Wave Mechanics Beats Question 27
Question: Two waves of lengths 50 cm and 51 cm produced 12 beats per second. The velocity of sound is
[CBSE PMT 1999; Pb. PET 2001; AFMC 2003]
Options:
A) 306 m/s
B) 331 m/s
C) 340 m/s
D) 360 m/s
Show Answer
Answer:
Correct Answer: A
Solution:
$ n _{1}=\frac{v}{{\lambda _{1}}}=\frac{v}{0.50} $ and $ n _{2}=\frac{v}{{\lambda _{2}}}=\frac{v}{0.51} $
$ \Delta n=n _{1}-n _{2}=v[ \frac{1}{0.05}-\frac{1}{0.51} ]=12 $
Therefore $ v=\frac{12\times 0.51\times 0.50}{0.01}=306 $
$ m/s $
BETA
