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In Reply to: RE: Houston, we have a problem posted by geoffkait on August 26, 2007 at 12:31:39
Mechanical movement dissipates the energy as heat. It's the simple laws of thermodynamics. The piezo effect also works in the inverse, as evidenced in quartz oscillators.
Stu
Follow Ups:
Stu,
You have definitely piqued my interest. Of what form is the quartz that you are using for this application? Does the size matter? Where do you get it?
Inquiring minds...
Regards, Rick
You previously said "EMI/RFI fields are converted to heat." Now you say "mechanical energy is converted to heat." Which is it, or is it both?In any case, while a number of atomic mechanisms in mineral crystals have been identified, by NASA and many other organizations and individuals, to help explain absorption of acoustic energy and electromagnetic radiation in crystal structures, the peizolectric effect is not one of them.
GK
you are such a strong believer in the Beltist explanations. And my thanks to Rick for carrying on.
When you apply an electrical current to a quartz oscillator, what do you think happens? The quartz is essentially electrically non conductive. The field emanating from the wire creates an oscillation (mechanical) in the quartz crystal. The piezo effect does not only work in one direction with mechanical pressure effecting a voltage change, and the possibility of a reversal can not occur.
So therefore the analysis is simple emf fields create a mechanical movement in a piece of quartz and, if that crystal is allowed to move, that energy is dissipated as heat by the motion of the crystal. Frankly I don't know where you got the acoustical energy part, because I frankly do not remember ever stating that.
I've actually spoken to a couple of PHD's and done some minor research into the subject, nothing extensive, but a simple search through Google will probably yield similar findings.
Stu
Stu, I appreciate your tenacity, but suggest you take your own advice on this and research electromagnetic absorption in crystals. FYI, my undergrad thesis involved atomic mechanisms in crystal structures.You've spoken to some PhDs? Excellent Appeal to Authority! :-)
~ Cheers
that topaz has a 'hole' in its crystal latticework which makes it possible for it to absorb electrons and also possibly change color?
Stu
Let me say this about that - I have studied and played around w/ crystals for a long time, esp. with respect to audio applications. As you know, I have at least 4 products (Brilliant Pebbles) that involve crystals of many types. These products operate via electromagnetic absorption as well as vibrational control, depending on application.
So the hole in topaz acts like an artificial nucleus? Reminds me of something....oh, yeah, the Intelligent Chip. :-)
GK
Hi Geoff,
With respect to "...help explain absorption of acoustic energy and electromagnetic radiation in crystal structures, the peizolectric effect is not one of them."
Since the piezoelectric effect describes the coupling between the E field and distortion of the crystal lattice, how could it fail to be one of them?
If I may take a shot at answering the question you posed for Stu, crystals actually change their physical dimensions when a field is applied. The crystals themselves are very efficient electro-mechanical transducers (hence their high Q) but if they are mounted in a lossy medium they transfer some of that mechanical energy to it which ends up as heat. Thus the answer is 'both'.
Rick
PS: I don't have a clue how effective they are in this application.
But, PE *doesn't* describe the coupling between the E-field and the distortion of the crystal lattice. Has nothing to do with it. That's what I've been arguing against. PE decribes *only* the connection between mechanical force/pressure (such as squeezing) and electrical *voltage* produced by crystal.
You must look elsewhere to describe the connection between E-fields and the crystal lattice, I'm afraid.
Your argument that crystals change their shape is a strawman argument, and is irrelevant.
~ GK
It distorts the lattice which produces an electric field across the crystal. And it's bidirectional. The voltage you refer to is a quantification of the electrostatic potential of that field.
Don't forget that these things are insulators so no current flows through them, all the work is done via E field. They are much more akin to capacitors than batteries.
The spark that you get from your zerostat or stove lighter is a result of the E field inducing a charge differential into nearby metal which can cause a momentary current to flow through a circuit that connects them. They then have an opposing charge which reduces the field. At least on the zerostat you can hear and feel the piezo element deform further when the discharge occurs as you keep a constant pressure on the handle.
Rick
...."squeezing" being the mechanical thing, not the E-field thing. :-)
GK
But, 'tis the squeezing that makes the E-field thing! And vis-versa.
A squeeze can produce results that are just electric...
Rick
The original discussion (between Unclestu and me) was centered on absorption of electromagnetic fields (EMI/RFI) by a crystal. When I used the term E-fields, I was referring to Electromagnetic fields, not Electric fields.
Errr,
The "electro" in electromagnetic is an E or electric field. One and the same, in the flesh. So I think we're talking about the same thing.
I was reading your exchange with interest because it had never occurred to me that a piezoelectric element could be employed to reduce an electric field in this manner. Again, I've no idea how effective it would be but it's an interesting concept and seems theoretically valid to me. Just odd...
Rick
The electromagnetic field I am referring to is the EMI/RFI that Unclestu claims is *absorbed* by the quartz crystal. The electric field you are referring to (I hope I'm not putting words in your mouth) is the result of squeezing the crystal mechanically -- an electric charge or field or voltage. I.e., the piezoelectric effect.
"The electromagnetic field I am referring to is the EMI/RFI that Unclestu claims is *absorbed* by the quartz crystal. The electric field you are referring to (I hope I'm not putting words in your mouth) is the result of squeezing the crystal mechanically -- an electric charge or field or voltage. I.e., the piezoelectric effect."
They're the same thing, just in reverse. Think of old ceramic phono cartridges (Motion > Electricity), think of ceramic piezo tweeters (Electricity > Motion).
Rick
Let me get this straight. You're saying that if the piezoelectric effect explains why a voltage is produced when a crystal is squeezed, then the inverse piezoelectric effect must be the explanation for EMI/RFI absorption in a crystal? That is one big strawman argument you got hanging out there, Rick.Geoff
But I did say that I think it may be true in the case that Stu described, which makes it interesting indeed.
By the way, having received your deleted post I looked up strawman argument to make sure that I understood it. Thank you for providing me with what I reckon is an example.
If there is even a possibility that this works I am interested in learning more about it, that's all.
Don't know it all...yet.
Rick
I agree, what works works, explanation optional. I wrote my paper on crystals for audio applications about 6 years ago for my own entertainment.
Geoff
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