Sound/Signal Propagation through glass?

  • Context: Undergrad 
  • Thread starter Thread starter Kurama35
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    Glass Propagation
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Discussion Overview

The discussion revolves around the challenges of using an ultrasonic transducer to vibrate water through a glass barrier. Participants explore the effectiveness of sound and signal propagation through glass and its interaction with water, focusing on the experimental setup and the expected outcomes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant describes using a 40kHz ultrasonic transducer placed against a thin sheet of glass with water on top, expressing concern that the water is not moving as expected.
  • Another participant suggests that if the glass is vibrating, the water should also vibrate, questioning the participant's expectations of movement.
  • There is a discussion about the potential high attenuation of ultrasonic frequencies in water, which may affect the visibility of movement.
  • Some participants propose that the transducer may not be effectively coupled with the glass, leading to inefficiencies in energy transfer.
  • One participant raises the question of whether the setup is designed for air or dense materials, suggesting that a mismatch could hinder performance.
  • There are suggestions to explore resonance and the effects of different frequencies on the movement of water versus other materials like crumbs.
  • Concerns are raised about the scientific approach taken by the original poster, with some participants advocating for a more structured method of experimentation.
  • Another participant notes that the observed movement of the glass does not correlate with movement in the water, prompting further inquiry into the nature of the vibrations.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of the experimental setup and the expected outcomes. There is no consensus on the reasons for the lack of movement in the water or the appropriateness of the experimental approach.

Contextual Notes

Participants note limitations in the information provided about the experimental setup, including the specific conditions under which the transducer operates and the characteristics of the materials involved. There is also uncertainty regarding the interaction between the ultrasonic waves and the water droplets.

Who May Find This Useful

This discussion may be of interest to individuals exploring ultrasonic applications, sound propagation through different media, and experimental physics related to wave behavior and material interactions.

  • #31
Kurama35 said:
It does not necessarily need to be ultrasound but I was under the impression that it would work better.

What do you mean by matching my power into the glass?

When a wave passes across a boundary between two media with different wave speeds (acoustic impedance), energy is reflected. The bigger the ratio of the two speeds, the more energy is reflected - hence the jelly that is excludes the air between ultrasound head and tummy - to exclude air. The scan works because of the small amount of power, reflected at the boundary between different tissue densities (speeds).

Any ultrasound transducer will be designed for a particular medium, to avoid the problem of getting power in, in the first place. Water /glass etc have very different speeds from air so reflections are particularly problematic when air is involved. This is why I asked about the original purpose for your transducer. Also, what is the sort of power it produces? A transducer used in an ultrasonic cleaning bath would be matched to the water (natch) but a School Demo ultrasound transducer would be suited to air. Matching the 'wrong one' involves a 1/4 wavelength layer of an intermediate density material not trivial.

If there is a particular job you want this to do then a few more details could be useful.
 
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  • #32
Hi, is this a set-up for ultrasound NDT testing? May I know your set up and where do you get the glass sample?
 
  • #33
fiza said:
Hi, is this a set-up for ultrasound NDT testing? May I know your set up and where do you get the glass sample?

Hi fiza,
Welcome to PF :smile:
THis thread is over a year old, the original posted hasn't returned since then, he may no longer be aroundDave
 

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