Two in-phase loudspeakers are 3.0 m apart. They emit sound with a frequency of 490 Hz. A microphone is placed half-way between the speakers and then moved along the line joining the
Two speakers until the first point of constructive interference is found. At what distance from that
Midpoint is that first point? The speed of sound in air is 343 m/s.
A) 0.50 m
B) 0.35 m
C) 0.70 m
D) 0.18 m
E) There is no point in that line where constructive interference occurs.

Question

Quizplus · Accepted Answer

The wavelength of the sound is calculated using the formula λ = v/f, where v is the speed of sound and f is the frequency. For 490 Hz, λ = 343 m/s / 490 Hz ≈ 0.7 m. Constructive interference occurs at integer multiples of the wavelength. The first point of constructive interference from the midpoint is at λ/2, which is 0.35 m.

Two In-Phase Loudspeakers Are 3