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Author Topic: Magnet Myths and Misconceptions  (Read 531116 times)

Offline tinman

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Re: Magnet Myths and Misconceptions
« Reply #930 on: January 13, 2015, 03:33:23 PM »
Several have explained and you can easily research for yourself to determine that the lines in a magnetic field diagram each represent a quanta of flux.  You may wish to object that such diagrams aren't helpful to you, but your argument that the archetypical such drawing of the field around a dipole does not fairly represent the flux has been refuted many times over.  The diagrams that you have presented with their figure eight shapes would be somewhat representative of flux density, if the proximity of the lines to the magnet is intended to represent flux density.

The arrows in a magnetic field diagram tell us orientation.  If we place a magnetized dipole in the field that is free to rotate in the plane of the lines, the arrows tell us which way that dipole will align.

When you say physical force, do you mean to say "mechanical force"?  If you do, what mechanical force do you refer to?  Is it the force on some glob of highly permeable material?  Is it the torque on a highly permeable dipole?

I am not a You Tuber.  I don't shoot videos.
Ha,i was just reading your last post,and i like this bit-Quote: Those who think linearly but who do not master the basic skills tend to regurgitate what they are taught without consideration for the fact that mostly correct is not totally correct.

Anyway,back to the question.
Quote
When you say physical force, do you mean to say "mechanical force"?  If you do, what mechanical force do you refer to?  Is it the force on some glob of highly permeable material?  Is it the torque on a highly permeable dipole?

So here is what we need to know in regards to force. What physical structure is it that provides a pulling force between a magnet and say a piece of iron-what reaches out of the magnet to retract that piece of iron back to it(the magnet).

What do you believe these two opposite forces are that can exert a physical force toward magnetically active materials(materials that react to a magnetic fields presence).E.G,are they oppositely charged particals?.

I believe you made reference to the wind not so long back,and how we cant see it,but we can feel it and see it exert a force on tree's-and things like that. But with that,we can fully explain how wind is created,and we can give exact ratio's of what gasses make the air that moves to become wind. So we need the same information about the magnetic fields that form a dipole,and like the wind,the explinations have to be clear and precise to be accepted.

It is all well and good to say-we know the magnetic field is what we think it is,because computors and CRT monitors work the way they do. Well my car has a V8 engine,and that engine provides the needed energy to propel my car down the road at 110kph. Thing is,my mate up the road has a car that also dose 110kph down the road,and his motor is a rotary engine. It opperates on the same principle,but is of a completely different design. Then there is the electric car-altogether different motor design and a different type of fuel,but guess what-it still pushes a car down the road at 110kph.

So before you have the right to dispell anyone's thoughts/theories about magnetic fields,you need to provide absolute information about why and how a magnetic field dose what it dose-explain it as clearly and correctly as we can the wind.

Offline MarkE

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Re: Magnet Myths and Misconceptions
« Reply #931 on: January 13, 2015, 04:14:57 PM »
Ha,i was just reading your last post,and i like this bit-Quote: Those who think linearly but who do not master the basic skills tend to regurgitate what they are taught without consideration for the fact that mostly correct is not totally correct.

Anyway,back to the question.
So here is what we need to know in regards to force. What physical structure is it that provides a pulling force between a magnet and say a piece of iron-what reaches out of the magnet to retract that piece of iron back to it(the magnet).

What do you believe these two opposite forces are that can exert a physical force toward magnetically active materials(materials that react to a magnetic fields presence).E.G,are they oppositely charged particals?.

I believe you made reference to the wind not so long back,and how we cant see it,but we can feel it and see it exert a force on tree's-and things like that. But with that,we can fully explain how wind is created,and we can give exact ratio's of what gasses make the air that moves to become wind. So we need the same information about the magnetic fields that form a dipole,and like the wind,the explinations have to be clear and precise to be accepted.
That wind analogy was not mine. 
Quote


It is all well and good to say-we know the magnetic field is what we think it is,because computors and CRT monitors work the way they do. Well my car has a V8 engine,and that engine provides the needed energy to propel my car down the road at 110kph. Thing is,my mate up the road has a car that also dose 110kph down the road,and his motor is a rotary engine. It opperates on the same principle,but is of a completely different design. Then there is the electric car-altogether different motor design and a different type of fuel,but guess what-it still pushes a car down the road at 110kph.

