Chap_28_Disc[1] - 28-8. A microphone is located on the line...

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28-8 . A microphone is located on the line connecting two speakers that are 0.845 m apart and oscillating 180° out of phase. The microphone is 2.25 m from the midpoint of the two speakers. What are the lowest two frequencies that produce an interference maximum at the microphone’s location?
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The equation that is true for all waves is f v Where in this case, v is the speed of sound. So, v f The equation that gives us what the problem is looking for is now telling us to find . So, what   kind of physics is involved here? Interference! For an interference maximum, as the problem specifies, we set the path length difference equal to a whole number of wavelengths. m Now to our primary mi   21 2 1 2 1 ssion, which is to find . Let's let the leftmost speaker's distance to the microphone be , and the distancefrom the speaker to its right be . So, 0.845m 2.00m 2.4225m. 2 0.8        45m 1.5775m. But wait! The problem also 2 specifies that the two speakers are oscillating 180 out of phase, which is or out of phase. Should we fuss and worry about whether to 2 add or subtra 12 ct this to or ? Well, as Wednesday said in "The Addams Family","Does it matter?" So, 2.4225m 1.5775m . 22 Well, how about that? The path length difference (not counting the   "out of phase"part) is the separation distance between the two speakers! m 2 1 m So, let's solve this for . 2 = Since the problem is asking for the first TWO f 1 m 2   requencies, we need to find the first TWO s. These would correspond to m 0, and m 1.
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This note was uploaded on 10/13/2011 for the course PHY 102 taught by Professor Alexandrakis during the Fall '06 term at FIU.

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Chap_28_Disc[1] - 28-8. A microphone is located on the line...

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