Two identical loudspeakers are 2 m apart. A person stands 4.6 m from one speaker and 3.4 m from the other. What is the lowest frequency at which destructive interference will occur at this point?

Answer 1

Destructibe interference will occur if the difference between the distances to the two speakers is n + 1/2, where n is an integer zero or higher. When n = 0, you get the longest wavelength and lowest frequency with destructive interference.

Therefore 4.6 - 3.4 = 1.2 = (wavelength)/2
wavelngth = 2.4 m
freq

Answer 2

Destructive interference will occur if the difference between the distances to the two speakers is n + 1/2, where n is an integer equal to zero, or higher. When n = 0, you get the longest wavelength and lowest frequency with destructive interference.

Therefore 4.6 - 3.4 = 1.2 = (wavelength)/2
wavelength = 2.4 m
frequency = (speed of sound)/2.4 m
= 140 Hz (approx.)