So before you have the right to dispell anyone's thoughts/theories about magnetic fields,you need to provide absolute information about why and how a magnetic field dose what it dose-explain it as clearly and correctly as we can the wind.
No, when one wishes to argue against established understanding it is up to the challenger to provide convincing evidence.

As human beings we do not have any absolute knowledge.  Philosphers get to argue about such matters while never attaining absolute knowledge anymore than anyone else.   We can absolutely predict with deadly accuracy: static electric, static magnetic, and electrodynamic behaviors to incredibly high accuracies.   That we are able to do so, very strongly suggests that we have a very strong grasp of how the elements interact.  If someone wants to make a dent in the set of beliefs that allow us to do this, then they need to find at least one situation where their new idea makes better predictions, while making equally accurate predictions as established beliefs in all other cases.  It is a very tall order.  So no, I reject the idea that one has to have a fundamental answer to the theory of everything in order to adhere to established scientific beliefs: IE physical laws.  To paraphrase Dr. Sheehan:  "Laws are laws until they aren't."  Come up with a case of where the laws fail.  Then come up with a better answer.

Offline NoBull

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Re: Magnet Myths and Misconceptions
« Reply #932 on: January 13, 2015, 05:59:40 PM »
Bar magnets [one over the other] a few pages back  ,a twist ?? 
Nice example: https://www.youtube.com/watch?v=U9lsaGtRBGc
So you noticed the analogy between turning magnets and turning domains in a soft ferromagnetic.
Too bad TinselKoala did not reply to this message about a similar subject.

Offline allcanadian

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Re: Magnet Myths and Misconceptions
« Reply #933 on: January 13, 2015, 06:32:09 PM »
@Mark
Quote
"Laws are laws until they aren't."  Come up with a case of where the laws
fail.  Then come up with a better answer.
Personally I have found the laws almost always apply however many people have failed to consider the context in which they are applied. For instance a drop of water cannot climb up a wall against the force of Gravity, it is impossible and violates many known laws of science. Yet this is exactly what one scientist did using an engineered material (nano-material) and he did not break any laws doing it. In fact his experiment did not violate any laws but in fact proved them on that scale.

My magnetic bearing is another example and when I told some people I built a 99% passive magnetic bearing based solely on attractive forces they said it cannot be done and violates the laws of science. It doesn't violate the laws of science or Earnshaws theorem because it is 99% passive not 100% and again basically proves the laws but in a completely different context than most would expect.  Thus in my mind it was never the laws which were ever in question but a persons ability to understand the context in which the laws may be applied.
At which point we could go one step further and say the laws we know may always apply however we may never know the infinite number of ways in which the context of there application could change. Almost anything is still possible however it is not a matter of breaking a law but how we interpret and apply it from our own perspective.
The Down wind faster than the wind technology is another perfect example because I didn't see that one coming. I mean I have decades of experience researching and experimenting in aerodynamics but that one caught me completely off guard no matter how obvious it was after the fact.

AC
 

Offline sparks

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Re: Magnet Myths and Misconceptions
« Reply #934 on: January 13, 2015, 06:55:28 PM »
   If the core of the Earth is a plasma and the plasma is spinning would the free electrons comprising the outer sheath of the plasma generate a magnetic field?.   It looks to me like the Earth is nothing more than a little bubble of Sun stuff.   Some plasma, when the plasma sphere of the sun was much larger, that got swirling and became magnetically propelled from a portion of the shrinking plasmasphere of the younger sun.   Now she's cooling off and skinned over with atoms.  The plasma current just happens to be aligned with the surface rotation and meanders independent of the rotation of the atomic stuff on the confining surface we live on.  Periodically the shear zone between the rotating plasma increases in viscosity.  This links the surface with the plasma and aligns the plasma rotation with the surface rotation at various polar angles.

