Answer:
The beat frequency is 0.0019 MHz.
Explanation:
Given that,
Velocity = 0.32 m/s
Frequency = 4.40 MHz
Speed of wave = 1540 m/s
We need to calculate the frequency
Case (I),
Observer is moving away from the source
Using Doppler's effect
[tex]f'=\dfrac{v-v'}{v}f[/tex]
Where, v' = speed of observer
Put the value into the formula
[tex]f'=\dfrac{1540-0.32}{1540}\times4.40[/tex]
[tex]f'=4.399\ MHz[/tex]
Case (II),
Cell is as the source of sound of frequency f' and it moving away from the observer.
Using formula of frequency
[tex]f''=\dfrac{v-v_{s}}{v+v_{s}}\times f[/tex]
[tex]f''=\dfrac{1540-0.32}{1540+0.32}\times4.399[/tex]
[tex]f''=4.3971\ MHz[/tex]
We need to calculate the beat frequency
[tex]\Delta f= f'-f''[/tex]
[tex]\Delta f=4.399-4.3971=0.0019\ MHz[/tex]
Hence, The beat frequency is 0.0019 MHz.
