From: Mark Lawton (markslawton@hotmail.com)
Date: Sun May 18 2003 - 10:18:19 PDT
Date: Sun, 18 May 2003 10:18:19 -0700 Subject: Re: Pinhole Digest #1219 - 05/18/03 From: Mark Lawton <markslawton@hotmail.com> Message-ID: <BAED0E6B.3D26%markslawton@hotmail.com>
steve,
with the tube sealed at one end with water and open at the other end you
should get resonance at:
.25 * Lambda
.75 * lambda
1.25 * lamda
etc.
the pattern needs a node at the closed end and an anti-node at the open end
good pics are available in the giancolli book
-mark Lawton
> From: "Pinhole Listserv" <pinhole@exploratorium.edu>
> Date: Sun, 18 May 2003 00:20:01 -0700
> To: "Pinhole Listserv" <pinhole@exploratorium.edu>
> Subject: Pinhole Digest #1219 - 05/18/03
>
> Pinhole Digest #1219 - Sunday, May 18, 2003
>
> variations on frequency
> by "Steve Miller" <nanodog2@hotmail.com>
>
>
> ----------------------------------------------------------------------
>
> Subject: variations on frequency
> From: "Steve Miller" <nanodog2@hotmail.com>
> Date: Sat, 17 May 2003 11:01:32 -0700
>
> In Hewitt's lab book there is a great lab on finding the speed of sound by
> using a tuning fork that is held just above a 50 cm piece of pvc that is in
> water. They use a one liter graduated cylinder. You hit the tuning fork and
> raise the pipe until a distinct ringing is heard. This length is 1/4 the
> wavelength. That length, plus the frequency of the tuning fork, allows you
> to find the speed of sound.
>
> The 1/4 length is where the air column resonates. I presume that iff you had
> a longer piece of pvc, you would find resonance again at 1/2 the wave
> length.
>
> I have been playing around with this. This is my best thinking so far. I
> would really appreciate any corrections or advice. Is the thinking
> correct???!???
>
> I have been trying this with 9th graders. Use the same set up. Use different
> length PVC pipes. Blow over the end to make a tone. The tone occurs at any
> length. By raising the tube, the tone goes down. However I presume that
> sooner or later you will come to a point where the air column is truly
> resonating.
> By playing around with this, it seems that when you reach a point of
> resonance you hear a much more resonant tone - and - you can really feel the
> graduated cylinder (and the water) vibrating. This does not occur so
> dramatically at other lengths.
>
> So my questions: Are these steps correct? Can you really find a resonance
> point this way?
>
> Assuming you can, you could use the simple formula "velocity = wavelength
> x frequency" to find the frequency of each tone at the resonance point.
> This really works great in getting them to grasp the formula, and privides
> practice in finding experimental calculations.
>
> However, the next question: Assuming once again that you do hit the
> resonance point, what part of the wavelength is it? Is it half the wave
> length or one fourth? Or is it something else?
>
> Steve Miller
>
> _________________________________________________________________
> Protect your PC - get McAfee.com VirusScan Online
> http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
>
>
> ----------------------------------------------------------------------
> End of Pinhole Digest
>
> ---------------------------------------------------------------------------
> To unsubscribe from pinhole, send an email to requests@exploratorium.edu
> with the words 'unsubscribe pinhole' (without the quotes) in the SUBJECT of
> the email.
>
> To subscribe to the digest and only get 1 combined message a day, send an
> email to requests@exploratorium.edu with the words 'subscribe digest pinhole'
> (without the quotes) in the SUBJECT of the email.
>
> Check out what your colleagues have written on Pinhole in the Pinhole archives
> at: http://saturn.exploratorium.edu/ti/alumni/pinhole.html
> ---------------------------------------------------------------------------
>
>
This archive was generated by hypermail 2.1.3 : Mon Aug 04 2003 - 16:18:13 PDT