Offline TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #935 on: January 13, 2015, 07:01:19 PM »
So you noticed the analogy between turning magnets and turning domains in a soft ferromagnetic.
Too bad TinselKoala did not reply to this message about a similar subject.
I'll reply now if you like. My statement was a response to another post where it was claimed that storing energy in magnetic fields was inefficient. I replied by stating that in the general case it was actually very efficient and I gave some examples. Then I attempted to agree with the original claim by stating:
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Storing energy by magnetizing  _permanent magnets_ and attempting to recover that stored energy is inefficient.
You responded with a situation that has nothing at all to do with magnetizing permanent magnets and recovering that stored energy, but rather simply shows how moving permanent magnets from one orientation to another within a solenoid stores and recovers energy. You get to do that _once_ in your artificial configuration, then you have to put that energy back in to "reset" back to the mutually repulsive configuration. Try to recover the energy cost from cutting the magnet as in your post, and see how efficient that is!

Offline TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #936 on: January 13, 2015, 07:09:47 PM »
The "We know how wind works" is another false analogy, because ultimately, wind depends on gravity and energy from the sun to operate. Tinman could easily be asking "how does gravity work" or "how does the sun's energy heat the air". Really, he is asking "Why" questions, not "how" questions. We can usually fully describe "how" these things occur and anyone can look up math formulae at whatever level of complexity they desire to describe and calculate just "how" they happen. The deeper question is "why", and there are many such "why" questions at the bleeding edge where science and philosophy collide. Why is there something, rather than nothing?
Good luck with that one.

How does a magnetic field attract a ferromagnetic substance? The formulae are there for anyone to see and compute with. You can even plug the data into your favorite magnetic simulator and calculate just how strong and in what direction the attraction will be, and this is done every day by motor designers, etc. who actually find that their motors etc. behave as the calculations predict. The "how" is understood pretty darn well.  "Why" does this attraction happen? That's a philosophical question, not a scientific one. 

Offline MarkE

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Re: Magnet Myths and Misconceptions
« Reply #937 on: January 13, 2015, 07:33:39 PM »
@MarkPersonally I have found the laws almost always apply however many people have failed to consider the context in which they are applied. For instance a drop of water cannot climb up a wall against the force of Gravity, it is impossible and violates many known laws of science. Yet this is exactly what one scientist did using an engineered material (nano-material) and he did not break any laws doing it. In fact his experiment did not violate any laws but in fact proved them on that scale.
Excuse me I must have missed that particular law.  What is it known as?  Gravity exerts a force.  Set-up a set of conditions where there is more force up than gravity imposes down and things accelerate upward.
Quote

My magnetic bearing is another example and when I told some people I built a 99% passive magnetic bearing based solely on attractive forces they said it cannot be done and violates the laws of science. It doesn't violate the laws of science or Earnshaws theorem because it is 99% passive not 100% and again basically proves the laws but in a completely different context than most would expect.
So either "some people" misunderstood you or they misunderstood the constraints of Earnshaw's theorem.
Quote
   Thus in my mind it was never the laws which were ever in question but a persons ability to understand the context in which the laws may be applied.
People make mistakes all the time, yes.
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At which point we could go one step further and say the laws we know may always apply however we may never know the infinite number of ways in which the context of there application could change.
There is a big difference between an individual misunderstanding a law and whether or not the law is valid.
Quote
Almost anything is still possible however it is not a matter of breaking a law but how we interpret and apply it from our own perspective.
Nature doesn't give a hoot what someone understands.  Physical laws get codified because all efforts to falsify the belief fail.  Laws fall or get modified whenever reliable observation shows that a given law does not hold.
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The Down wind faster than the wind technology is another perfect example because I didn't see that one coming.
A lot of well educated people did not think that it could work.  But there were no laws that it broke.
Quote
I mean I have decades of experience researching and experimenting in aerodynamics but that one caught me completely off guard no matter how obvious it was after the fact.

AC
Individuals make mistakes.  Even SME's make mistakes.  That does not make physical laws into some whimsical smorgasborg that one can choose to ignore.  I remember years ago a debate at between Sean McCarthy of Steorn and a professor of physics, I think at UCD.  Sean McCarthy tried to argue that he was taught that test triumphs theory.  Therefore any test or test claim triumphs theory.  ( Over the years Steorn demonstrated that they very consistently conducted junk tests. )He got handed his head on a plate by the professor.  Reliable experiments drive and challenge theory.  Flawed experiments and flawed interpretations cause temporary distractions, ala N rays.

