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Echo and, reverberation., Sherp, Distant walus, Sharp, creaked in front of, Sounds, after Some time, or Cliffs get seflected ond, hear, seflected foom these, heard ofter, distant rigid, buildings, we, back, Our, Own, Sound, obstacles, The, Saund, they are seflected, bounderies, aut, Such as, wells, cliffs, is Called echo,, or, Echo is heard if the rigid boundary, reflecting Sound, than, is, distance more, ot, a, 17 m, Oway from us., In Small room the distance of, rigid boundery Such as, and, wals, roof, wway,, floor, hence, Case, to the, has, ther cwords,, for Some move, Source has, This, are lers than, echo, is heard But in this, the reflected Sound keep Coming, no, after the, Souce, Car, even, Stopped, Producing, Sound In., Sownd, we keep hearing Sound, even, afterthe,, time, Stolped Pooducing Sound, fer Sistance, of Sound, aftertue, Source hps Stofed, is Called, Producing Sound, reverberation.
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10, Stationary waves, in, air columns, A Column of, Can be Set into, air enclosed, Vrbrations, it's mouth, in a Pipe, by blowing, air, across, by holding, e Vibrating tuning fock, Then longitednl, the, other, backwards. Because of, the, longitudinal, a, near it's month, wavey n travel thougls, Pipe & get oeflected, at the, cnd! fre seftected, Weeve move, Suferfostion of, advancing wave, wave & reflected, Stationary, are Set up, Closed end,, wover, air, Column, At the, the air, & there fore, ofen end the, for, antinode, farticles, a node, free to vibrate, is formed. At the, Porticles have maximurs, ore, not, air, and, freedong for movement, is formed there, hence an, Tf a, end and ofen at the, a Pipe is Closd at one, ether end, it is, On the other hand, it the Pile is ofen at both the ends, Called a, Closed Pipe, on, open Pile., An ar Column in a closcd Pipe, Con vibrate iD, or on ofen Pipe, number, ways gring notes of, mode f vibration, of, di fferent Pitch. The, with the lowest, fundamental mode, is called tie fundamental, The Vibrations, Called, requeneyis Called, and, the frequeay, freyueny., with higher frequeney, overtones., are
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If the frequencies of tue, intigral multille of, frequeny,they, overtones, the fundamertal, Called harmonics,, Ore, Modes of Vibration of, Closed Cesed Pipe:, Our Column in a, AN, AN, AN, AN, AN, AN, (a), (6), (), be the length of a, Closed Pipe & v be the Velocity of sound, Closed, Let, Column, in, Pife, air. The, Vibrates, air, such a, way that, in, antinode, and, end what ever, is formed, at the, mode, always, aut, the, noder, Closed, of, open end, be, the, Vibration.
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12, In the first, the fundamental mode, node (N) is formed at, antinode (AnN), or, of, uibration,, the Closed end, formed, Therefore, Pire, Let v, be ithe frequency, and, an, OPen end, length & L, is, Shown in figla), of the, at the, the entire, Comprises of havf a Segment, the wavelength, and d, be, of' the fundamental, note Then, L=$ Segment, =, 4, di=4L, or, (1), 2i is the foequency, fundemental, facquescy., In the Second mode of vibration as Shown, n fig (6), the, Comprises of :5 Segments., the frequenty & de be the wavelangts, 4 the Rirst' overtone., length L of the fipe, Let , be, L=1.5 Segment, 3 dz, 3, dz =4L, OY, 3 V, (2), 4L, dz, 4/3, This frequescyis the third hamonics
