ABC The two speakers shown to the right are wired the same (same fixed phase con
ID: 1340920 • Letter: A
Question
ABC The two speakers shown to the right are wired the same (same fixed phase constant) and send out sound waves at the same frequency with equal intensity. The picture to the right shows the locations of the two speakers. The distance from speaker 2 to point B is 1.75 m and the distance from speaker 1 to point B is twice as big. a) Suppose a person notices that the sound is getting louder and louder as they walk from A toward B, that it is loudest at point B, and then gets quieter as they walk toward C. Find the smallest possible frequency, f, that the sound could be that would lead to this situation. Draw an appropriate phase chart OR an appropriate wavefront picture and explain carefully why the two speakers will produce a louder sound at point B than at A or C.Explanation / Answer
At B there is constructive interference
path difference = 2*1.75 - 1.75 = 1.75 m
To get constructive interference, path difference whould be n*wavelength
To get smallest f, wavelength should be maximum. so n=1
wavelength = 1.75 m
use:
wavelength = c/f
1.75=(3*10^8)/f
f=1.71*10^8 Hz
Answer: 1.71*10^8 Hz