A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15 ms-1. Then, the frequency of sound that the observer hears in the echo reflected from the cliff is :
(Take velocity of sound in air = 330 ms-1)
765 Hz
800 Hz
838 Hz
885 Hz
As discussed in
Frequency of sound when observer is stationary and source is moving towards observer -
- wherein
speed of sound
speed of source
original frequency
apparent frequency
Apparent frequency,
Option 1)
765 Hz
This option is incorrect.
Option 2)
800 Hz
This option is incorrect.
Option 3)
838 Hz
This option is correct.
Option 4)
885 Hz
This option is incorrect.