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THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

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Problems for Chapter 8 1719. A 400-Hz plane wave of 0.2 W power propagates down an infinitely longpipe of 5 cm diameter. Find the power reflected, the power transmitted alongthe pipe, and the power transmitted out through a simple orifice of 1.2 cmdiameter.10. A 5-cm pipe carries water. It is planned to filter out plane waves traveling inthe water by using sections of pipes 10 cm in diameter to serve as expansionchambertype of filters.(a) Find the minimum length of the filter section that will most effectivelyfilter out a sound of 1 kHz.(b) If it is desired to have a filtering action lessen the level of intensity by35 dB, how many sections must be used? Disregard the effects of anyinteraction between the individual filter sections.11. Find the transmission coefficient of a low-pass filter that consists of a circularpipe of 3.0 cm radius mated with a circular expansion chamber that is 12.0 cmlong. Assume that wavelength λ is 30 cm (recall that k = 2π/λ).

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