Question

Two waves of wavelengths $50cm$ and $51cm$ produced $12$ beats per sec. The velocity of sound is

• A. 340 ms
• B. 331 ms
• C. 306 m s
• D. 360 ms

Answer 1

Answer: (C)

Number of beats produced per sec.
$=v_1-v_2=\frac{v}{{\lambda }_1}-\frac{v}{{\lambda }_2}$
$12=v\left[\frac{1}{50}-\frac{1}{51}\right]$
or, $12=\frac{v\times 1}{50\times 51}$
or, $v=12\times 50\times 51cm/s=306m/s$.