Talk:Electromagnetic induction/Archive 2

Archive 1

Archive 2

Grammar

The phrase "many kinds of device" is currently used in this article. The grammar of this phrase is that the kinds are many and are therefore plural, while the notion of a device is not "many" and is therefore singular. Therefore it is ungrammatical to write "many kinds of devices". — Cheers, Steelpillow (Talk) 08:36, 15 August 2014 (UTC)

Given the context of the sentence, the author's intent is that more than one device makes use of this technology; therefore, the correct word here is "devices." The key clue to this understanding is the modifier "have," rather than "has" in the verb "been invented." "Have been invented" is the plural form of the verb "been used." Had the author typed "has been invented," then the correct word would have been "device." Aasarsak (talk) 21:01, 20 March 2015 (UTC)

No. It is the many kinds of device that have been invented. A single kind replicated would not be plural in this context. — Cheers, Steelpillow (Talk) 21:05, 20 March 2015 (UTC)

The noun being acted upon by the verb in this sentence is "device." The verb conjugation is plural; therefore, the noun which it modifies must also be plural - hence, it should be "devices." Aasarsak (talk) 03:40, 21 March 2015 (UTC)

I believe that in the sentence in question, device is the object of the preposition of. I would go with device singular.Constant314 (talk) 03:50, 21 March 2015 (UTC)

Weberian Approach

According to the linked Weber electrodynamics article, "[t]he theory is widely rejected and ignored by contemporary physicists, and is not even mentioned in mainstream textbooks". So what is the justification for including it in our article? Especially without any critique. SpinningSpark 09:31, 19 April 2015 (UTC)

I have demoted it to See Also. — Cheers, Steelpillow (Talk) 11:21, 19 April 2015 (UTC)

I do not think it belongs in the article even as an Also link.Constant314 (talk) 14:12, 19 April 2015 (UTC)

Fair enough. I think its historical interest deserves a See Also link somewhere, so I have moved it to Classical electromagnetism because Electrodynamics redirects there. — Cheers, Steelpillow (Talk) 14:46, 19 April 2015 (UTC)

flux linkage in a multi-layer coil

If a multi-layered coil is wound around a ferromagnetic core, is the flux linked with the wire in the innermost layer the same as the flux linked with the wire in the outermost layer? — Preceding unsigned comment added by Thecoolsundar (talk • contribs) 09:07, 28 April 2016 (UTC)

It depends what you mean by "the same flux". Provided the windings are tight and have equal turns, yes the flux accounted for in each layer will be the same amount. However for n layers, each will account for 1/n of the total flux through the core. Like cutting up a cake - different pieces but all the same size. I don't think this is worth adding to the article though. — Cheers, Steelpillow (Talk) 10:01, 28 April 2016 (UTC)

For almost all practical purposes, yes. If you are being mathematically exact, the outer layer sees a little less flux. It depends on the shape of the core and the space between the layers. Based on nothing, I would guess that the difference is on the order of parts per million. Constant314 (talk) 13:37, 28 April 2016 (UTC)

Scope of this article

What is the scope of this article?

I claim that the scope of this article is everything to do with electromagnetic induction, Faraday's laws, Maxwell-Faraday equation, generators, eddy currents, the history of electromagnetic induction and how electromagnetic induction and relativity interrelate. Faraday's law (in any sense) is actually formally a subset of this one. This is an encyclopedia article in an encyclopedia, and hence must cover it encyclopedically, which is to cover the topic from all sides. This is the main topic for the area. You can summarise more or less detail, but this topic is the most general, and is the main one.

Does anyone seriously disagree with that? If you do, please even try to explain how knowledge of electromagnetic induction doesn't cover it.GliderMaven (talk) 14:11, 5 June 2014 (UTC)

Makes sense to me. Coverage can be shortened on any given topic if there is a main article to link to, but it needs to be present here. — Cheers, Steelpillow (Talk) 21:44, 5 June 2014 (UTC)

I though the general view was that this article should cover everything to to with EMI, but in a mainly non-technical way, suitable for the general reader. If all the aspects you name above can be treated in a way that is not too technical for the general reader then they should all be in here. I would leave most of the maths and detailed discussion of EMI and relativity to other articles and add more in the way of practical applications here.

The maths and details should be covered in other articles. Martin Hogbin (talk) 16:33, 6 June 2014 (UTC)

Eh... "everything" is too large. Or could be too large. Not quite sure how large is your everything, but there's a lot of things related to EM induction that fall outside of the scope of the article, IMO, so we need to use restraints about dropping the less-relevant stuff (e.g. advanced inductor design, e.g.). You're quite right about Faraday's law being a subtopic of EM induction, but it's a subtopic so large that it needs to summarized here (EMI article), and detailed there (FL article). We also need to greatly simplify and visually illustrate the current summary of FL in this article, because it's way too obscure for anyone but people who already know what FL is. I've outlined what the scope of the article should be above, now it's just a matter of actually making edits so the article falls in line with the outline. Headbomb {talk / contribs / physics / books} 05:00, 24 July 2014 (UTC)

Gave the article a good trim. There should now be much less math, and a much stronger focus on the phenomena, and we now should be able to see the forest. Headbomb {talk / contribs / physics / books} 19:41, 19 May 2016 (UTC)

Faraday's law and relativity - Feynman’s comments

I’ve been examining Feynman’s comments on the two phenomena. He says, “We know of no other place in physics where such a simple and accurate general principle requires for its real understanding an analysis in terms of two different phenomena.” I believe that his comments are being misapplied. The book is not a reference book; it is not even a text book. It is a transcript of lectures for sophomores. As a teaching device, Feynman occasionally makes intentional incorrect statements which he fixes later. I believe that this one of those cases. When you shift to the frame of reference of the moving charge, v x B disappears in the force equation but E’, the transformed E-field, has an added component of v x B, so that the force experienced by the moving charge, in its frame of reference, is given by F=qE’. In other words, the principle of force on a charge requires for its real understanding an analysis in terms of one phenomenon and special relativity. Constant314 (talk) 15:48, 21 May 2016 (UTC)