Wave Mechanics Question 1006
Question: At what speed should a source of sound move so that stationary observer finds the apparent frequency equal to half of the original frequency
[RPMT 1996]
Options:
A) $ \frac{v}{2} $
B) 2v
C) $ \frac{v}{4} $
D) v
Show Answer
Answer:
Correct Answer: D
Solution:
Frequency is decreasing (becomes half), it means source is going away from the observes. In this case frequency observed by the observer is $ {n}’=n( \frac{v}{v+v _{s}} ) $
Therefore $ \frac{n}{2}=n,( \frac{v}{v+v _{S}} ) $
Therefore $ v _{S}=v $
BETA
