# Sound interference

by affans
Tags: difference, phase
 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 $$\Phi$$ = $$\Delta$$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$$\lambda$$ = velocity and we solve for lamda = 540/330 = 1.64 m now we plug that into the phase eqn. $$\Phi$$ = $$\frac{0.40}{1.64}$$ that is equal to 0.2439024... now i dont know thats my answer, or should i multiply it by 2pi . or what?
 P: 211 "We know that $$\Phi$$ = $$\Delta$$L / wavelength * (2pi)" "$$\Phi$$ = $$\frac{0.40}{1.64}$$" You're missing the 2pi.