A music tuner uses a 550 Hz tuning fork to tune the frequency of a musical instrument. If the tuner hears a beat frequency of 2 Hz, what is the frequency of the instrument?

a) It must be 552 Hz

b) It must be 548 Hz

c) It could be either 552 Hz or 548 Hz

d) It is neither 552 Hz or 548 Hz

c) It could be either 552 Hz or 548 Hz

Explanation:

In the phenomenon of beat we hear a series of high and low intensity sound in quick succession which dies down after some time. Number of high intensity sound that we hear per second is called beat frequency. Beat is generated when sound from two sources mix up or interfere with each other. It generates in the air region or pocket having low and high intensity sound. When this sound passes our ear we hear beats.

Beat frequency that is heard is equal to difference of frequency of sound that are interfering.

In the present case, tuning fork with frequency 550 and a music instruments are sounded together. Beat frequency heard is 2 Hz. So their frequency difference will be 2. Hence the musical instrument may have frequency of 550+2 or 550 - 2. or 552 or 448 Hz. Hence option c)

is correct