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Sound interference

by affans
Tags: difference, phase
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Aug12-09, 07:26 PM
P: 11
1. The problem statement, all variables and given/known data

Two sound waves, from different sources with the same frequency, 540 Hz, travel in the same direction at 330m/s. The sources are in phase. What is the phase difference of the waves at a point that is 4.40 m from one source and 4.00 from the other.

2. Relevant equations

We know that [tex]\Phi[/tex] = [tex]\Delta[/tex]L / wavelength * (2pi)
We also know when the delta L / wavelentgh is a positive integer value, fully constructive interference occurs.

If delta L/ wavelength is odd integer value then fully destructive interference occurs.

and then you have your regular kinematics, and dynamics eqns.

3. The attempt at a solution

f = 540 Hz, velocity = 330m/s
f[tex]\lambda[/tex] = velocity
and we solve for lamda = 540/330 = 1.64 m

now we plug that into the phase eqn.

[tex]\Phi[/tex] = [tex]\frac{0.40}{1.64}[/tex]

that is equal to 0.2439024...

now i dont know thats my answer, or should i multiply it by 2pi . or what?
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Aug12-09, 11:20 PM
P: 211
"We know that [tex]\Phi[/tex] = [tex]\Delta[/tex]L / wavelength * (2pi)"

"[tex]\Phi[/tex] = [tex]\frac{0.40}{1.64}[/tex]"

You're missing the 2pi.

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