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A source and listener move away from each other with a velocity of 10 m/s with respect to ground. If the observer finds the frequency of sound coming from the source as 1950 Hz, then the actual frequency of the source is (velocity of sound in air = 340 m/s)

  • Option 1)

    1950 Hz

  • Option 2)

    2068Hz

  • Option 3)

    2132 Hz

  • Option 4)

    2000 Hz

 

Answers (1)

best_answer

n'=n\left [ \frac{v-v_{l}}{v+v_{A}} \right ]\Rightarrow n \left [ \frac{340-10}{340+10} \right ]= n'

n= 2068Hz

 

Frequency of sound when source & observer are moving away from each other -

\nu {}'= \nu _{0}.\frac{C-V_{0}}{C+V_{s}}
 

- wherein

C= Speed of sound

V_{0}= Speed of observer

V_{s}= speed of source

\nu _{0 }= Original frequency

\nu {}'= apparent frequency

 

 


Option 1)

1950 Hz

This is incorrect

Option 2)

2068Hz

This is correct

Option 3)

2132 Hz

This is incorrect

Option 4)

2000 Hz

This is incorrect

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Plabita

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