In the figure below, S is a small loudspeaker driven by an audio oscillator with
ID: 1522137 • Letter: I
Question
In the figure below, S is a small loudspeaker driven by an audio oscillator with a frequency that is varied from 1000 Hz to 2000 Hz, and D is a cylindrical pipe with two open ends and a length of 28.0 cm.
(a) At how many frequencies does the sound from the loudspeaker set up resonance in the pipe?
_______ frequencies
(b) What is the lowest frequency (of the given range) at which resonance occurs?
________ Hz
(c) What is the second lowest frequency (of the given range) at which resonance occurs?
________ Hz
Explanation / Answer
L = 28 cm , v =344 m/s
(a) fundamental frequency for open pipe f1 = v/2L
f1 = 344/(2*0.28)
f1 = 614.3 Hz
f2 = 2*f1 = 2*614.3 = 1228.6 Hz
f3 = 3*f1 = 3*614.3 = 1842.9 Hz
only two resonant frequencies are possible
(b) f2 = 1228.6 Hz
(C) 1842.9 Hz