Q. If the velocity of sound in air is $336\ m/s.$ The $maximum$ length of a closed pipe that would produce a just audible sound will be
A) $3.2\ cm$
B) $4.2\ m$
C) $4.2\ cm$
D) $3.2\ m$
Explanation
(b) Minimum audible frequency $= 20\ Hz$
$\Rightarrow \frac{v}{4l} = 20 \Rightarrow l = \frac{336}{4 \times 20} = 4.2\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.