Wave Mechanics Question 839

Question: The minimum distance of reflector surface from the source for listening the echo of sound is

[CPMT 1997; RPMT 1999; KCET 2000]

Options:

A) 28 m

B) 18 m

C) 19 m

D) 16.5 m

Show Answer

Answer:

Correct Answer: D

Solution:

$ 2d=v\times t $ , where $ v= $ velocity of sound = 332 $ m/s $ t = Persistence of hearing = $ \frac{1}{10}\sec $ .

Therefore $ d=\frac{v\times t}{2}=\frac{332\times \frac{1}{10}}{2}=16.5 $

$ m $