It is possible that you may have confused some of your readers here by
the careless editing of your reply.
Your post gives the impression that it may have been me who wrote the
above account of receiving a radio station signal with metal fillings.
I should like to make it clear that it was not.
I have never heard, nor have I ever claimed to have heard, any radio
signals coming from any of the fillings that I have ever had in any of
The account of the experience which you have replied to above was
written by RP.
Having said that, I should add that I have no reason to doubt that
RP's story is genuine.
It is well known that radio signals are attenuated by metallic
objects, and there is no scientific reason that I know of for
suggesting that metal amalgam dental fillings can be considered exempt
from the laws of nature.
The following is from "Frank", who writes the digest for the Yahoo
newsgroup bioelectromagnetics (you'd have to be a member to access
"the old saw about people receiving radio stations from fillings in
teeth is not a hoax. occassionally the composition is such that it
creates audible sound. Have never had it myself but have met two
people who had it and it was possible to actually hear it with a small
. for the most part, they don't have it long.
they go back to the dentist and get it fixed. needless to say dentists
don't advertise this.
Keith P Walsh
I want to know what to do to receive frequency modulation rather and
amplitude modulation. I can only take so much talk radio and country music.
And of course, would this affect the nerves in people's heads, ie, you pick
up a FM station playing Uncle John's Band (long version).
The mere fact that orange juice would light up my nervous system and
produce the reflex action of spewing what was left across the kitchen. I
didn't have that problem for more than a few days. I'm now 100% ceramic,
even the dentist can't tell the real from the fake. It's nice to be able
to sink your front teeth into an Eskimo Pie and chase it with a sip of
scalding coffee :)
I see Robert could NOT answer the questions as usual.
Rather dense, he is.
What is*your* position on the safety of amalgams, Robert?
What is *your* position on the electromagnetic properties of typical dental
I see that lolly could not answer the questions as usual:
What is your position on Keith Walsh's inability to muster the courage
to ask the physicists at his local college/university his questions
about determining field characteristics and induction of electrical
potential in amalgam dental fillings?
Why have you not urged keith to ask the physicists at his local
college/university to answer his questions?
What is your position on Toxic Shock Syndrome and tampooooooooons?
The field which generates voltage is the magnetic field. (Any
electric field present automatically counts toward the voltage)
So Yes, any changing magnetic field or electromagnetic field which
is changing will induce some voltage. The question is
how much? To maximize the effect, your would have to generate
a field with the maxium rate of change of the magnetic field,
per unit area possible, I would guess probably cutting perpendicualr to
one of the filling faces, (if the filling is seen as rectangle) as it
cuts through the filling.
However there is another way of generating a changing magnetic
field, which is, in fact an electromagnetic wave. EM waves travel
through space with their amplitude, (which includes Electric and
magnetic fields that point perpendicular to each other) constantly
changing, so as the wave passes through an area it generates a changing
magnetice and electric field. But there is
another effect. In the vicinity of atoms EM waves may obey what is
known as the photoelectric effects, which means that the wave is
suddenly absorbed completely and it's energy is converted to
voltage/current that way as well.
Predicting the exact effect of either a magnetic field or Em wave
on a filling is a difficult task requiring solving differntial
equations and setting boundary conditions, and applying probably
antenna theory for an EM wave.
However you could make some approximations, for example you know
that for a magnetic field , whose amplitude is perpendicular to
a metal sheet, the voltage in any closed circuit in the sheet will
equal the change in flux in the enclosed circuit , times some factor
which takes into account, the material properties of the sheet. The
physicists on sci.phys can help you to solve this problem.
For an EM wave you can use an energy argument. Since you should
be able to compute the energy of an EM wave, and the amount of
EM wave energy passing through the area of the filling, you can
estimate that the total energy generated by the filling, in terms of
voltage times current in whatever circuit it is in, cannot be larger
than this amount of energy. The paper you cited did mention an
intruiging fact however, which is that some of the EM energy near the
filling which passes through the mouth might also be aborbed, so you
could ask not just how much voltage is induced in the filling but in
the vicinity of the filling. Maybe this effect is significant in some
cases and maybe not.
For Em radiation wavelength will be the key since the filling will
act as an antenna. YOu could ask someone experienced in antenna theory,
(either a physicist or an electical engineer specializng
in antennas) how to compute this. They can acutally solve the problem
using computer software.
For a pure magnetic field, the main effect will be both it's magnitude
and how fast it changes. An MRI , might in fact be good for this, the
magnitude is certainly very large, but you would have to see how
quickly the field changes, and determine for how long it is changing.
By the way, the US congress and indeed legislatures around
the world are constantly changing their laws and statutes.
But which laws have never changed in the the last 100 years?
Answer: Maxwells laws! (gravity was modified after 1905)
By the way "Dave", a few weeks ago our fellow newsgroup contributor
billkatz wrote this:
"Amalgam is a metallic compound but because of the high resistance of
amalgam, it cannot truly be classified as a conductor. "
This appears to directly contradict what you are saying with regard to
amalgam fillings being conductors.
It looks as if one of you must be mistaken.
Is it you or is it him?
Keith P Walsh
PS, I'd guess that it's him.
No it doesn't.
It simply allows (deliberately) for the fact that after a long time
looking and asking the right questions I have not been able to find an
experimentally determined value for the electrical conductivity (or
resistivity) of a typical dental amalgam.
And I think it shows that my own scientific thought process is perhaps
more rigorous than yours.
Would you yourself describe amalgam dental fillings as "conductors"?
And, if so, would you be able to quote an experimentally determined
value for the material's electrical conductivity - measured in siemens
per metre - (or its electrical resistivity - measured in ohm-metres)
in support of it?
Keith P Walsh
Robert's not good at answering questions.
He can't answer the below ones either.
What is*your* position on the safety of amalgams, Robert?
What is *your* position on the electromagnetic properties of typical
dental amalgams, Robert?
Much better than Keith. I see that you still refuse to urge keith to
pose his questions to the physicists at his local college/university.
Why is that? Are you afraid of the answer or is it that you know that
keith will never do anything that would crumble his theories?
Your wrong. There is a world of difference between can't and won't.
Learn that difference.
Do you think tampons should be forbidden for sale as they cause more
deaths per year than mercury poisoning?
What is your position on the 30000 children who die every day of hunger?
Asking the right questions? Who have you been asking? Certainly not the
Physicists at your local college/university. Inquiring minds want to
Please describe the experiments that you have performed or asked to have
performed by legitimate scientists. Please explain your refusal to ask
the physicists at your local college/university for their help in
determining these values.
What scientific thought process is that? What experiments have you
conducted and what were the results? How can you say your "thought
experiments" are more rigourous than mine when yours are just theories
and I have had the actual experiments performed?
I am not about to provide you with any useful info prior to proper
payment for my research.
Wrong, or at least sloppily worded. The frequency of the electromagnetic
field is matched to the frequency of precession of nuclei with magnetic
moments in the _static_ magnetic field.
[snip irrelevant information about nuclear precession]
And even if they did, it wouldn't be relevant. Nuclear magnetic
resonance has nothing to do with whether the radio-frequency part of the
scanning technology induces electric currents in conductive materials.
That's down to Maxwell's equations and Ohm's law.
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