anishaaas Posted March 14, 2016 Report Share Posted March 14, 2016 Travelling waves of wavelength 32 cm are created in a closed-open pipe X of length 40 cm and an open-open pipe Y of length 50 cm. In which pipe or pipes will a standing wave be formed? A. X only B. Y only C. neither X or Y D. both X and Y How is this calculated? Thanks for answers Reply Link to post Share on other sites More sharing options...
kw0573 Posted March 14, 2016 Report Share Posted March 14, 2016 (edited) Close ends have nodes. Open ends have antinodes (amplitude at max). As a result, closed-end has length 1/4 lambda , 3/4 lambda, 5/4 etc. Open open has 1/2, 1, 3/2, lambda. 40 is 5/4 lambda for close-open; 50 is 25/16 lambda so answer is A. X only. Edited March 15, 2016 by kw0573 2 Reply Link to post Share on other sites More sharing options...
anishaaas Posted March 15, 2016 Author Report Share Posted March 15, 2016 Thank you! So what I understand by this is (even though it is a paper 1 question): For the closed-open: L = x/4 * lambda 40 = x/4 * 32 x=5 -> since this is a whole number (and odd), a standing wave will be created. For open-open: L = x/2 * lambda 50 = x/2 * 32 x = 3.125 -> since this is a decimal, a standing wave will not be created. Therefore answer is A. X only. Is my thoughtprocess correct? 1 Reply Link to post Share on other sites More sharing options...
kw0573 Posted March 15, 2016 Report Share Posted March 15, 2016 Yeah that seems a more systematic way of solving! 1 Reply Link to post Share on other sites More sharing options...
anishaaas Posted March 18, 2016 Author Report Share Posted March 18, 2016 Thank you! Reply Link to post Share on other sites More sharing options...
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