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The fundamental frequency of an air column in a pipe closed at one end is in unison with the third overtone of an open pipe. Calculate the ratio of lengths of their air columns. |
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Answer» Given: Fundamental frequency for closed pipe = Third overtone of open pipe. To find: Ratio of lengths of air columns in both the pipes \((\frac{l_c}{l_o})\) Formulae: a. Fundamental frequency of pipe closed at one end: nc = \(\frac{v}{4l_c}\) b. Fundamental frequency of pipe open at both ends: no = \(\frac{v}{2l_o}\) c. Third overtone of open pipe: n3 = 4n0 Calculation: Fundamental frequency of closed pipe (nc) is same as third overtone of open pipe. ∴ nc = n3 ∴ nc = 4n0 ∴ \(\frac{v}{4l_c}\) = 4[\(\frac{v}{2l_o}\)] ∴ \(\frac{v}{4l_c}\) = \(\frac{2}{l_o}\) ∴ \(\frac{l_c}{l_o}\)= \(\frac18\) The ratio of lengths of air columns in closed pipe and open pipe is 1:8. |
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