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Figure shows a tube having sound source at one end and observe at other end. Source produces frequencies upto `10000 Hz`. Speed of sound is `400 m//s`. Find the frequencies at which person hears maximum intensity. |
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Answer» The sound wave bifurcates at the juction of the straight and the rectangular parts. The wave through the straight part travels a distance `p_(1) = 10 cm ` and the wave through the rectangular part travels a distance `p_(2) = 3 xx 10 xm = 30` before they mwwt agian and travel to the receiver. The path difference between the two wave received, therefore. `Deltap = p_(2) - p_(1) = 30 cm - 10 cm = 20 cm` The wavelength of either wave is `(v)/(upsilon) rArr (400 m//s)/(upsilon)`. For constructive interference, `Deltap = nlambda`, where `n` is an integer. or, `Deltap = n.(v)/(v) rArr v = (n.v)/(Deltap)` `rArr v = (400)/(0.1) = 4000 n` Thus, the frequencies within the specified range which cause maximum of intensity are `4000 xx 1 Hz, 4000 xx 2 Hz` |
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