Talk:Polarization density

message: I added a new section to indicate that the simple velocity equation that relates free charge density and free-charge current density does not hold for bound change density and bound current density. If anyone has any comments, please let me know. Elee1l5 (talk) 18:13, 30 September 2008 (UTC)
replies: text: Sorry, your addition is just wrong.  Even for free charge, it is perfectly possible to have a nonzero free current and a zero charge density.  You just need to have equal and opposite densities of positive and negative charges moving at different velocities, and there will be a net current.  The only relationship between the free current density and the free charge density is the continuity equation, which is equally true for free or total (free+bound) charge.  —Steven G. Johnson (talk) 03:44, 1 October 2008 (UTC)

text: Your addition incorrectly stated the relationship between free charge density and current density, as I explained; expressing the free current density as the free charge density times a velocity is only true under very restricted circumstances.  Nor is it true that the bound charge density can never be associated with a velocity.  For example, if you have relatively immobile ions that are polarizable by displacing the valence electrons with an applied field, then the bound current density in an oscillating field can indeed be related to a velocity of the (oscillating) bound electrons.   Your attempt to draw a firm distinction here is well-intended, but wrongheaded. —Steven G. Johnson (talk) 02:11, 2 October 2008 (UTC)

text: If you define the bound charge density as the divergence of the polarization density, then you should define the free charge density as the divergence of the electric field---in which case it is zero in a neutral wire.  If you are willing to break the free charge density up into a sum of components moving in different directions, then there is no reason not to do the same for the bound charge.  Ergo, you are still wrong.  Anyway, to avoid wasting more time on discussion here, go find an authoritative reference that you think backs you up before arguing more. —Steven G. Johnson (talk) 02:05, 24 October 2008 (UTC)
thread_title:  Relation between bound charge and bound current 

message: Along with new information I've introduced two new sources: [Irodov, I.E.. Basic Laws of Electromagnetism. Mir Publishers, CBS Publishers & Distributors, 1986. ] and [Matveev. A. N.. Electricity and Magnetism. Mir Publishers. 1986.]. I've included a new section dealing with new expressions derived from the definition of the vector P which allows one to introduce and prove Gauss's Law for P from which, in turn, we can obtain the expression of the bound charge density \rho_b related to  shown below in the article (the fact that that equation is a derivation was not apparent). I've also included the proofs for both statements.
In the case of the proof of Gauss's Law, I will upload and insert an image I made showing how one gets the distances d1 and d2 in terms of cosθ and the volumes dV1 and dV2. I'm just waiting for the autoconfirmed account to do so.
Only the first paragraph of the section Relation between P and E in various materials dealt with the case of isotropic dielectrics. I created two subsections here and extended the information about P and E for those types of dielectrics. The relation between surface charge density and polarization is dealt at the end of this subsection. Hence, I've deleted most of the part named Bound Charges since the information there was put into other sections. 
I reorganized the section Polarization density in Maxwell's equations. I thought I'd be appropriate to place it below, once the differential form of Gauss's Law for P is shown. In this way, where the relation between D, E and P comes from is much more apparent. I did nothing with the section Polarization ambiguity.
EDIT: There is an issue about how to defined the vector P among the contributors and among somecited/noncited authors (see comments above). That includes [Irodov] and [Matveev]). To avoid ambiguity I've written the definition as it appears in Matveev's book, which also keeps coherency with the definition using differentials that already had the article.
EDIT 2: Today I've included the image that was lacking in the proof of the flux of P (:.
This is the first time I edit something here, so please let me know whether I did something wrong. 
I keep a copy of the original article before my editions. Just in case...
Joqsan (talk) 10:01, 3 July 2015 (UTC)
thread_title:  Inclusion of Gauss's Law for '''P'''. 

message: To avoid confusion with V used for the electric potential? cӨde1+6 LogicBomb!  22:43, 6 November 2015 (UTC)
thread_title:  Change dV to dTau? 

message: Substituted at 03:10, 30 April 2016 (UTC)
thread_title: Assessment comment

message: Under "Relationship between P and E" for homogeneous, isotropic dielectrics the next equation popps up: Qb = - X/(1+X) . Qf. But electric susceptibility (X) has a positive value, and therefore Qb is negative! How can an amount of charge be negative???  — Preceding unsigned comment added by Koitus~nlwiki (talk • contribs) 20:31, 21 February 2020 (UTC)
thread_title:  A negative amount of bound charges???