Influence of the termination impedance on the eigen frequency (2)
Illustration by the "boomwhackers"
The effect of the terminations on the natural frequencies of a tube is perfectly illustrated by a musical instrument for children, the boomwhacker. These instruments are plastic tubes that may be open at both ends (case 1), or closed at one end with a stopper (case 2).
In case 1, the first resonant frequency is approximately
. In case 2 the first resonant frequency is approximtely,
. An illustration of this phenomena can be seen in this video.
Interactive animation
In the case of a tube closed at its input and open at its output, the effect of the tube length and temperature can be observed by using this animation.
