Two Loudspeakers, a and B, Are Separated by a Distance

Multiple Choice

Two loudspeakers, A and B, are separated by a distance of 2.0 m. The speakers emit sound waves at a frequency of 680 Hz that are exactly out of phase. The speed of sound is 343 m/s. How far from speaker A along the +x axis will a point of constructive interference occur?

A) 0.25 m
B) 0.30 m
C) 0.46 m
D) 0.88 m
E) 0.98 m