Two loudspeakers are placed side by side and driven by the same source at 525 Hz.A listener is positioned in front of the two speakers and on the line separating them,thus creating a constructive interference at the listener's ear.If one of the speakers is gradually pushed toward the listener,how far must it be moved to repeat the condition of constructive interference at the listener's ear? (The speed of sound = 340 m/s. )
A)1.5 m
B)0.65 m
C)0.32 m
D)0.16 m
E)3.1 m

Question

Quizplus · Accepted Answer

The distance between the speakers must be equal to half a wavelength to create constructive interference. The wavelength of a sound wave is given by the formula:$$\lambda = v/f$$where:* $$\lambda$$ is the wavelength in meters* $$v$$ is the speed of sound in meters per second* $$f$$ is the frequency in HertzIn this case, the frequency is 525 Hz and the speed of sound is 340 m/s, so the wavelength is:$$\lambda = 340 m/s / 525 Hz = 0.65 m$$Therefore, the speakers must be moved 0.65 m closer to the listener to create constructive interference again.

Two Loudspeakers Are Placed Side by Side and Driven by the Same