Q. A resonance pipe is open at both ends and 30 cm of its length is in resonance with an external frequency 1.1 kHz. If the speed of sound is 330 m/s, which harmonic is in resonance?
A) First
B) Second
C) Third
D) Fourth
Explanation
(b) Fundamental frequency of open pipe
$first\ harmonic = n_{1} = \frac{v}{2\iota} = \frac{330}{2 \times 0.3} = 550Hz$
$second\ harmonic = 2 \times n_{1} = 1100Hz = 1.1\ kHz$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.