Talk:Solenoid/Archive 1

Alternative definition
A Solenoid is a form of electromagnet. In its simplest construction it consists of a number of turns of conductive wire through which a current is passed. This creates a magnetic field which is concentrated at the centre of the turns of wire. Any ferrous material that is brought into proximity is attracted by the magnetic field. Generally the construction is arranged so that the ferrous material is presented as a plunger within the coil which is free to move in and out and is held out by a spring when the current is switched off.

Much more efficient forms of a solenoid are made by wrapping the turns of wire around a ferrous C shaped core and where the moving ferrous core is T shaped, which when the current flows creates a tight magnetic loop (the T fitting into the C and touching at the lip and bottom)


 * "Much more efficient solenoids are made by winding the coil around a ferrous C-shaped core and using a T-shaped ferrous core. When a current flows, this structure creates a tight magnetic loop, the T fitting into the C and touching at the lip and bottom."


 * Can we get a more detailed description than this? I don't understand from this description.  A link to a picture online would help. - Omegatron 13:21, Aug 2, 2004 (UTC)


 * I agree with the alternate definition, a solenoid does not need to have a metal core. It just makes it stronger. Fresheneesz 06:45, 6 February 2006 (UTC)


 * The definition should also include the usage of the term in chromatin in biology. A form of DNA packing which occurs during interphase. A solenoid in that case is a small packaged coil of chromatin.  —Preceding unsigned comment added by 74.218.108.82 (talk) 19:15, 26 September 2008 (UTC)

Request:
Under each type of solenoid, I would like to see a list of what they are used for and how they accomplish their work (just stating they can move a metal slug doesn't tell me much). From the description given, they *sound* useless, but of course they're used throughout industry, vehicles, etc. I would also like to see references to Fleming's Left Hand Grip Rule and/or Fleming's Right Hand Grip Rule.

Could some one PLEASE clearly explain, how much force in Newton a solenoid exerts on the armature in terms of;

a) Voltage (V) b) Current (Amps) c) Number of Turns d) Air gap (metres) e) diameter of the Coil(metres)

What effect does wire diameter have? What effect does the geometry of the armature have? What effect does the geometry of the core have?

Thank you

thecoolsundar —Preceding unsigned comment added by Thecoolsundar (talk • contribs) 12:24, 14 August 2010 (UTC)


 * I was looking for this too. As you can see, after three years there is still no answer. This is because these 'authors(???)' don't actually understand what they write about. They just have an ego-trip by copying bits and pieces out of books they don't understand. There is a reason why universities forbid to use Wikipedia as a source for anything in student assignements. Wikipedia is useless. — Preceding unsigned comment added by 115.70.177.64 (talk) 14:18, 16 July 2013 (UTC)

The above questions persist because the answer involves some non-linear math, but they are answerable. Try this download: https://www.keepandshare.com/doc18/25385/solenoidmagnetics-pdf-713k?da=y DMohler69.133.97.31 (talk) 00:05, 30 July 2021 (UTC)

Question about induction
Why is "electromagnetic induction" used as the description of the source of the magnetic field? Induction is the production of potential due to flux... it is not the explanation of the creation of the magnetic field.


 * I agree. I deleted tha bit. --Heron 16:27, 28 October 2005 (UTC)

In an electromagnet (having an iron frame and plunger and solenoid coil) the magnetic field from the energized coil "induces" the domains (clusters of atoms) to align with a common polarity thus forming a strong, polarized magnet. The iron atoms themselves have 3 to 4 unpaired elctrons which gives each atom a magnetic polarization and therefore align (due to induction) with reference to the coil's polarity and field strength. When the coil turns off the domains return to random orientations and the strong magnetism disappears. DMohler69.133.97.31 (talk) 20:03, 31 July 2021 (UTC)

An Example of a Solenoid
How about an electric hoist? I wrote a manual for one once. Imagine your "T" as the metal rope and your "C" as the spooling core. Once powered electrically, the magnetism pulls the rope around the core- through one lip, into its own seating/grooves (to prevent tangle/damage- and into the other lip/attached to a heavy object, as if winding thread around a spool, or a vacuum cord around its housing. Imagine, also, the natural reverse/"unwinding" that would occur if you turned the electric off without putting a break on first!... Don't ships use them, to pull objects to themselves and themselves into docks?

