Points of destructive interference of sound waves?

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SUMMARY

The discussion revolves around calculating the points of destructive interference of sound waves emitted by two speakers (S1 and S2) at a frequency of 340Hz, separated by a distance of 3 meters. The correct number of points of destructive interference is established as 3, determined by the condition that the path difference (delta L) must equal n * 0.5 times the wavelength. The wavelength is calculated to be 1 meter, leading to a path difference of 2 meters when the listener is at the final position.

PREREQUISITES
  • Understanding of sound wave properties, specifically frequency and wavelength.
  • Knowledge of the principle of destructive interference in wave physics.
  • Familiarity with the equation for wavelength (w = v/f).
  • Basic geometry related to distances between sound sources and listener positions.
NEXT STEPS
  • Study the principles of wave interference, focusing on constructive and destructive interference.
  • Learn how to calculate wavelength and frequency relationships in sound waves.
  • Explore practical applications of sound wave interference in acoustics.
  • Investigate the effects of varying distances and angles on interference patterns.
USEFUL FOR

Students studying physics, particularly those focusing on wave mechanics, acoustics, and sound engineering. This discussion is also beneficial for educators teaching concepts of wave interference.

Maged Saeed
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Homework Statement


Two speakers (S1,S2), emitting sound waves of frequency 340Hz and separated by a distance of 3 m, are driven by the same oscillator. A listener starts walking from point A to S2 Along the line that joins A and S2> How many points of destructive interference will be observe? Speed of sound in are is 340 m/s

Homework Equations


w=v/f

The Attempt at a Solution


Although, it seems quite easy,I've tried to solve it many times with no reasonable result,
Wavelength will be 1 meter. And I don't know how to do after that.

the right answer is 4 but how it comes??
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What is the condition for destructive interference?
This condition has one parameter that will vary as you go towards S1. What is its initial and final value?
 
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mfb said:
What is the condition for destructive interference?
This condition has one parameter that will vary as you go towards S1. What is its initial and final value?
The condition says :
for a destructive interference, (delta L/wavelength)=n.0.5
But how can I apply it here?

The initial value of delta L equals to 1 and the final value equals 1.
 
Maged Saeed said:
The initial value of delta L equals to 1 and the final value equals 1.
I agree with the initial value, but not with the final one. What are the two distances to the speakers at the final position?
 
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mfb said:
I agree with the initial value, but not with the final one. What are the two distances to the speakers at the final position?

Sorry, I meant 3
The vertical distance between the two sources.
 
Right, that allows to find how many times you get destructive interference. But the answer is not 4.
 
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mfb said:
Right, that allows to find how many times you get destructive interference. But the answer is not 4.

I think that it is 3
Am I right??
 
Why 3?
 
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mfb said:
Why 3?
Oh , sorry
delta L will be (3-1) =2
So the numer is two.
I think I'm right now .
 
  • #10
Looks right.
 
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