# Physics: wavelength of sound waves

## 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).

#### Attachments

• 9F37DE66-B2C2-4909-A504-64604852B199.jpeg
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mfb
Mentor
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.

mfb
Mentor
No. That looks like something for constructive interference.

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?

mfb
Mentor
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.

mfb
Mentor
You do not have a standing wave here. You have two waves from different tubes interfering.

• YMMMA
You do not have a standing wave here. You have two waves from different tubes interfering.
Yes, okay then. Thanks!