Talk:Insulator (electricity)/Archives/2021

Two topics - should it be two articles

Page seems about insulation materials (very general) and insulator objects (very specific objects from some related applications).

@Light current: made a similar point in 2006. The 2016 archive has : "Insulation v insulators - I hesitate to ask, but should these two subjects have separate pages?--Light current 03:36, 28 March 2006 (UTC)"

Article seems to need more on materials - eg when flexibility, high temperature, or corrosion resistance are needed ? eg what materials are used for insulating wires in high temp aerospace applications, or in down-hole applications hot & deep in drill bores/wells. or to insulate electrical motor windings, or high-voltage transformer windings ? What temperatures can PVC or PTFE be used to ? Gutta-percha, cotton ? - Rod57 (talk) 10:18, 13 June 2021 (UTC)

I've added {{split "suggested that this article be split into articles titled electrical insulation and electrical insulator."

and that this Insulator (electricity) disambiguate between them. - Rod57 (talk) 10:30, 13 June 2021 (UTC)

I'm not entirely opposed, but I think there are actually three terms which need to be defined:

1. electrical insulator - a substance which has a very high resistivity
2. electrical insulator - a component used on utility poles and pylons to support wires, made of a substance which is an insulator
3. electrical insulation - a protective covering for wires and conductors made of a substance which is an insulator

I wouldn't object to splitting off "insulation" into a separate article, but I oppose two separate articles for the two definitions of "insulator". Every time we create two articles with the same name we make it harder for readers to find what they want. And there is plenty of room in the article to cover the two meanings of "insulator", and explaining the difference to readers on a single page is clearer than having two articles. In fact all 3 terms are related, and splitting anything off will entail some redundancy, so as long as there is room it might make sense to cover all three subjects in this article. --Chetvorno^TALK 18:38, 13 June 2021 (UTC)

Why does the insulator insulate ?

Sorry for the stupid question, but actually there's something that seems unclear to me. It is said that the electrons of the insulator are bound to their atoms. Fine. So, these electrons can't access the conduction band to participate to the electric flow. Alright. Still, the conduction band does exist. So, if the electric source injects some electrons on the conduction band of the material, what prevents these electrons from progressing on said conduction band? In other words : why should the charge transfer be due exclusively to the electrons that belong to the material? I miss omething....

Does reading Electrical breakdown help? --Guy Macon (talk) 13:47, 29 June 2021 (UTC)

87.86.104.115 thanks for the insightful question. I agree the article could be clearer. A substance must have intrinsic charge carriers to conduct electricity, in order to maintain electrical neutrality; it can't get them from the source. When an electron in a metal leaves its atom to become a conduction electron, it leaves behind a positive ion so the metal is still neutral. If you attached metal electrodes to a good insulator like ceramic and applied a voltage across them, at the negative electrode electrons would diffuse a short distance from the metal into the ceramic under the influence of the electric field. But because there are no balancing positive charged ions in the ceramic, the electrons would be attracted back to the positive ions they left in the metal, and would form a negative surface charge layer, creating an opposing electric field which would prevent more electrons from entering. --Chetvorno^TALK 15:15, 29 June 2021 (UTC)

thanks both for your prompt replies :)

I had read the article about breakdown, but it didn't really clarify things, because it explains how electrons of the material go from bound to unbound state.

My concern was more about : why don't we just have electrons from the source that circulate on the conduction band?

If I understand Chetvorno's reply, it's related to the fact that an electron leaving the negative electrode would leave an positive charge on said electrode, attracting back the electron (and the ceramic sample getting a negative charge, would repell electrons back anyway).

But I'm sill confused (sorry :D ).

If my electrodes are actually connected to, say, a condensator. The negative electrode is due to an excess of electrons in the electrode (and we have positive ions on the positive electrode side) : the voltage results from this charge imbalance.

So, electrons will reach the ceramic sample.

If they can't move, then I agree that again the electrons "concentration" will equilibrate between the electrode and the sample (locally), and no current occurs. And on the positive side, no electron reaches the positive elctrode, bc there's no mobile electron amyway.

But (that's precisely my concern), if electrons are on the conduction band, they actually can move from the negative to the positive electrode, even if it implies that the ceramic ends-up with a slight negative charge eccess (the condensator wouldn't be able to empty totally, as it would with a metal sample ; but a circulation of part of the electrons would nevertheless be possible).

This is obviously not what we observe, but I don't get what my reasonning is missing.

I hope my explanation of the problem is clear.

87.86.104.115 (talk) 16:54, 29 June 2021 (UTC)