Consider the resonance tube of Fig. 3-1. Assume the piston is in position B. Sou
ID: 1999816 • Letter: C
Question
Consider the resonance tube of Fig. 3-1. Assume the piston is in position B. Sound energy of a definite frequency enters the tube at A from a small speaker. A small amount of energy entering at A will go through the opening at B and to your ear. Most of the sound energy will be reflected at B back to A as in a closed pipe. For specific lengths of the closed pipe, a standing wave is produced and resonance will occur. The sound you hear will be much louder than it would be if the resonant condition did not exist. As shown in Fig. 3-2, standing waves will be produced under the condition that the positions at B, C, D, etc, are nodes of displacement. =4L L- lengtk oftube Figure 3-2: Standing Waves and Corresponding Wavelengths in a Closed Tube Note that the distances between successive points of resonance are each one-half wavelength and so wavelength is twice the distance between resonant points. Thus, if the distance between adjacent nodes is d, then d-A/2 so the wavelength -2d. So for instance, if L is the distance between the first and fifth resonant points, d would equal L/4, since four loops are included, and the wavelength would be -2 ( 4)-L/2. The source of sound for the resonance tube shown in Fig. 3-1 is a small speaker which is driven by an electronic audio oscillator in which the frequency can be closely controlled. A meter stick along the resonance tube helps in recording the positions of successive loud points.Explanation / Answer
d = lambda/2