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Rijke's tube turns heat into sound, by creating a self-amplifying standing wave. It is an entertaining phenomenon in acoustics and is an excellent example of resonance. ==Discovery== P. L. Rijke was a professor of physics at the Leiden University in the Netherlands when, in 1859, he discovered a way of using heat to sustain a sound in a cylindrical tube open at both ends.〔Pieter L. Rijke (1859) (“On the vibration of the air in a tube open at both ends,” ) ''Philosophical Magazine'', vol. 17, pages 419-422; also published as: (“Notiz über eine neue Art, die in einer an beiden Enden offenen Röhre enthaltene Luft in Schwingungen zu versetzen” (Notice of a new way to set into oscillation the air contained in a tube with both ends open) ), ''Annalen der Physik und Chemie'', series 2, vol. 107, pages 339-343 (1859) (citation: ''Annalen der Physik'', vol. 183, pages 339--343 ).〕 He used a glass tube, about 0.8 m long and 3.5 cm in diameter. Inside it, about 20 cm from one end, he placed a disc of wire gauze as shown in the figure on right. Friction with the walls of the tube is sufficient to keep the gauze in position. With the tube vertical and the gauze in the lower half, he heated the gauze with a flame until it was glowing red hot. Upon removing the flame, he obtained a loud sound from the tube which lasted until the gauze cooled down (about 10s). It is safer in modern reproductions of this experiment to use a borosilicate glass tube or, better still, one made of metal. Instead of heating the gauze with a flame, Rijke also tried electrical heating. Making the gauze with electrical resistance wire causes it to glow red when a sufficiently large current is passed. With the heat being continuously supplied, the sound is also continuous and rather loud. Rijke seems to have received complaints from his university colleagues because he reports that the sound could be easily heard three rooms away from his laboratory. The electrical power required to achieve this is about 1 kW. Lord Rayleigh, who wrote the definitive textbook on sound in 1877, recommends this as a very effective lecture demonstration. He used a cast iron pipe 1.5 m long and 12 cm diameter with two layers of gauze made from iron wire inserted about quarter of the way up the tube. The extra gauze is to retain more heat, which makes the sound longer lasting. He reports in his book that the sound rises to such intensity as to shake the room!〔John Wm. Strutt (Lord Rayleigh) (1879) “Acoustical observations,” ''Philosophical Magazine'', 5th series, vol. 7, pages 149-162.〕 A "reverse" Rijke effect — namely, that a Rijke tube will also produce audio oscillations if ''hot'' air flows through a ''cold'' screen — was first observed by Rijke's assistant Johannes Bosscha〔Bosscha's discovery is mentioned on pages 342-343 of: Rijke (1859) "Notiz über eine neue Art,...," ''Annalen der Physik'', vol. 183, pages 339-343.〕 and subsequently investigated by German physicist Peter Theophil Rieß.〔P. Riess (1859) ("Das Anblasen offener Röhren durch eine Flamme" (The sounding of open tubes by a flame) ), ''Annalen der Physik und Chemie'', series 2, vol. 108, pages 653-656 (citation: ''Annalen der Physik'', vol. 184, pages 653-656 ).〕〔P. Riess (1860) ("Anhaltendes Tönen einer Röhre durch eine Flamme" (Sustained tones of a tube by a flame) ), ''Annalen der Physik und Chemie'', series 2, vol. 109, pages 145-147 (citation: ''Annalen der Physik'', vol. 185, pages 145-147 ).〕〔Lord Rayleigh mentions the discoveries of Bosscha and of Riess in: John Wm. Strutt (Baron Rayleigh), ''The Theory of Sound'', 2nd ed. (Macmillan, 1896 ), vol. 2, pages 233-234.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Rijke tube」の詳細全文を読む スポンサード リンク
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