Talk:Relative static permittivity

From Wikipedia, the free encyclopedia

	Portal This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
Stub	This article has been rated as Stub-Class on the assessment scale.
???	This article has not yet received an importance rating within physics.
Help with this template Comments: edit – history – watch – refresh In the 'Practical relevance', the line "If a material with a high dielectric constant is placed in an electric field, the magnitude of that field will be measurably reduced within the volume of the dielectric." is confusing because a material with high permittivity (and thus dielectric constant) should increase the strength of the electric field between two metal plates and thus allow it to hold more charge. This contrasts to materials with smaller dielectric constants which reduce the electric fields. This is used in PCBs to insulate signal carrying conductors from each other. http://www.siliconfareast.com/dielectric-constant.htm (At the bottom). The section should be reworded to properly distinguish between the two applications given its dielectric constant value.

Contents 1 Mirostrips (section title added) 2 Table of values 3 Glass: Index of refraction and dielectric constant 4 Nowadays, people use "dielectric constant" for the relative permittivity at any frequency 5 (La,Nb):(Zr,Ti)PbO3 6 Please provide references for table values... 7 Don't include original research 8 Rice Husk Ash 9 dielectric constant of earth or sand

[edit] Mirostrips (section title added)

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)

[edit] Table of values

I moved the table od dielectric constant values from permittivity, and formatted it a bit. Karol 09:38, 29 November 2005 (UTC)

[edit] Glass: Index of refraction and dielectric constant

Am I the only person who has noticed the discrepancy between the index of refraction n of glass (around 1.5 visible light), and the dielectric constant of glass, usually noted as being greater than 3.8. Since the dielectric constant (for nonmagnetic materials) is n², then one would expect to see a value of 1.5² = 2.25 Can anyone explain this to me? —The preceding unsigned comment was added by 155.92.180.59 (talk) 23:20, 16 March 2007 (UTC).

Your value only applies for frequencies in the visible range. The listed values are for a static electric field. In full, the dielectric constant is a complex, wavelength dependent 'constant'. -- Daan

[edit] Nowadays, people use "dielectric constant" for the relative permittivity at any frequency

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)

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)

[edit] (La,Nb):(Zr,Ti)PbO3

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)

[edit] Please provide references for table values...

The table lists "High Polymers" and "Sodium Nitrate" as very high premittivity materials. I have searched for information on both of these materials and can find no evidence they are. Please provide a reference for these values.

Thanks Elmerfud (talk) 18:31, 14 December 2007 (UTC)

oh yes, and nitrate is NO3- nitrite is NO2- —Preceding unsigned comment added by 131.118.39.101 (talk) 22:39, 14 December 2007 (UTC)

Done. -lysdexia 16:00, 16 December 2007 (UTC) —Preceding unsigned comment added by 68.127.229.114 (talk)

[edit] Don't include original research

User:Brews ohare keeps trying to insert the following unsourced claim, which is original research:

Contrariwise, departure of a measured ε_r 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)

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)

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)

[edit] Rice Husk Ash

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

[edit] dielectric constant of earth or sand

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