Talk:Relative permittivity

message: Can anyone talk about the effective dielectric constant which is used for computation in microstrip?
:You can find alot of usefull information here and here. This information should be included in the microstrip article, and this discussion should be moved there. Karol 06:54, 14 October 2005 (UTC)
thread_title:  Mirostrips (section title added) 

message: The article says that "dielectric constant" is only used for the static relative permittivity.  Historically, I believe this was true, but in present usage it is commonly used for the frequency dependent relative permittivity.  Just Google "dielectric constant frequency" if you don't believe me.
Because the definition in the article does not match present usage, I'm marking it with the disputed tag as I don't have a chance to fix it right now.
Arguably, the most unambiguous thing would be to have two pages, one on relative permittivity for the frequency-dependent relative permittivity tensor, and one on static relative permittivity for the electrostatic relative permittivity (what the current "dielectric constant" article is about).  Both of them would mention "dielectric constant" as a common synonym, albeit a possibly ambiguous one.
—Steven G. Johnson 16:44, 8 August 2007 (UTC)
replies: text: Okay, I've moved the page to have an unambiguous title, and clarified the situation of the term "dielectric constant" with a few references to demonstrate its ambiguity and obsolescence.  It still feels like we should have a main page on relative permittivity with most of the definitions etc., with this page just as a smaller special case.  But it's fine for now, I guess.  —Steven G. Johnson 18:36, 9 August 2007 (UTC)
replies: text:  The page now says "Second, while in most modern usage "dielectric constant" refers to a relative permittivity[7][9], it may be either the static or the frequency-dependent relative permittivity depending on context." But, but ... the title of this page is 'relative permittivity', whilst the first line explicitly states it is only about 'static relative permittivity'. IMHO the usage with dielectric constant, whilst having some potential for confusion, is arguably better than what is said here about relative permittivity? This article implies that 'static relative permittivity' is always implied when 'relative permittivity' is encountered on its own, and that when talking about 'frequency-dependent relative permittivity' one must always refer to it in full. I don't think everyone follows those rules? Aarghdvaark (talk) 10:57, 19 April 2010 (UTC)

text:  I noticed that despite strong language in this article differentiating between "dielectric constant" and "relative permittivity" and having dielectric constant link to that very statement, the confusion expressed here is still highly persistent throughout Wikipedia articles.  Aside from that, dielectric constant is still very common jargon in the electric engineering industry, used interchangeably with relative permittivity.  I even corrected two instances where the term was still 'improperly' used in this same article.  If the chosen logic is to link dielectric constant to a simple statement of its ambiguity and obsolescence, then "relative permittivity" or "static relative permittivity" should be substituted anywhere that "dielectric constant" is presently used in any article for consistency.  Perhaps it would actually be more correct if usage is ambiguous infrequently versus nearly every link for that term contradicting its usage? 66.195.220.180 (talk) 21:11, 8 June 2016 (UTC)
thread_title:  Nowadays, people use "dielectric constant" for the relative permittivity at any frequency 

message: In the tablle, there's standing:
 (La,Nb):(Zr,Ti)PbO3	500,6000
what number should this be? 5,006,000 or 500,600 or 500.6000 or what? PLease fix!  —Preceding unsigned comment added by 88.217.34.60 (talk) 14:04, 6 November 2007 (UTC)
thread_title:  (La,Nb):(Zr,Ti)PbO3 

message: User:Brews ohare keeps trying to insert the following unsourced claim, which is original research:
:Contrariwise, departure of a measured εr from 1 is evidence that the measured medium is not "vacuum".
The problem with this claim is that it implies that it is possible to measure the linear permittivity of a putative vacuum, which is not possible unless you have a reference vacuum to compare against.  (This is equivalent to the impossibility of measuring the speed of light in a vacuum, which is impossible because the speed of light in vacuum defines the meter.)
Brews has been fighting on Vacuum permittivity to get his original claim included, see Talk:Vacuum permittivity, and has been inserting similar claims (or claims that imply his claims) on other pages such as this one.   As has been pointed out on Talk:Vacuum permittivity, there are multiple references that state unequivocally that the linear relative permittivity of a vacuum is one by definition of the units, and is hence not a measurable quantity (like the speed of light in vacuum); Brews has been unable to provide any references to the contrary.
—Steven G. Johnson (talk) 14:52, 19 February 2008 (UTC)
replies: text: PS. Please respond to this on [[Talk:Vacuum permittivity], so that the same discussion does not get repeated in multiple places.  —Steven G. Johnson (talk) 14:54, 19 February 2008 (UTC)
replies: text: I will respond further on Talk:Vacuum permittivity; however, I wish to note here that this is a misunderstanding of my position on the matter.Brews ohare (talk) 15:00, 19 February 2008 (UTC)
thread_title:  Don't include original research 

