wave_mechanics Beats Question 32
Question: The wavelengths of two waves are 50 and 51 cm respectively. If the temperature of the room is 20oC, then what will be the number of beats produced per second by these waves, when the speed of sound at 0oC is 332 m/sec
[UPSEAT 1999]
Options:
A) 14
B) 10
C) 24
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
$ v _{0}=332 $ m/s.
Velocity sound at t°C is $ v _{t}=(v _{0}+0.61t) $
Therefore $ v _{20}=v _{0}+0.61\times 20=344.2 $
$ m/s $
Therefore $ \Delta n=v _{20}( \frac{1}{{\lambda _{1}}}-\frac{1}{{\lambda _{2}}} ) $
$ =344.2( \frac{100}{50}-\frac{100}{51} )=14 $
BETA
