Q. Two waves of wavelengths $50\ cm$ and $51\ cm$ produced 12 beats per second. The velocity of sound is
A) $306\ m/s$
B) $331\ m/s$
C) $340\ m/s$
D) $360\ m/s$
Explanation
(a) $n_{1} = \frac{v}{\lambda_{1}} = \frac{v}{0.50}$ and $n_{2} = \frac{v}{\lambda_{2}} = \frac{v}{0.51}$
$\Delta n = n_{1} - n_{2} = v\left\lbrack \frac{1}{0.50} - \frac{1}{0.51} \right\rbrack = 12$
$\Rightarrow v = \frac{12 \times 0.51 \times 0.50}{0.01} = 306\ m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.