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Author Topic: Why a permanent magnet does not lose magnetism when magnetizeing iron/ferrite  (Read 7157 times)

Low-Q

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Webby1 had an excellent question. Why does permanent magnets not lose magnetism after magnetizing another magnetic material over and over again?


I passed this question to Physics Forums where I'm a member.


I got his answer:
"Magnets don't give part of their magnetism to the other object when they magnetise it. So they lose nothing.


When a piece of unmagnetised material is placed next to a magnet, the flux in the magnet may actually increase. This is the principle of the keeper that we used to use with our old iron magnets: a piece of unmagnetised high permeability iron is placed across the poles of a horseshoe magnet or two pieces across the ends of a pair of bar magnets. This ensured that during storage there was a high flux through the magnet aligned in the direction that keeps the domains correctly aligned, especially near the poles.
So when an ummagnetised material is placed near a magnet's pole , it does nothing that would demagnetise the magnet. The unmagnetised material gets some flux through it and when the magnet is removed, some of the flux remains, depending on the remnance of the material.
The magnet temporarily enjoys a higher flux level and reverts to its original level when the other material is removed. The process can be repeated indefinitely.
If the magnet is placed near another magnet with like poles together, the flux is reduced. When the other magnet is removed, it may return to its former level, but it may be permanently reduced, depending on the strength of the other magnet and the properties of the material of which it is made (coercivity.)
Since Nd magnets are pretty strong, it would take another stronger Nd magnet to demagnetise it. As you found, the Nd magnet being much stronger than the ferrite, was able to demagnetise it and even remagnetise it in a different orientation. This is because the Nd is strong enough to produce a reverse field in the ferrite when the magnetic field strengths are added.


Reference https://www.physicsforums.com/threads/magnets-and-demagnetization.886071/

forest

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What about the magnet attached to the fridge ? Does it work ?

Low-Q

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What about the magnet attached to the fridge ? Does it work ?
I have made these fridge magnets stronger by placing a neodymium on them for a short second.
Fridge magnets do not work, the are just components that is stuck to the fridge because they're hungry... :D


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forest

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In other words : does magnetization require energy to be spent ? I believe, yes and I believe it needs it continuously to fight against gravity.

lancaIV

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                    cobalt(AlNiCo),neodymium,samarium,cerium,(Lanthaniden) and radioactivity conversion:

Why a permanent radiactive material decay does not lose magnetism when magnetizing iron/ferrite or
probably also non-ferrite !

Low-Q

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In other words : does magnetization require energy to be spent ? I believe, yes and I believe it needs it continuously to fight against gravity.
You believe, but do you KNOW?
When you hook up your clothings for the night, is it energy that keeps them hanging there over night, or is it a counterforce that keeps them there?
So many confuse force with energy. As long the magnet sticks to the fridge, and do not move, work is not done, nor any energy involved  ;)


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lancaIV

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I believe yes,there is the need of energy to become two materials bonded,up this moment there is no more need to spend energy (closed magnetic cycle)


                                        on/off-switch magnet
https://translate.google.de/translate?sl=de&tl=en&js=y&prev=_t&hl=de&ie=UTF-8&u=https%3A%2F%2Fworldwide.espacenet.com%2FpublicationDetails%2Fbiblio%3FDB%3DEPODOC%26II%3D0%26ND%3D3%26adjacent%3Dtrue%26locale%3Den_EP%26FT%3DD%26date%3D19971106%26CC%3DDE%26NR%3D19706659A1%26KC%3DA1&edit-text=

ageofmagnetizm

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Magnetic fields of a permanent magnets depends on coincidence of spins of electrons of atoms of a magnet. This coincidence
depends on alignments of magnetic domains (sort of crystals) inside of a magnet. When a magnet is engaging other ferromagnetic
block - then electrons of a block tends to align its spins with applied magnetic fields causing that magnetic domains rearrange
to align its magnetic poles with attracting poles of applied magnet. This cause magnetization of ferromagnetic block.
While, during magnetization - magnetic domains of applied magnet remain unchanged as its magnetic fields do.
For demagnetization of a permanent magnet - it is necessary to apply other, stronger magnetic fields which will repeal poles of
a magnet - then its magnetic fields will begin rearrangement so that magnetic domains will have theirs magnetic poles attracting
magnetic poles of a stronger magnet. Once that magnetic field of a ferromagnetic block are weaker than fields of a permanent magnet -
then domains of a magnet remains unchanged, and domains of a block change...

verpies

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Ask yourself a question:
"Why an ideal shorted energized coil does not lose magnetism when magnetizing iron/ferrite ?"

