(adsbygoogle = window.adsbygoogle || []).push({}); [SOLVED] Amplitude of Sound Waves from Two Sources at a Point

Problem.Two sources, A and B, emit sound waves, in phase, each of wavelength [itex]\lambda[/itex] and amplitude [itex]D_M[/itex]. Consider a point P that is a distance [itex]r_A[/itex] from A and [itex]r_B[/itex] from B. Show that if [itex]r_A[/itex] and [itex]r_B[/itex] are nearly equal ([itex]r_A - r_B \ll r_A[/itex]). then the amplitude varies approximately with position as

[tex]\frac{2D_M}{r_A} \, \cos \frac{\pi}{\lambda} (r_A - r_B)[/tex]

Let D(x, t) be the function that describes the displacement of the sound waves at some time t and a distance x from the source. I figure that the displacement at point P must be [itex]D(r_A, t) + D(r_B, t)[/itex] right? One thing I'm noticing is that the expression for the amplitude given in the problem statement does not vary with time. What gives?

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# Homework Help: Amplitude of Sound Waves from Two Sources at a Point

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