PASCO WA-9612 RESONANCE TUBE - Manual (Page 9)

012-03541E Resonance Tube
5
wave pattern exists naturally at each end of the tube.
Another way to characterize the resonance states is to
say that an integral number of half wavelengths fits
between the ends of the tube.
For a closed tube (by convention, a closed tube is open
at one end and closed at the other), resonance occurs
when the wavelength of the wave (l) satisfies the
condition:
L = nl/4, n = 1, 3, 5, 7, 9,….
These wavelengths allow a standing wave pattern
such that a pressure node (displacement antinode)
occurs naturally at the open end of the tube and a
pressure antinode (displacement node) occurs naturally
at the closed end of the tube. As for the open tube, each
successive value of n describes a state in which one
more half wavelength fits between the ends of the tube.
➤ NOTE: The first four resonance states for open
and closed tubes are diagramed below. The first
resonance state (n = 1) is called the fundamental.
Successive resonance states are called overtones. The
representation in each case is relative displacement.
OPEN TUBE
N
A
N
A A
N
N
A A
N
A
N N
A A
N
A
N
A
N
A A
A A
Fundamental: Open tube
2nd Overtone: Open tube
1st Overtone: Open tube
3rd Overtone: Open tube
Resonance States:Open and Closed Tubes
N
A
N
A A
N
N
A A
N
A
N N
A A
N
A
N
A
N
Fundamental: Closed tube 1st Overtone: Closed tube
3rd Overtone: Closed tube 2nd Overtone: Closed tube
CLOSED TUBE