Electromagnet
Hello. Isn't a solenoid the same thing as an electromagnet?


 * Not exactly. Electromagnets come in all shapes, not just solenoidal. --Heron 17:19, 10 August 2006 (UTC)

Also, the uses can be different. In common parlance, electromagnet implies an electromechanical use; whereas, solenoids often implies use as an inductor (aka 'choke') e.g. in circuits.--ElectronicsEnthusiast 22:30, 19 July 2007 (UTC)

Shih Shin Technology
Is the following section needed since it doesn't direct the user to anything whithin Wikepdea. IMHO it is a pointless header?
 * This article is about the coil of wire. For Shih-Shin Technology Co., Ltd.(www.shihhsin.com.tw), see Manufacture and Supply Solenoid (mathematics).

Additional: Have requested page be given semi-protection due to repeated spam from the above. --Rehnn83 15:04, 10 August 2006 (UTC)

Picture discrepancy
the picture displayed on the Solenoid article says that it's a bunch of solenoids. The picture displayed on the Electromagnet article is the exact same but says it's a bunch of electromagnets.

Removed "Solenoids in Fiction"
This section doesn't add anything to the topic, so I've deleted the movie trivia. —Preceding unsigned comment added by Special:Contributions/ (talk)


 * Shouldn't this have been disucssed on here first. P.S. Please sign your comments --Rehnn83 08:05, 27 October 2006 (UTC)


 * I've removed it again. This section was so incredibly puerile and incompetent, it was embarrassing to see it in an encyclopedia. &mdash;QuicksilverT @ 00:02, 12 June 2007 (UTC)
 * It may not be the best place to have it but it does warrant inclusion. It is one of those "Cool Sounding" words that Science fiction has effectively hijacked. (E.g. Bessel Equations in Star Trek, Flux Capacitor in Back to the Future). Three of the four links point directly to the Wikipedia Aritcle/section where the term solenoid is used. Feel free to suggest a more appropiate place or wording. -- Rehnn83 Talk 08:27, 12 June 2007 (UTC)

Derivation of magnetic field inside/outside solenoid?
Is the derivation of the field inside and outside worth including? If so, I'm happy to write it up.


 * I think it would be a useful addition to the article --Rehnn83 20:46, 29 October 2006 (UTC)

absolutely yes--ElectronicsEnthusiast 22:23, 19 July 2007 (UTC)

The explanation contains a lot of hand waving, some of which is inconsistent. E.g. in a infinitely long solenoid with no other sources, the field can not vary longitudinally due to symmetry under translations along the solenoid. Aharel (talk) 11:08, 28 October 2013 (UTC)

Revert?
Does anyone else want a revert? A solenoid is a shape, so examples of solenoids, including those in physics and genetics I believe need to be all on this page, and can then be linked to their main article. I don't believe only adding a little blurb about solenoid disambiguation is appropriate here, especially when it isn't a true disambiguation, there is only one other option. Furthermore, Tomjc removed the link to solenoid in mathmatics. I am going to re-add the link to solenoid for mathmatics, and re-insert the information of solenoids in genetics and request the solenoids in genetics page he created be deleted. Any objections? Silver 19:28, 19 March 2007 (UTC)


 * As I have explained in the "talk". The term solenoid CAN refer to the shape of a solenoid or to the physical and tangible "solenoid" used in the physical sciences, ie.

Person 1 - Your drawing looks like a solenoid. Person 2 - It is solenoid in shape, but it does not conduct electricity. It is the model of current genetic explanation of how the histone complex can be further condensed into the solenoid shape. Another model is the "zigzag" model which I have not yet drawn.


 * This is the reason of disambiguation. A person searching the genetic "solenoid" model will be diverted to this page which has no relation to what the person is actually trying to find, HENCE the disambiguation page.