message: What is the dielectric constant of Rice Husk Ash? 210.187.49.65 (talk) 00:53, 3 March 2008 (UTC)
thread_title: Rice Husk Ash

message: what is the dielectric constant of 
a) dry earth (or sand)?
b) wet earth (or sand)?
Thunderbird2 (talk) 08:10, 8 May 2008 (UTC)
thread_title:  dielectric constant of earth or sand 

message: Hey, 
I just wanted to point out that conjugated polymers have dielectric constant from 1.8 to 6 and only polymers with giant polarization have 100000. Just read a first page of the reference (nr. 3) provided...
Therefore I recommend correcting from "6-10000" to "1.8-6 up to 100000".
All the best.  —Preceding unsigned comment added by Mrtransient (talk • contribs) 14:18, 7 May 2009 (UTC)
thread_title:  Small mistake in the table of dielectric constants 

message: There must be something wrong with the approximate value of the constant k in this paragraph, since k is not just a number but has units.--91.3.122.84 (talk) 19:24, 7 September 2009 (UTC)
thread_title:  Lossy Medium - constant k 

message: SI units for relative permittivity are not listed, and if it's dimensionless then this should also be stated.  Preferably early in the article so as to be easy to find.  I would do it myself, but I can't determine it with enough confidence.  —Preceding unsigned comment added by ThorFreyaSaturn (talk • contribs) 02:53, 11 April 2010 (UTC)
replies: text: Added to the lead. Relative permittivities are always dimensionless. Materialscientist (talk) 04:26, 11 April 2010 (UTC)
thread_title:  Units not Listed 

message: Will this be right if added at the end of title section? Thanks in advance.
:The commonly known "like-dissolves-like" principle could be useful here, as the probable reason for the discrepancy is the specific interaction between the oxygen atoms, as the THF could be treated as a homologue of water.
--Esmu Igors (talk) 19:15, 19 January 2012 (UTC)
thread_title:  In: Chemical applications 

message: Why is the measurement of permittivity more relevant in relative permittivity than it is in permittivity?  On the face of it it seems to be a counterproductive move. SpinningSpark 12:12, 13 September 2013 (UTC)
thread_title:  Proposed merge of [[ Permittivity#Measurement]] 

message: "...permittivity is the amount of energy stored in the material per unit voltage applied to the electrodes"
Really? The energy stored in a dielectric is proportional to V2 just to start off with, and the constant of proportionality depends also on the form factor of the capacitor.  I believe the correct relationship is given in terms of energy per unit volume and field strength as,
:W= 1/2 \epsilon E^2
I suggest removing the sentence altogether as it is not summarising anything in the article (even incorrectly) so does not belong in the lede.  Also, the word "similarly" at the beginning of the next sentence should go, that is not similar at all, and if we delete this sentence the compararand has gone. SpinningSpark 17:52, 9 June 2014 (UTC)
thread_title:  Lede accuracy 

message: Folks,
I'm worried about the table of constants, I am not sure thy are correct. Can we please take it down, and assemble it one citation at a time precisely specifying at what frequency range we're operating? --Frozenport (talk) 05:28, 16 November 2015 (UTC)
replies: text: There is no need to take it down altogether, it can be worked on where it is.  An additional column for frequency of measurement might be helpful, and perhaps another explicitly for references, which will make it clear what exactly is not referenced.  By all means take out any unreferenced lines that seem dubious, but the table is much more likely to be worked on and improved where it is than it would be hidden on the talk page. SpinningSpark 14:33, 17 November 2015 (UTC)
replies: text: For one, polarizable liquids, such as water, have very high dielectric constant at low frequencies, when the molecules can follow the field, but not so high when they can't.  Many materials commonly used as dielectrics don't have this change.  For such liquids, a low frequency (DC limit) and high frequency (microwave to optical) region would be useful.  For finer detail, users should find a better reference, with more accurate frequency dependencies.  Gah4 (talk) 01:39, 12 November 2018 (UTC)
thread_title:  fact check the table of constants? 

message: Substituted at 04:07, 30 April 2016 (UTC)
thread_title: Assessment comment

