Solving Striae in Kundt Tube Vibrations

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In summary, the striae in the vibrations of the kundt tube are not well defined and there is no clear cause.
  • #1
DaTario
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Hi All,

I have searched in some places but ´had no success in finding an explanation to the appearance of striae in the vibrations of the kundt tube. The powder vibrates as a response to an incoming sound wave front, and show a larger patern which is nicely explained by the theory of open tubes (or partially opened tubes). But in a smaller scale, the appearance of striae (typically with wave length of centimeters) has no well defined cause.

I appreciate the contributions on this subject,

Best wishes

DaTario
 
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  • #2
Aditional comments:

some think these striae have to do with higher harmonics in the tube, but regarding the distance between adjacent striae these harmonics would have to have frequencies of around 33000 Hz, which seems unlikely.

best wishes

DaTario
 
  • #3
The pure fundamental frequency is calculated negectling end effects.
End effects cause the wave in the tube to be not exactly sinusoidal.
Fourier analysis of the actual shape can show very high harmonics.
Which higher harmonic is dominant would depend on the R/L of the tube.
 
  • #4
How exactly is the sound generated?

As I remember (very long time ago), the tube was made to shriek by dragging a rosin cloth along it. In this case, the frictional excitation would have a very complex waveform that would make all sorts of local nodes, and the spacings involved would not be linked sound waves in the tube, but by which parts of the glass were mechanically stationary by bulk properties of the glass and the shape section. The larger scale repetition of these groups of striations would be related to the sound fundamental wavelength.

Analogous to this is when a centrally fixed steel square plate is bowed to resonate. The powder patterns revealing resonance modes show the parts of the plate that are mechanically stationary, not where sound waves in air might have a standing wave envelope.

OK - this is just my lame notion.. speculation if you like, but I have seen those happen in dust on top of corrugated steel sheeting where a piece is being dragged off a pile. The shriek is unpleasant, but the wavelength heard is no way associated with the spacings. Just because they happen when the sound is heard, does not mean one cause the other. Rather, both effects had a common excitation.
 
  • #5
thank you both.

I am wondering if it could have something to do with the velocity of sound in the glass. Could it be?

best wishes

DaTario
 

1. What is a Kundt tube and how is it used in scientific research?

A Kundt tube is a cylindrical tube used to study acoustic vibrations and the properties of different materials. It consists of a hollow tube with a movable piston at one end and a sound source at the other. By varying the frequency of the sound and measuring the resulting vibrations, scientists can determine the speed of sound in different materials and investigate their acoustic properties.

2. What is "striae" and how does it affect the vibrations in a Kundt tube?

Solving striae in Kundt tube vibrations refers to the phenomenon of small vertical lines or ridges that form on the surface of the material being studied. These striae can change the behavior of the vibrations, leading to inaccurate results. Therefore, it is important to address and minimize the effects of striae in order to obtain accurate and reliable data from Kundt tube experiments.

3. What are the main causes of striae in Kundt tube vibrations?

The main causes of striae in Kundt tube vibrations include imperfections in the material being studied, uneven application of the powder used to visualize the vibrations, and irregularities in the tube itself. Other factors, such as air currents and vibrations from external sources, can also contribute to the formation of striae.

4. How can scientists solve striae in Kundt tube vibrations?

There are several techniques that can be used to solve striae in Kundt tube vibrations. One method is to carefully prepare the material being studied to ensure a smooth and uniform surface. Another approach is to use different types of powders or visualization techniques to minimize the effects of striae. Additionally, modifying the set-up of the Kundt tube experiment, such as adjusting the frequency of the sound source, can also help reduce the presence of striae.

5. Why is it important to solve striae in Kundt tube vibrations?

Addressing and solving striae in Kundt tube vibrations is crucial for obtaining accurate and reliable data in scientific research. Striae can significantly alter the behavior of the vibrations and lead to incorrect conclusions about the properties of the material being studied. By minimizing the effects of striae, scientists can ensure the validity of their experimental results and contribute to the advancement of knowledge in their field of study.

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