-tomjc


 * I don't think I understand what you are trying to accomplish. One, why did you remove the disambiguation for solenoid in mathmatics? Two, if the page is to be left as it is now, only regarding solenoids in physics, then there should NOT be a disambiguation page, where there is only one other option, the header should read, 'Se also solenoids in genetics and solenoids in mathematics' with both linked appropriately. I think my point is emphasized in that if a person is searching for a solenoid in genetics and they are brought to this page, it now has NOTHING to do with genetics at all. I think then solenoid should directly route to the disambiguation page, where I have readded the link to solenoids in math. Any 3rd party opinions? Silver 23:23, 19 March 2007 (UTC)


 * Hey again, so I've been linking, and prehaps the best way is the main route for solenoid should be a disambiguation page. We should seperate this article to solenoids in physics and solenoids in engineering, and for each to have it's own page in entirety. What do you think? Silver 23:31, 19 March 2007 (UTC)

Look, all I wanted to do was so that if someone were to search on wikipedia for "solenoid", they would go to the disambiguation page, and if they wanted to go to the biological sciences, mathematical, or engineering term for it, I thought it would make it easier. There is no malicious intent behind my edits, and if you really want it to go to the engineering term, so be it. I'm just saying that in the future it's going to evolve in that direction anyways. If I removed a link to the math term, it wasn't intentional. That is all.


 * Wow, I guess we had some miscommunication then, because I think that would be the best option as well. Currently searching solenoid leads to the physics page, but I think it should go to a disambiguation page as well. Also, I think we should seperate solenoids in physics and solenoids in engineering into two seperate pages, but my background is really only in genetics. BTW ty for adding more info about solenoids in genetics, I am just going to categorize and add a stub to it. Silver 13:55, 4 April 2007 (UTC)

Disambiguation
I just found out that a solenoid is also "a space formed by the intersection of isobaric and isosteric surfaces." in Meterorology. www.factmonster.com. Since I know nothing on the subject, I won't add any material regarding this, maybe someone else with more knowledge can. Silver 04:05, 13 February 2007 (UTC)

Some other person wrote - A solenoid is also a biological term. It's a coil of nucleosomes.

This is true, there needs to be information about solenoid in genetics. This page should be changed to first, a deffinition of a solenoid, as it is a shape. Then it's uses in electro-magnetism and where it is found in genetics. I don't think a disambiguation page should be used, as these are not truly seperate topics, solenoid is one shape, found in many places. Silver 04:02, 13 February 2007 (UTC)

clean up
for example, a solenoid does not have to be wrapped around an object, it is not only the physics community that uses the term solenoid - in fact, they are in the minority compared to electrical engineers, &c. --ElectronicsEnthusiast 22:23, 19 July 2007 (UTC)

The derivation section is in need of some clean up regarding accuracy. for example the field outside the solenoid is zero. You could say that the field goes to zero as the distance from the solenoid approaches infinity, but the magnetic field outside the solenoid is crtainly not zero. Also, it does not give the field as a function of x,y,z (or, in cylindrical coordinates), so it's really not a derivation of the field around the solenoid. btw: he differential element is r x j / |r|3, where r x j is the cross product of the vector r and j, r is the vector position of an arbitrary point in space (maybe a different letter than r would be appropriate as r would come up for radius), and j is an infinitessimal current. |r| is the magnetude of the vector r (pythagoran)./

''Yes i was just thinking that

how about changing " A solenoid is a 3-dimensional shape where a coil is wrapped around a central object."

to someth9ing like

"A is solenoid is a 3-dimensional coil." obviously this sentence above needs to be improved but at least its accurate.


 * The problem with that definition is is that a 3-dimensional coil can be called just that, a coil, or a helix. This concept and this page are still horribly misleading and inaccurate. If a solenoid is a shape, which appears in biological and physical constructs and is also a piece of technology that does not have anything in common with the 3-D shape then there needs to be a disambiguation page.
 * Furthermore, currently the second sentence begins "In physics, the term solenoid refers to a loop of wire, often wrapped around a metallic core..." but the first sentence already stated that "A solenoid is a three-dimensional coil." The beginning of the second sentence is redundant and superfluous. The disambiguation page should have a heading called Shape where the definition can be stated and under the heading will be links to all sources that use the term solenoid in reference to the shape, like Genetics. The separate headings along the lines of 'Physics' and/or 'Engineering' and 'Math' can be plan to see. Silver (talk) 08:53, 30 September 2008 (UTC)

