Physics: wavelength of sound waves

  • Thread starter YMMMA
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  • #1
156
10

Homework Statement


Stated in the attached file.

Homework Equations


Wavelength = 2 times length divided by harmonic
I don’t know if it’s the relevant equation

The Attempt at a Solution


I used the equation I wrote. So, if the left side is 10cm longer, I guess it might be 2(10).
 

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Answers and Replies

  • #2
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20 cm is right, but I'm not sure you used the right formula.
10 cm corresponds to one of 1/2, 3/2, 5/2, ... times the wavelength, only the first option leads to a possible answer.
 
  • #3
156
10
I used this formula, is it the right one?
 

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  • #4
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No. That looks like something for constructive interference.
 
  • #5
156
10
20 cm is right, but I'm not sure you used the right formula.
10 cm corresponds to one of 1/2, 3/2, 5/2, ... times the wavelength, only the first option leads to a possible answer.
I think that’s the same rule. If wavelength=2*length / n, where n can be 1,2,3,4,5,6,...(the one wrote in the picture)
It’s basically the same as you said but solving for length not wavelength. I mean, length =1/2 *n*wavelength.
Right?
 
  • #6
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For destructive interference you want the length difference to be (n+1/2) wavelengths where n is an integer: L = (n+1/2)λ or 2L = (2n+1)λ or ##\lambda = \frac{2L}{2n+1}##. Your formula works if you require n in it to be odd.
 
  • #7
156
10
I am confused now. That’s a little bit different from I have learned. Or is this rule for these type of questions?
 

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  • #8
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You do not have a standing wave here. You have two waves from different tubes interfering.
 
  • #9
156
10
You do not have a standing wave here. You have two waves from different tubes interfering.
Yes, okay then. Thanks!
 

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