Interference: Two stereo speakers mounted 4.52 m apart on a wall emit identical in-phase sound waves. You are standing at the opposite wall of the room at a point directly between the two speakers. You walk 2.11 m parallel to the wall, to a location where you first notice that the sound intensity drops to zero. If the wall along which you are walking is 10.7 m from the wall with the speakers, what is the wavelength of the sound waves? CAREFUL! The distance to the wall is NOT much greater than the distance between the speakers.
A) 1.7 m
B) 2.1 m
C) 2.6 m
D) 2.9 m

Question

Quizplus · Accepted Answer

The path difference between the sound waves from the two speakers at the point of first destructive interference is half a wavelength. Using geometry and the given distances, the wavelength can be calculated to be approximately 1.7 m.

Interference: Two Stereo Speakers Mounted 4