehurst, North Carolina 28374 "He who laughs, lasts."