Talk:Electrostatic induction

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There is a serious flaw with the mechanism of electrostatic induction as stated in the article "electrostatic induction" where it has been mentioned under the sub-heading "Explanation" viz. "A normal uncharged piece of matter has equal numbers of positive and negative electrical charges in each part of it, located close together, so no part of it has a net electric charge. When a charged object is brought near an uncharged, electrically conducting object, such as a piece of metal, the force of the nearby charge causes a separation of these charges. For example, if a positive charge is brought near the object... the negative charges in the metal will be attracted toward it and move to the side of the object facing it, while the positive charges are repelled and move to the side of the object away from it. This results in a region of negative charge on the object nearest to the external charge, and a region of positive charge on the part away from it"

The statement "while the positive charges are repelled and move to the side of the object away from it" is inconsistent with the Lorentz-Drudze Theory of electrical conductivity in metals viz. the electron sea model which is capable of explaining electrostatic induction, where kernels (the atom with nucleus) having the positive charge remains static (or vibrates) while the electrons move about the crystal lattice. Positive charges cannot move to one end because kernels are not free to move, if it would, then the crystal lattice of the crystal should have changed with electrostatic induction a fact that is experimentally not founded.

Secondly, if protons are assumed to move out of the kernel in the crystal lattice then the conductor's nucleus would be rendered unstable.

Thirdly distortion of the electron cloud (polarization) in the presence of electric field creating dipoles, is not possible because conductors are not dielectrics and has got free electrons.

The best way to explain electrostatic induction is to use the concept of electron density. An explanation is given as under:

An uncharged conductor contains not only equal amounts of positive and negative charges but also has got uniform charge distribution thus it remains electrically neutral under ordinary conditions. Again, a conductor has got a lot of free electrons but the protons (positive charges) in the nucleus of the conductor atoms (called kernels) are not free to move about and when such a conductor is brought near a positively charged body, the electrons in the conductor move towards the positive charge thus, negative charge develops on the side facing the positive charge due to an increased electron density. Because of this movement of electrons from all the areas of the conductor to one side, an electrical imbalance is resulted on the other side i.e. because of low negative charge density the kernels that have positive charges on the other side do not get adequate electron density to remain electrically neutral, thus positive charge develops on the other side of the conductor. Inverse behavior of conductor can be shown in the vicinity of negative charge. Being an important article, I request the author/ authority to review the article for further consideration. — Preceding unsigned comment added by Sevenseas (talk • contribs) 09:57, 6 February 2011 (UTC)[reply]


Positive charges cannot move to one end ... the protons (positive charges) in the nucleus of the conductor atoms (called kernels) are not free to move about

How do you know? It could be a proton conductor. You should really stick to talking about generic "charges" and not make erroneous claim about which charge carriers can or cannot flow in a generic material. 96.224.70.185 (talk) —Preceding undated comment added 20:01, 9 April 2012 (UTC).[reply]

Picture[edit]

The text specifically states "Electrostatic induction should not be confused with electromagnetic induction; both are often referred to as 'induction'.". Nice, because some idiot has still found the time to put up a picture called "electromagnetism" (the same picture the electromagnetism wiki page has)...The REAL Teol (talk) 18:39, 16 May 2011 (UTC)[reply]

inFamous Cole's Induction Grind, would he be using this type of Induction?[edit]

I know I'm using video game physics to propose this question, but the physics used in the game are pretty right on I believe. His ability to Induction Grind on rails though, would he be using this type of induction, or another type of induction that is similar.24.115.153.189 (talk) 02:32, 14 July 2011 (UTC)[reply]

Introducing Electrostatic induction as a WPT technique[edit]

I am still wondering where and how, electric coupling coefficient between dipoles (as the counterpart of coupled coils) as well as it application to wireless power transfer could be introduced. The capacitance matrix Qi=CijVj is introduced in the Capacitance page as well as the ideas of self and mutual capacitance without going any further. A capacitive coupling coefficient is used in Coupling coefficient of resonators but not in the most common way (through the previous matrix coefficients) and with a link to Capacitive coupling where such a formula is not present and even the idea of coupling is ill defined. The best way to clear this situation could be:

- to add a Coupled dipoles and mutual capacitance section in the capacitance page (to keep the symmetry with the Inductance #Coupled inductors and mutual inductance

- to add a few words on the subject in the Capacitive coupling page (I have started the job but it is not finalized yet)

- to add a brief description on the current page on how electrostatic induction is used in WPT applications (through a sentence and a link to the WPT page)

What do you think ? --Henri BONDAR (talk) 14:17, 22 April 2016 (UTC)[reply]

How about putting it in the Wireless power article? You and I discussed this a while back on the Talk:Wireless power page; I hope I didn't discourage you. I think it would be an excellent addition. The only concern I'd have is that, as a somewhat advanced mathematical topic, in the interest of clarity it not be put ahead of the elementary explanations of capacitive coupling. Maybe it could be put in a separate section, not Wireless power#Capacitive coupling? My feeling about your above suggestions is that WPT might be a little too specialized and application-oriented a topic to put in general physics articles like Capacitance, Capacitive coupling, or Electrostatic induction. Just my opinion, of course. ChetvornoTALK 05:45, 23 April 2016 (UTC)[reply]

