<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div> Graham,<div><br></div><div>I too had been asked this question a while ago, but as I didn't know and I didn't have one I forgot all about it.</div><div><br></div><div>The following website, if correct, says you are right or wrong depending on the pressure itself:</div><div><br></div><div><a href="http://www.fysikbasen.dk/English.php?page=Vis&id=6">http://www.fysikbasen.dk/English.php?page=Vis&id=6</a></div><div><br></div><div>At the bottom of the article are some references -sadly the one that looks most likely to explain the answer in detail is on the aapt site and as I am not a member, I can't read it!</div><div><br></div><div>Sorry</div><div><br></div><div><br><div> <span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="">David King</div><div style="">Physics HoD</div><div style="">Christ's College</div><div style="">Private Bag 4900</div><div style="">Christchurch</div><div style="">New Zealand</div><div style="font-size: 12px; "><br class="khtml-block-placeholder"></div><div style="font-size: 12px; "><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span> </div><br><div><div>On 18/06/2008, at 6:40 PM, <a href="mailto:g.foster@clear.net.nz">g.foster@clear.net.nz</a> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Greetings Fellow Physies</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">We have just made a long metallic tube with a loud speaker</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">at one end and gas entry at the other. This enables us to</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">light the gas which comes through 1 mm holes 1.0 cm apart</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">and to produce single frequency sound at the other. The</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">flame pattern at resonance is one where we see high flames</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">at the antinodes and small flames at the nodes. Many of you</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">will have seen similar appartaus in photos.</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">However we are discussing why we get high and low flames and</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">we would appreciate clarification. If the high flames are at</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">the antinode this is where there is maximum variation in gas</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">pressure, so sometimes there is low pressure and at other</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">times a higher pressure than normal. At the nodes the gas</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">pressure remains constant at normal pressure and we think</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">that is where we get lower flames.</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Question: Is a high flame produced at the antinode?</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Our reasoning:</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">For at least half the time there is higher pressure than</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">'normal'? Since the frquency for the best effect seems to be</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">1 kHz to 2 kHz this would imply that there is higher than</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">usual gas pressure for at least 50% of the time and this</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">pushes more gas out the holes.</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Comments please.</font></div><br><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Thanks</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Graham Foster</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">EGGS Auckland</font></div><br><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Graham Foster</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Director of Science, EGGS</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">AMI Learned Society</font></div><br><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">_______________________________________________</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); ">Phys-teach-talk mailing list</font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); "><a href="mailto:Phys-teach-talk@nzip.org.nz">Phys-teach-talk@nzip.org.nz</a></font></div><div align="left" style="text-align: left; "><font face="Geneva" size="+0" color="#000000" style="font-family: Geneva; font-size: 10pt; color: rgb(0, 0, 0); "><a href="http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz" target="_blank">http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz</a></font></div></span></blockquote></div><br></div></blockquote></div><br></body></html>