Low-Q

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Ask yourself a question:
"Why an ideal shorted energized coil does not lose magnetism when magnetizing iron/ferrite ?"
An ideal coils that has no resistance at all, will have solely current flowing through it all the time.
Electric current cannot carry energy by its own, so there is no energy to loose. In order to get energy, you must involve voltage.
Current is the medium, and voltage is the pressure. In a normal coil you must apply "pressure" to keep the electrons flowing through the coil. While an ideal coil without resistance, there is no need for pressure to sustain the electron flow.


Magnetizing an object does in other words not involve energy, but the normal non-superconductive coils used to magnetize magnets will use energy because the coils isn't ideal, and need voltage to sustain the flow of current.


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conradelektro

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Re: Why a permanent magnet does not lose magnetism when magnetizeing iron/ferrite
« Reply #10 on: September 24, 2016, 12:01:18 PM »
When you hook up your clothings for the night, is it energy that keeps them hanging there over night, or is it a counterforce that keeps them there?
So many confuse force with energy. As long the magnet sticks to the fridge, and do not move, work is not done, nor any energy involved  ;)
In other words : does magnetization require energy to be spent ? I believe, yes and I believe it needs it continuously to fight against gravity.
I believe yes,there is the need of energy to become two materials bonded,up this moment there is no more need to spend energy (closed magnetic cycle)

These questions and answers point to a real mystery according to my unimportant opinion.

Similar situations can be found in the atom. Does spinning the electron around the nucleus require energy? Does holding the protons and neutrons together in the core require energy? Also, does keeping the earth in the orbit around the sun require energy? Or does it require energy to hold objects together which have the opposite charge?

I probably read all the standard answers in the scientific literature, but I am not satisfied. It all sounds to me like a circular argument (like the argumentative proofs that god exists). Yes, I seem to know the difference between energy and force, but still.

It is the question, whether keeping up a field (magnetic field, electric field, gravity, week and strong nuclear field) requires energy?

There are some speculations that the energy to keep up the known fields comes from the "zero point energy" (whatever that is https://en.wikipedia.org/wiki/Zero-point_energy).

If you go down to the very small (quarks, gluons) the question arises, is there something tangible? The answer seems to be that quarks come and go, are only there a fraction of time. Well, does it require energy to create and to destroy quarks many times per second?

http://www.pbs.org/wgbh/nova/blogs/physics/2014/11/what-is-the-shape-of-a-proton/
http://www.desy.de/news/news_search/index_eng.html?openDirectAnchor=829

Citation: Instead of a marble, it seems, a proton is a kind of “stew”: the up and down valence quarks are like the biggest chunks, but other ingredients combine to produce the total flavour. Those ingredients include gluons—particles that act as a binding “broth”—along with pairs of quarks and antiquarks. Antiquarks are the antimatter partners to quarks, so they don’t pair stably with their matter counterparts. Nevertheless, in the high-energy environment inside a proton, they are constantly created and destroyed along with their partners, in a process that contributes to the total behaviour of a proton.

Generally speaking, nothing is there all the time, everything comes and goes many times per second (very crudely put). Fortunately, everything comes and goes at different instances, therefore we have the impression that something is there all the time (again very crudely put).

I hope you are confused enough to see a mystery. Not only is the keeping up of fields a mystery, the existence of everything (quarks) seems to be hazy.

I think that the answer (which has not yet been found) is in the very small (subatomic realm) and in the very big (cosmological scale). Something very big (on a cosmological scale) provides energy for the very small (keeping up of fields, creation and destruction of quarks).

Greetings, Conrad

Low-Q

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Re: Why a permanent magnet does not lose magnetism when magnetizeing iron/ferrite
« Reply #11 on: September 24, 2016, 01:06:58 PM »
These questions and answers point to a real mystery according to my unimportant opinion.

Similar situations can be found in the atom. Does spinning the electron around the nucleus require energy? Does holding the protons and neutrons together in the core require energy? Also, does keeping the earth in the orbit around the sun require energy? Or does it require energy to hold objects together which have the opposite charge?

