Q. The wavelengths of two waves are 50 and $51\ cm$ respectively. If the temperature of the room is $20℃$, then what will be the number of beats produced per second by these waves, when the speed of sound at $0℃$ is $332\ m/sec$
A) 14
B) 10
C) 24
D) None of these
Explanation
(a) $v_{0} = 332\ m/s.$ Velocity sound at $t℃$ is $v_{t} = (v_{0} + 0.61\ t)$
$\Rightarrow v_{20} = v_{0} + 0.61 \times 20 = 344.2\ m/s$
$\Rightarrow \mathrm{\Delta}n = v_{20}\left( \frac{1}{\lambda_{1}} - \frac{1}{\lambda_{2}} \right) = 344.2\left( \frac{100}{50} - \frac{100}{51} \right) = 14$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.