World's most powerful solenoid magnet.
The world's largest solenoid magnet is a superconducting magnet used in the CMS experiment at CERN, the European Organization for Nuclear Research. It is 12 meters in diameter, 12 meters long and develops a field of 4 Tesla with a stored energy of 2600 Mega Joules (enough to melt 18 tonnes of gold!) See http://public.web.cern.ch/Public/en/LHC/CMS-en.html —Preceding unsigned comment added by 134.158.138.183 (talk) 12:27, 14 January 2008 (UTC)

etymology
Does anybody know sth about the etymology of the word, is it latin? --Saippuakauppias ⇄ 00:14, 7 November 2008 (UTC)

Readability for non-experts
I just looked up this page to help my daughter with her grade XII physics. It didn't help me, I'm afraid. The writing is too technical and simple concepts that should be relevant are missing. For example, if discussing magnetic fields, shouldn't 'North' and 'South' be referred to? The diagrams are not very helpful, which is I think the main limitation. The second diagram (cross-section view) has no labels and means nothing to somebody who needs a diagram! The third diagram is much too clumsy. It lacks an indication of North. There are no magnetic field lines. The cylinder is so crude that it is possible to see it in the wrong 3D perspective. A good schematic showing what is shown in the historical diagram from a patent would be more helpful.DonaldSHouston (talk) 04:11, 18 December 2008 (UTC)

Incorrect formula
The field inside an infinitely long solenoid does not contain the h term as this page does. In fact there is no case where a finite length solenoid would contain the term is such a simplistic manner. In other words the formula is only tidy when we consider infinitely long solenoids for a good approximation. See http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/solenoid.html  —Preceding unsigned comment added by 80.123.59.201 (talk) 12:40, 5 February 2010 (UTC)

Honda automatic transmission
I heard somewhere Honda uses automatic transmissions which are essentially solenoid-driven manual units, and this avoids the band wear and torque converter waste of a planetary gear automatic transmission. Is this something that can be added to the main page? MWS (talk) 15:20, 1 July 2010 (UTC)

File:Solenoid with 3 loops.png Nominated for speedy Deletion
An image used in this article,, has been nominated for speedy deletion at Wikimedia Commons for the following reason: Copyright violations Speedy deletions at commons tend to take longer than they do on Wikipedia, so there is no rush to respond. If you feel the deletion can be contested then please do so (commons:COM:SPEEDY has further information). Otherwise consider finding a replacement image for this article before it is deleted.
 * What should I do?

A further notification will be placed when/if the image is deleted. This notification is provided by a Bot, currently under trial --CommonsNotification (talk) 09:45, 5 May 2011 (UTC)

Image
Perhaps it's useful to cut the solenoid in following picture and use it here: 91.182.225.132 (talk) 14:39, 21 January 2012 (UTC)


 * Except that these images appear to be posted as a scheme to promote AOC4Studio which offers skp and .dae files "for a small fee." -AndrewDressel (talk) 15:00, 21 January 2012 (UTC)


 * This is another IPsock of who creates bad images of nonsense inventions at Commons, then sneaks them into Wikipedia articles under an anon IP, to make it less obvious. They should all be deleted under WP:MADEUP.  Andy Dingley (talk) 15:45, 21 January 2012 (UTC)

Effective Permeabilty - Citation?
Does anybody have any idea where the formula for effective permeability came from. I've searched all over the internet but haven't been able to find that formula anywhere. — Preceding unsigned comment added by WordsOnLitmusPaper (talk • contribs) 02:41, 13 January 2014 (UTC)

The term "effective permeability" appears in Electromagnetic Devices (by Herbert C. Roters; 1941) on pp. 103-105 and is referred to as µd. It appears in a couple of equations and also appears in the graph on page 105. Roters' example for effective permeability describes a laminated filter choke having a fixed air gap in the magnetic circuit. Such a choke, having variable current and flux components, is used to smooth (to some extent) the ripple of the d.c. output of the rectifier. The incremental permeability of the combined iron and air gap in series is the effective permeability. This book is out of print and very expensive on Ebay; I found a pdf download online some years ago.69.133.97.31 (talk) 14:37, 6 August 2021 (UTC) DMohler 8/6/2021