I probably read all the standard answers in the scientific literature, but I am not satisfied. It all sounds to me like a circular argument (like the argumentative proofs that god exists). Yes, I seem to know the difference between energy and force, but still.

It is the question, whether keeping up a field (magnetic field, electric field, gravity, week and strong nuclear field) requires energy?

There are some speculations that the energy to keep up the known fields comes from the "zero point energy" (whatever that is https://en.wikipedia.org/wiki/Zero-point_energy).

If you go down to the very small (quarks, gluons) the question arises, is there something tangible? The answer seems to be that quarks come and go, are only there a fraction of time. Well, does it require energy to create and to destroy quarks many times per second?

http://www.pbs.org/wgbh/nova/blogs/physics/2014/11/what-is-the-shape-of-a-proton/
http://www.desy.de/news/news_search/index_eng.html?openDirectAnchor=829

Citation: Instead of a marble, it seems, a proton is a kind of “stew”: the up and down valence quarks are like the biggest chunks, but other ingredients combine to produce the total flavour. Those ingredients include gluons—particles that act as a binding “broth”—along with pairs of quarks and antiquarks. Antiquarks are the antimatter partners to quarks, so they don’t pair stably with their matter counterparts. Nevertheless, in the high-energy environment inside a proton, they are constantly created and destroyed along with their partners, in a process that contributes to the total behaviour of a proton.

Generally speaking, nothing is there all the time, everything comes and goes many times per second (very crudely put). Fortunately, everything comes and goes at different instances, therefore we have the impression that something is there all the time (again very crudely put).

I hope you are confused enough to see a mystery. Not only is the keeping up of fields a mystery, the existence of everything (quarks) seems to be hazy.

I think that the answer (which has not yet been found) is in the very small (subatomic realm) and in the very big (cosmological scale). Something very big (on a cosmological scale) provides energy for the very small (keeping up of fields, creation and destruction of quarks).

Greetings, Conrad
To answer the question "It is the question, whether keeping up a field ([/font]magnetic field, electric field, gravity, week and strong nuclear field) requires energy?"[/font]
Yes, it requires energy to keep up a magnetic field. I do not know the answer to the other. This energy comes ultimately from the sun. Heat is the reason why electrons spins around its nucleus. If you remove all heat, and the magnet drops in temperature to 0K, the magnet does not longer act like a magnet.You can cool down a magnet with the cooling spray that holds approx -50°C, and the magnet is so weak that even a neodymium magnet can't stick to the fridge door. When the temperature increase, the magnetism comes back.
You can also heat up the magnet untill it reach the Curie-temperature. The actions in the electrons will then be so violent that the order will collaps and never be able to recover. This is almost equivalent to a pile of nails. You can order them in upright position so all nails point vertically. Then you can see how much you have to shake the table before everyone falls back in a chaotic pile of nails.


Beside of this you're into something we call string theory I guess. But be careful to put the label "God" to everything you don't understand. I'm sure there is a rational explanation to everything. "God" is just an excuse to not digg deeper into physics and its inner workings.


Vidar

lancaIV

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Re: Why a permanent magnet does not lose magnetism when magnetizeing iron/ferrite
« Reply #12 on: September 24, 2016, 02:30:21 PM »
                                                                                       in-? off-? topic
https://translate.google.de/translate?sl=de&tl=en&js=y&prev=_t&hl=de&ie=UTF-8&u=https%3A%2F%2Fworldwide.espacenet.com%2FpublicationDetails%2Fbiblio%3FDB%3DEPODOC%26II%3D19%26ND%3D3%26adjacent%3Dtrue%26locale%3Den_EP%26FT%3DD%26date%3D19770825%26CC%3DDE%26NR%3D2644927A1%26KC%3DA1&edit-text=
   
(uups,I see and read a really bad machine translation !)


but epo.org own translator is not better,cause by bad original paper description to e-copie transduction
http://translationportal.epo.org/emtp/translate/?ACTION=description-retrieval&COUNTRY=DE&ENGINE=google&FORMAT=docdb&KIND=A1&LOCALE=en_EP&NUMBER=2644927&OPS=ops.epo.org/3.1&SRCLANG=de&TRGLANG=en

                                       reverse method (not from the translation,from the magnet treating !) ?