Sound wave Interference from Two Speakers

AI Thread Summary
To determine quiet spots based on sound wave interference from two speakers, the "n" value indicates the type of interference occurring. Whole numbers for "n" signify constructive interference, resulting in a noisy spot, while non-whole numbers indicate destructive interference, leading to a quiet spot. In the given scenario, the calculated path difference of 3.0 m corresponds to an "n" value of 2.5, indicating destructive interference. Therefore, the student will not be standing in a quiet spot, as the interference is constructive. Understanding the relationship between path difference and wavelength is crucial for identifying these spots.
aatari
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Hi guys I am having trouble determining a quite spot based on where you stand in respect to distance from the speakers. I have solved the question below but I need someone to explain to me how the "n" value can be used to determine a quite or not-quite spot. Am I looking for whole numbers? If n is a whole number its constructive interference and therefore, noisy spot and if n is not a whole number then its destructive interference and a quite spot?

Can someone please help!

Homework Statement


A student enters Best Buy prepared to buy a pair of speakers. Before he does, he conducts an experiment with them. He places them 4.0 m apart and then connects a signal generator to both speakers that produces a single tone of 240 Hz. He then walks in front of the speakers so that he is 2.0 m from one speaker and 5.0 m from the other. If the speed of the sound in the room is 360 m/s, will he be standing in a “quiet” spot? Explain.

Homework Equations


v = f. λ
PD = (n-1/2) λ

3. The Attempt at a Solution

λ = 360/240
λ = 1.5 m

PD = (n-1/2) λ
|5.0 – 2.0| = (n – 0.5) 1.5
3.0 = 1.5n – 0.75
3.0 + 0.75 = 1.5n
3.75 = 1.5n
n = 3.75/1.5
n = 2.5
 
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I would recommend that you approach this more conceptually. You have found the wavelength. How does the path difference compare to λ?
 
TSny said:
I would recommend that you approach this more conceptually. You have found the wavelength. How does the path difference compare to λ?
It double the size of the wavelength. So its constructive interference and the person will not be standing at a quite spot.
 
Yes, I think that's all there is to it. (quite → quiet)
 
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