Sound/Signal Propagation through glass?

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  • #26
olivermsun
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So would you mind explaining what the end goal is?
 
  • #27
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One favorite way (depends if you have big enough droplets) is to shine a bright and well-directed light through a droplet and see if you can see fringing/shadowing due to the droplet. See if the shadow moves when you turn on the 'music.'

I'm really surprised that you don't notice any movement AT ALL in the droplet if the entire glass plate is visibly moving. Isn't it at least moving WITH the plate?

I think that's hard to explain. It's probably moving with the plate, but if you look at the water compared to the glass, its location doesn't seem to be changing.
 
  • #28
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So would you mind explaining what the end goal is?

Basically, I want to move water on the other side of the glass using sound. I'd rather not give out any more details about the why.
 
  • #29
sophiecentaur
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Basically, I want to move water on the other side of the glass using sound. I'd rather not give out any more details about the why.

In that case, you need to consider matching your power into the glass for a start - or you will not get the power transfer that you need. Also, does it have to be ultrasound and not audible sound?
 
  • #30
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In that case, you need to consider matching your power into the glass for a start - or you will not get the power transfer that you need. Also, does it have to be ultrasound and not audible sound?

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?
 
  • #31
sophiecentaur
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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.
 
  • #32
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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
davenn
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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 around


Dave
 

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