Relative Permittivity of Water

[TinselKoala]

Well, OK, you make some pretty good points but I still don't think you are completely correct. I've just been looking at specs of many resistivity meters used for water testing, and even the cheap ones for consumer use go into the megOhms/cm range.

[Torana]

Im shocked no ones hauled me over for the balls up on the decimal. The devils in the details people
-Haste- on my part, sorry.
Air            =3MV metre  =3kv per mm
Pure water =30MV metre =30kv per mm
water ??    =24MV metre =24kv per mm
24 - 30kv is acheivable but then if water is converted to gas state (white water),permittivity drops
Air =1.00059   Hydrogen =1  oxygen =1
so again the permittivity of 80 goes out the window. So whats the break down voltage now?
3 kv per mm?
Why publish dielectric strength 24-30MV metre if water is capable of changing state?

Resistivity/conductivity meters use Alternating Voltage at 2 khz or so to avoid the plates polarising the water molecules. why??
What happens when water polarises? what happens when DC is across water?
A simple test using DC across water and measuring current with a regular old multimeter will indicate Resistance of a sample of water. R = V / I

As for inventors using a water cap , are they using pure water?   
If they claim tap or sea water , to classify as a cap it HAS to be non conductive.
Fundamental characteristic of a cap = DC can not get thru

[exnihiloest]

...
24 - 30kv is acheivable but then if water is converted to gas state (white water),permittivity drops

"Water" is the layman term for H2O under liquid state so water permittivity is not the same as water vapor permittivity which is surely near 1 due to a very low density of matter.

...
Resistivity/conductivity meters use Alternating Voltage at 2 khz or so to avoid the plates polarising the water molecules. why??
What happens when water polarises? what happens when DC is across water?
...

A dielectric polarization consists in shifting the electronic cloud around the atom nucleus, along the electric field. With normal conditions and materials this effect is linear. A DC polarization doesn't change the AC polarization thus the permittivity is the same, at least at low frequencies.
The reason for using AC instead of DC is the same as for measuring a capacity (rather simpler with AC than DC) and to avoid chemical reactions of the remaining ions with the electrodes (oxydo-reduction).

A simple test using DC across water and measuring current with a regular old multimeter will indicate Resistance of a sample of water. R = V / I

You forget the redox potentials, depending on the density and type of ions. Even in pure water, there are some H3O+ and OH- ions.
"Water" connected with electrodes is not a pure resistance. U=R*I doesn't apply.

What is your goal? To prove that scientists do not measure correctly water permittivity, by proposing us incorrect methods using not purified water?

[Torana]

Im not trying to prove anyone wrong

fritznien    =P W is non conductive
t koala     =P W has resistivity
exnihiloest= P W is not irrelevant
fritznien   =C meter on air cap...C should go up 80 times    ( it should but it doesnt)
exnihiloest=..purify water,measure permittivity..you can PRODUCE water with meg ohm of R
t koala     =leyden jars  ( the dielectric?)

I agree with all the reply posts , Im questioning relative permittivity of pure water VS every other type of water that goes UNLISTED on the scale.
A leyden jar is an excellent example of a glass dielectric separating 2 water conductors, its 180 degrees opposite to a theoretical water cap which is theoretically pure water between 2 conductors.
Leyden jar is an example of water used in diametrically opposed function to the "cap".
clearly the permittivity scale is isolated to pure water and pure water ONLY.
The more you delve into it,you start to discredit stan meyer or anyone who claims to use tap or sea water as a component,   whats the dielectric value???

I encourage anyone to do a DC test on natural water, if it conducts ,can that conductive liquid be used as a nonconductor between 2 plates and present an open circuit to DC???
...the same DC that was used to prove that it was conductive in the first place..

Simple fact is -A capacitor is an open circuit to DC, test one , anyone can do it.
A capacitor is a high pass filter , it blocks DC,thats why we use them.
Caps are measured in OHMS capacitive reactance not resistance.

Conductance is reciprocal of Resistance
Conductivity / resistivity is shifting into another area of testing

[CompuTutor]

I hate to whack this with the "Simple Stick",
but isn't the real answer so evasive
as to be beyond all confirmability ?

It is the mixed question aspect of all this:
"How long is a piece of string ?"

The data required to answer this
just seems to be missing initially
from the question itself to me...

Raw H2O in a vacuum enviroment,
after a period of natural dissociation
to that vacumm enviroment,
will settle to be a very low value.

But tap water, nature's brook water, nature's pond water, laboratory purified water all lend a span of measurement so wide that the better question might be...why do you want to know ?

Purified water becomes useless as reference once exposed to our atmosphere anyway.

Water in It's own right has a form of memory to each and every substance it has ever come in contact with that to this day no one has yet to completely explain to satisfaction as it is.

So what inert material will this water under vacuum be withheld in for this test ?

If it is a form of plastic, there will be ions to contend with, a glass static charge carriers, etc.

Short of wandering out of our atmosphere into space and popping a couple of probes made of some material that water is not imprinted with to make this measurment, I cannot see this being successfully measured to any degree that could be held as a standard.

Then there is the ubber-amazing non-linear aspect of how water acts when it is used as the dielectric of a water capacitor.

This is awsome, and has caused life-long dedication to the study of this by many...

Sorry for pissin' on the Cherios...