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"The electrostatic field inside a conductive object is zero"[edit]

The electrostatic field inside a conductive object is zero[edit]

A remaining question is how large the induced charges are. The movement of charges is caused by the force exerted on them by the electric field of the external charged object, by Coulomb's law. As the charges in the metal object continue to separate, the resulting positive and negative regions create their own electric field, which opposes the field of the external charge.[1] This process continues until very quickly (within a fraction of a second) an equilibrium is reached in which the induced charges are exactly the right size to cancel the external electric field throughout the interior of the metal object.[1][2] Then the remaining mobile charges (electrons) in the interior of the metal no longer feel a force and the net motion of the charges stops.[1]

Surface charges induced in metal objects by a nearby charge. The electrostatic field (lines with arrows) of a nearby positive charge (+) causes the mobile charges in metal objects to separate. Negative charges (blue) are attracted and move to the surface of the object facing the external charge. Positive charges (red) are repelled and move to the surface facing away. These induced surface charges create an opposing electric field that exactly cancels the field of the external charge throughout the interior of the metal. Therefore electrostatic induction ensures that the electric field everywhere inside a conductive object is zero.
  1. ^ a b c Cite error: The named reference Purcell was invoked but never defined (see the help page).
  2. ^ Saslow, Wayne M. (2002). Electricity, magnetism, and light. US: Academic Press. pp. 159–161. ISBN 0-12-619455-6.

the article clip above has several problems:

(1) it confuses guass's law and coulumb's law - since both refer to zero and conducting shells.

(2) the graph shows guass's law only but isn't (properly) described by the article

(3) the article talks of opposing charges forming - which is due to coulumb's law and is purely situational: and which is also unrelated to the description (or education) of "E=0 inside conductor" phenomenon

(4) also it said "remaining question". (a) it should not borrow a continued thought from another other section (since that might change) (b) there is no question as to mobility or speed. (c) as i already said, charges that oppose surface charges should not be mentioned because they do not change Qin, or point voltage, nor E=0 inside - nor can the author testify where an when any opposing charges arrange to an extent for which material. the matter of opposing charges does not belong in this discussion.


If the field on a conductor is positive charged no "negative charges" are created to balance. Only when a rubber charged rod (+) influences an un-charged metal sphere does a (conducting sphere) develop opposing charges on each half of sphere (negative charges migrate toward positive of rubber positive leaving the other side of the sphere +, a simple matter of distance and balancing of opposite forces, the electrical pressure is balanced within the mobility constrains of the conducting sphere boundaries). Without any grounding when the rod is taken away, the sphere is again un-charged (it remains uncharged always - but a voltage appears between sides temporarily when the rod is introduced). Put another way: if a "+ charged conductor" were to gain electrons to balance the + charge on the outer sphere with a layer of - charges in more inner layer: the sphere would no longer be a charged sphere; it would be a un-charged sphere because all charges would be opposed and equalled.

E is zero but point voltage is not. The force between like net charge evenly distribute along the outer conductor because it is the easiest path. The e are restricted to the conductor at low charge/voltage to that of air - and to be dispersed that farthest from each other they obviously choose the surface). It is a simple matter of all pushing away from one another and the medium and size they have to work within. E==0 however the electrical potential (Vp) is not zero inside, it is the same as that near the outside of the sphere of course. Anywhere inside (not including center) there is an equal an opposite reaction for distance and number of pushes from that distance: simply put - if all forces are equidistant in a sphere (of any kind, electrical or otherwise), anywhere inside that sphere has an equal push from all sides (meaning E, the net direction of pull, is 0, no direction pulls more than another).

The last two paragraphs are FAR DIFFERENT than the purely mathematical [Gauss's law] which shows net flux "through a conductor" is zero. That is a simple matter that opposing fluxes are not counted and sphere has equal area seen from from both sides.

Another matter that is simply explained of [Gauss's law] is "net flux == Qin/e0". It means simply that if flux are set out like lines on a clock (the number of lines must equal E*A of a point charge in center and cannot change), that of one draws any closed loop of any shape, the number of lines traversed in making the loop is always the same (for clock lines, 12). It is simply a mathematic statement that once drawn the lines cannot "go missing" by choosing any closed loop path.

[Gauss's law] counts amount of area exposed to electric field and should not be confused [Coulumb's law] of electrical force applied to the dynamic situation of electrons taking their easiest path within a (charged) conducting sphere shape.

I wrote the section in question. The above criticism is pretty incoherent, but I think the misunderstanding is that you got the idea this section is about hollow conductive shells. It's not, it's about solid conductors. The shapes in the drawing are meant to represent solid pieces of metal, not hollow sheet metal shapes. Gauss's law can be used with a hollow conductor to demonstrate electrostatic shielding (see Faraday's ice pail experiment) but that is not what this is about. Anyway the section is sourced. --ChetvornoTALK 14:55, 23 July 2020 (UTC)[reply]
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