Equation error?
The equations for magnetic flux density in Finite Continuous solenoids differ from the reference in: https://nukephysik101.files.wordpress.com/2011/07/finite-length-solenoid-potential-and-field.pdf. B_rho and B_z are a factor 2 different- it is as if the definition of L has been changed to half-length instead of length compared with the derivation in the reference. Also a minus sign missing from B_z ? -198.129.218.211
 * Fixed the minus sign. I don't know whether the nukephysik101 source passes WP:RS, but I found no factor-of-two discrepancy. The equations for B_rho and B_z are given in red twice in the nukephysik101 source; the first red instance has 1/2pi in front but an extra 1/2 inside the integral version, while the second red instance near the bottom of the source is written exactly the same as in the article. Rolf H Nelson (talk) 20:32, 19 February 2017 (UTC)
 * I am coding a solenoid just like this as a part of my Ph.D. and I can tell you for sure that the $$A_{\phi}$$ field derived in this article is not correct. I've gone through the reference https://nukephysik101.files.wordpress.com/2011/07/finite-length-solenoid-potential-and-field.pdf and coded it all myself. I can provide proof if need be, but I would suggest replacing the final $$(A_{\phi})$$ formulation with the integral form on page 1 (in blue) because the field distribution from the final A field formulation is not correct. Also, no one really notices that this solution is not valid for $$\rho=0$$. This is the only correct form for $$A_{\phi}$$ in this reference


 * $${A_\phi } = \frac\frac{L}\left[ {\zeta \int_0^\pi {\fracd\phi } } \right]_^$$


 * I thoroughly checked the equations for B_rho and B_z, and I'm now pretty sure that the pdf from nukephysik101 contains mistakes of factors of two. On the other hand, there's a NASA report which I now referenced, which seems fully correct to me. L refers to the full length, both in the article and in the references. So I fixed a missing factor of two in both equations and also changed the minus sign of B_z. This sign needs to differ from the nukephysik101 pdf, because that uses a different ± convention in ζ in comparison to this page and the NASA report. An independent method to check the equations for trivial mistakes is to compare it with a dipole at large distance. In the long run I believe we should not refer to the erroneous pdf but some WP:RS instead. We could add the initial integral equations for B as well, which can be easier verified and might be useful for numerical integration. --Geek3 (talk) 23:19, 22 January 2019 (UTC)

Contradiction
The first paragraph of the article contains this definition for a solenoid:

"A solenoid... is a coil wound into a tightly packed helix"

Two subsequent paragraphs, in the sections "infinite continuous" and "finite continuous" solenoids, each contain this statement:

"Continuous means that the solenoid is not formed by discrete coils but by a sheet of conductive material." Anything fitting this description of a "continuous solenoid" would not be a coil and would therefore fall outside the definition of a solenoid in the first paragraph.

Either "solenoid" needs to be defined more broadly in the first paragraph to include "continuous solenoids", or the sections on "continuous solenoids" need to be moved to other articles.

Gorillasaurusrex (talk) 20:50, 1 August 2016 (UTC)

Solenoid types
This page dosent address push, pull or any other types of solenoids. I feel that this is critical information that needs to bee on this page. — Preceding unsigned comment added by 184.91.254.26 (talk) 21:46, 9 September 2016 (UTC)

Push and Pull Solenoids - Push and Pull solenoids are common catalog items, usually in a tubular construction. They consist of a bobbin-wound coil, steel plunger and cylindrical case and each is similar to the other in construction except that the pull type has means for attaching to the plunger and pulls the attached load toward the solenoid. The push type has a push-pin projecting out of the solenoid to push the load away from the solenoid. Magnetically they are the same; i.e., internally the magnetic field attracts the plunger toward a stator pole piece. Most solenoids do not use magnetic repulsion between the magnetic poles to do the pushing except in rare instances. For instance, the rotary type of U.S. patent 5,337,030 uses both attraction and repulsion of a permanent magnet simultaneously in order to rotate (and is bi-directonal by reversing the coil's electrical polarity). Normal push or pull solenoids move in one direction only upon being energized. A spring or other means is required to move the plunger to its de-energized position.````DMohler 8/5/2021