message: Anyone have sources for the dielectric constant of paper? I cannot find that value (k=3.85) anywhere else on the web.
Jsmith7342 (talk) 11:47, 7 February 2017 (UTC)
replies: text: Paper used to be a common dielectric for capacitors, so should be somewhat known, but otherwise, the composition of paper is variable enough that it won't be easy to find a specific value. Gah4 (talk) 01:40, 12 November 2018 (UTC)
replies: text:  First Google Books hit I saw came up with many specific values - you have to pick which kind of paper you mean, and the moisture content, density and frequency all affect it.  Table 1 on page 348 of "Handbook of Physical Testing of Paper Vol. 2"  (CRC Press, 2001 ISBN 0203910494,) says printing paper at 2.3% moisture content over a range of 0.1 to 200 kHz has a dielectric constant of 1.4. Lowest given is filter paper at 1.33, highest is 2.86 for cotton cellulose paper. Table 19 on page 4-30 of "Reference Data for Radio Engineers" says "royalgrey paper" has a constant of 3.30 at 60 Hz. "Standard Handbook For Electrical Engineers 11th Ed " ( which I am slowly retyping into the WP in its entirety) says on pages 4-173 and 4-174 that the constant for paper is a function of the density of the paper. Paper in HV cables has a constant around 2.25 at power frequency and moderate temperature.  So, 3.85 sounds on the high side. We should probably show a more typical value and make a note of the wide range possible. --Wtshymanski (talk) 15:58, 14 November 2018 (UTC)
thread_title:  Sources for table? 

message: There is discussion in coaxial cable on changing from dielectric constant to relative permittivity, so I came here to see what it says.  Physics books that I know, old and new, all call it dielectric constant.  I note references for the name change in engineering and chemistry, but not physics.  I also note that the table is still labeled as dielectric constant.  I might wonder about the WP:COMMONNAME?  Gah4 (talk) 02:06, 31 October 2018 (UTC)
thread_title:  dielectric constant or relative permittivity? 

message: There is a compound with a relative permittivity of a million. 
This compound has a wikipedia page wherein it says that something in the year 2000. 
And I'm not sure but it could contain the element chromium. 
And be made by mixing multiple compounds together in air ar high temperature of between hundreds and thousands of degrees centigrade. Sadly I can't find the page back. 
81.241.94.171 (talk) 06:42, 18 January 2019 (UTC)
thread_title:  Compound with relative permittivity of a million missing 

message: Dear fellow Wikipedians. 
There needs to be a dedicated Wikipedia page that's a list of relative permittivities. 
A separate page that's just about this commonly used electrical property in engineering. 
And This page should then be referenced in the current Relative Permittivity page. 
Both in the see also section and with the short table of relative permittivities.
81.241.94.171 (talk) 06:47, 18 January 2019 (UTC)
replies: text: I suppose so.  Though there are a lot of materials that could go into such a list.  Just about every compound in "The Handbook of Chemistry and Physics" could go in.  (I don't remember now, does the handbook list it?).  For many materials, there is a strong frequency dependence.  Also, many materials (paper, concrete, glass) are variable enough that it is hard to find a single number. Gah4 (talk) 08:53, 18 January 2019 (UTC)
thread_title:  List of permittivity page 

message: The article says  Coulomb force between two point charges.  Seems to me that it could be two line charges, or any other shape that one can calculate from theory. Gah4 (talk) 22:46, 5 December 2019 (UTC)
thread_title:  ''Coulomb force between two point charges'' 

message: At the beginning of the article, it says: "Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum."
The higher the relative permittivity is, the higher the field will be in the medium. The sentence implies the opposite, as it compares the relative permittivity to a measure of decrease.
Just as absorbance would be a decrease of light intensity. This sentence is extremely confusing. 129.69.48.110 (talk) 12:54, 13 July 2021 (UTC)
thread_title:  Confusing sentence 

message: I propose to replace the table with a data table for common compounds' relative permittivity. Here are few sources that can be used as a starting point (please don't extract data manually): Google: Dielectric Constants pdf AXONOV (talk) ⚑ 08:34, 25 July 2022 (UTC)
thread_title:  Data page 

message: The dielectric constant (ok, relative permittivity) of water at frequencies low enough for the dipoles to follow is about 80.  They can mostly follow up to microwave frequencies, which is how microwave ovens work. In ice, they can't follow so easily because of the crystal hydrogen bonds, so it should be less. Also, ice absorbs microwaves less well, complicating defrosting. The optical index of refraction of ice is about 1.31, so the dielectric constant at optical frequency, square of index of refraction, is about 1.7. Gah4 (talk) 04:04, 4 April 2023 (UTC)
thread_title:  Ice at microwave and optical frequencies 

message: For polar liquids, low frequency means that the dipoles can follow the changing field, and high frequency means that they can't.  I usually use "high frequency" to apply for optical frequencies, but others seem to have a different idea. In any case, ice should be closer to 1.7 at optical frequencies.  It is always the square of the index of refraction, as long as that doesn't always mean optical frequencies. Gah4 (talk) 06:55, 19 April 2023 (UTC)
replies: text: Good observation.  The current source presumably is restricted to observations in a range of radio frequencies, and the permittivity of ice might be expected to change significantly below or in the microwave region.  Perhaps we should find a way to qualify the wording: "low frequency" and "high frequency" are largely undefined here.  —Quondum 11:55, 19 April 2023 (UTC)
thread_title:  high frequency