Talk:Magnetic field

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Should "magnetic influence" redirect to this article?[edit]

The phrase magnetic influence appears in the first sentence of this article (after which influence does not appear again in the article). A search in Wikipedia on "magnetic influence" redirects to "Magnetic pistol". Maybe "magnetic influence" should redirect to here? Sdc870 (talk) 23:53, 19 March 2019 (UTC)

The target should definitely not be magnetic pistol, a pretty obscure subject. I tried Googling "magnetic influence", and the top few hits were to some huckster called Dani Johnson. After which the next hit was Magnetism. So maybe that's the best choice. RockMagnetist(talk) 02:42, 20 March 2019 (UTC)

Maybe it needs to be marked as "magnetic influence (physics)" [though have not found it mentioned in textbooks] to differentiate it from this definition: (2009) magnetic influence. In: Manutchehr-Danai M. (eds) Dictionary of Gems and Gemology. Springer, Berlin. https://doi.org/10.1007/978-3-540-72816-0 :

"a believing that magnetite or magnetic power promotes the user to be straight forward, reality oriented, etc."

Also, right now, the Magnetism article does not address 'magnetic influence' directly, so it would be necessary to modify that article, if redirected there.

Sdc870 (talk) 09:51, 21 March 2019 (UTC)

I don't think such information would be appropriate on that page. A disambig page would be better. RockMagnetist(talk) 14:39, 21 March 2019 (UTC)

That is also what I was trying to suggest with "magnetic influence (physics)" (but I do not know how to make a disambiguation page). My other point was that right now the Magnetism page does not provide clear information about "magnetic influence (physics)". Did not mean to imply that the superstitious meaning should also be discussed. Sdc870 (talk) 15:00, 21 March 2019 (UTC)

"Magnetic pistol" isn't a terrible target choice for Magnetic influence, which is a common term for a class of naval weapons that are activated by magnetic fields. All 3 of the existing links to that redirect are correctly retargeted to magnetic pistol. There would be no pointto creating a parenthetically disambiguated redirect. VQuakr (talk) 15:53, 21 March 2019 (UTC)

Yes, the more I look into this the more I am leaning towards that point of view. In a search of uses of the term in Wikipedia, almost all refer to the military use. In physics articles, it's just a vague term that should probably be replaced by a more precise term. RockMagnetist(talk) 16:10, 21 March 2019 (UTC)

The expression has been used in non-military scientific texts for over 100 years: examples of the use of the phrase ‟magnetic influence" in physics journal articles, but more or less impossible to find in textbooks. Perhaps the word "influence" has to be removed or defined in the first sentence? Sdc870 (talk) 17:13, 15 April 2019 (UTC)

This seems to me to be an example of overdefining of terms ("redirect overkill"). Looking at the links given, I don't see that the term has a specific meaning, but as RockMagnetist says is a vague term whose meaning varies by context. Making it redirect to a specific article is implying a specificity of meaning that it doesn't have. I'd suggest deletion. --Chetvorno^TALK 12:11, 16 April 2019 (UTC)

I think a conversation about what to do with the redirect should be moved over to its talk page (or maybe Wikiproject Physics). As far as this article is concerned, we should begin by delinking it and then come up with a better wording. RockMagnetist(talk) 15:00, 16 April 2019 (UTC)

Correction: it isn't linked. I don't know why I thought it was. RockMagnetist(talk) 15:01, 16 April 2019 (UTC)

(copied this discussion to Talk:Magnetic influence#What should the target of this redirect be?)

Alternative names???[edit]

"Magnetic field" and "magnetizing field" are NOT alternatives for H. These are just the names "we" gave to these physical phenomena. H is a DESCRIPTION of these phenomena, but it's not the phenomena themselves! — Preceding unsigned comment added by Koitus~nlwiki (talk • contribs) 14:20, 4 June 2019 (UTC)

Are you proposing a change in wording? If so, where? RockMagnetist(talk) 16:52, 4 June 2019 (UTC)

Let's call H the magnetic field and B the effective magnetic field, depending on the medium. — Preceding unsigned comment added by Koitus~nlwiki (talk • contribs) 12:26, 17 February 2020 (UTC)

