Two in-phase loudspeakers are some distance apart.They emit sound with a frequency of 536 Hz.A microphone is moved between the speakers along the line joining the two speakers with a constant speed of 1.60 m/s.What beat frequency is observed? The speed of sound in air is 343 m/s.
A)5.00 Hz
B)6.00 Hz
C)7.00 Hz
D)8.00 Hz
E)9.00 Hz

Question

Quizplus · Accepted Answer

The beat frequency is determined by the Doppler effect as the microphone moves. The frequency shift is given by f' = f(v + v_m)/v, where v is the speed of sound, v_m is the speed of the microphone, and f is the original frequency. The beat frequency is twice the frequency shift, which calculates to approximately 5 Hz.

Two In-Phase Loudspeakers Are Some Distance Apart