The both H and B are casually called the magnetic field in reliable sources. However, when reliable sources make a distinction between them, H is called magnetic intensity and B is called magnetic flux density. Constant314 (talk) 13:11, 17 February 2020 (UTC)

Manipulation[edit]

Shaping of magnetic fields?? It seems there exists technology that allows to shape magnetic fields. Setenzatsu (talk) 22:34, 9 June 2019 (UTC)

Since ferromagnetic materials like iron have greater permeability than air, magnetic fields preferentially pass through these materials, so magnetic cores of iron and ferrite are used to guide magnetic fields. Materials of even greater permeability like mu-metal are used for magnetic shielding, which conducts magnetic field lines around areas in which magnetic fields are not wanted. --Chetvorno^TALK 23:46, 9 June 2019 (UTC)

A mess[edit]

This Wikipedia article is a rambling, confusing, badly written hodgepodge that can only be understood (and that only maybe) by someone who already has a PhD in physics. It is worthless to the uninitiated, yet the uninitiated are those who you want to use Wikipedia as an information source. — Preceding unsigned comment added by 108.36.71.119 (talk) 22:44, 19 March 2020 (UTC)

Thank you for the feedback. I pretty much agree, although I am not criticizing the editors who wrote this article; this is just a difficult concept to explain to nontechnically educated readers, more difficult than Electric field. But as you say I think the majority of people coming to this page will be general readers who just want a simple explanation of magnetic fields in ordinary language, and this article could use some improvement on that score. --Chetvorno^TALK 18:18, 20 March 2020 (UTC)

B and H are never the same![edit]

Even in a vacuum, B and H are NOT the same. These are two different entities! Why do you think they have different names? — Preceding unsigned comment added by Koitus~nlwiki (talk • contribs) 12:24, 17 February 2020 (UTC)

It doesn't say they are the same. The sentence in the introduction says: "In a vacuum, $\mathbf {B}$ and $\mathbf {H}$ are the same aside from units..." In a vacuum the relation between them is

\mathbf {B} =\mu _{0}\mathbf {H}

, where

\mu _{0}=4\pi \cdot 10^{-7}\approx 0.000001257

is a unit conversion factor.

\mathbf {B}

and

\mathbf {H}

are vector fields, so this sentence is saying that at any point in a vacuum, the

\mathbf {B}

and

\mathbf {H}

vectors have the same direction and their magnitudes are proportional, with the magnitude of B equal to 0.000001257 times the magnitude of H. --Chetvorno^TALK 01:15, 20 March 2020 (UTC)

You state that " $\mathbf {B} =\mu _{0}\mathbf {H}$ ", so you've proved that they are not "the same aside from units", their magnitudes are proportional, not the same. How can you state that any two vector fields are the "same" without them both sharing the same magnitudes and directions for each of their constituent vectors? --Benjamin J. Crawford (talk) 14:43, 20 May 2020 (UTC)

Just to note that I have now edited the article accordingly. --Benjamin J. Crawford (talk) 16:11, 20 May 2020 (UTC)

An American and a Canadian are standing side by side. For the American the temperature is 68°F, while for the Canadian it's 20°C. Are they experiencing the same temperature? Suppose that temperature was labelled τ in Fahrenheit and T in Celsius? Would they now be different entities? Or are they the same aside from units? RockMagnetist(talk) 17:06, 20 May 2020 (UTC)

It is possible to have a unit system where the permeability of free space is unity. Constant314 (talk) 17:43, 20 May 2020 (UTC)

@RockMagnetist "Would they now be different entities?" - Yes. It would be correct to say that they both describe the same temperature, but it would be a stretch to make the statement that they are the same, aside from units. It's important for this to be unambiguous. In its original form, it was easy to read it as

\mathbf {B} =\mathbf {H}

(except for units), which is simply false. In the same way that in your example τ=T would be inaccurate. Fundamentally they have different magnitudes, and a scaling algorithm which needs to be applied. Benjamin J. Crawford (talk) 17:51, 20 May 2020 (UTC)

Anh Duc Wiki -3

Sunday, May 31, 2020