Offline NoBull

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Re: Magnet Myths and Misconceptions
« Reply #938 on: January 13, 2015, 07:40:20 PM »
You responded with a situation that has nothing at all to do with magnetizing permanent magnets and recovering that stored energy, but rather simply shows how moving permanent magnets from one orientation to another within a solenoid stores and recovers energy.
If you subscribe to the model of a permanent magnets being composed of tiny magnetic dipoles (domains) then it does.
According to that model, the energy stored in permanent magnets is due to the spatial orientation of these domains.
If those domains were allowed to rotate freely (e.g. by exceeding the Curie temperature or cutting up the magnet), then the net magnetic field of a magnet would disappear.

Such disappearance would induce EMF in a coil encompassing the magnet.

You get to do that _once_ in your artificial configuration, then you have to put that energy back in to "reset" back to the mutually repulsive configuration.
Yes, of course.  That's why I asked you about the efficiency of reversibility of such process.

I do not really suggest cutting a magnet up.  Two magnets rotating on a common axis are sufficient to illustrate the process.  They are also magnetic dipoles, just larger...

Offline MarkE

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Re: Magnet Myths and Misconceptions
« Reply #939 on: January 13, 2015, 07:50:03 PM »
If you subscribe to the model of a permanent magnets being composed of tiny magnetic dipoles (domains) then it does.
According to that model, the energy stored in permanent magnets is due to the spatial orientation of these domains.
If those domains were allowed to rotate freely (e.g. by exceeding the Curie temperature or cutting up the magnet), then the net magnetic field of a magnet would disappear.

Such disappearance would induce EMF in a coil encompassing the magnet.
Yes, of course.  That's why I asked you about the efficiency of reversibility of such process.

I do not really suggest cutting a magnet up.  Two magnets rotating on a common axis are sufficient to illustrate the process.
TK will be happy to point to papers on certain EMP weapons that he has in the past that leverage the rapid demagnetization of hard magnetic material by blowing the material up.

The Curie temperature idea could be a fun experiment.  I'd have to ponder a bit on how to perform the experiment safely.  Maybe this can be done by taking an ordinary iron bar as a control and a neodymium magnet as the DUT and placing each successively inside a large diameter coil for thermal insulation and then exposing each to a propane torch.

Offline TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #940 on: January 13, 2015, 08:42:13 PM »
If you subscribe to the model of a permanent magnets being composed of tiny magnetic dipoles (domains) then it does.
According to that model, the energy stored in permanent magnets is due to the spatial orientation of these domains.
If those domains were allowed to rotate freely (e.g. by exceeding the Curie temperature or cutting up the magnet), then the net magnetic field of a magnet would disappear.

Such disappearance would induce EMF in a coil encompassing the magnet.
And would be irreversible without remagnetizing the magnet, and would require an _input_ of energy to heat the magnet. So you have a situation where energy is input to magnetize the PM, then energy is input to heat it past the Curie point to demagnetize it....  does this sound like an efficient process to you?  Don't forget that the induced voltage is proportional to the time rate of change of the change in magnetization. So to get anything much out of the solenoid you have to have all your domains flipping within a short period of time. Good luck doing that with heating past the Curie point.
Quote
Yes, of course.  That's why I asked you about the efficiency of reversibility of such process.
In the situation you describe I doubt if you could reverse the orientation of the two magnets, or half-magnets, by pulsing the external solenoid. As you said, once the magnet-halves have flipped so they are in mutual attraction, very little of their fields "leak" out, so what will the pulsed solenoid's field be acting upon?

Quote
I do not really suggest cutting a magnet up.  Two magnets rotating on a common axis are sufficient to illustrate the process.  They are also magnetic dipoles, just larger...
So you have to put energy in to "c o c  k" the system, then when you release whatever is holding it in the cocked state, the solenoid recovers the energy that you put in in the first place. This may be relatively efficient except for the inevitable electrical losses, just as the ordinary "cogging" of a rotor magnet passing a core is relatively energy-neutral except for eddy current losses and bearing wobble, etc. It also has nothing to do with storing and recovering energy by magnetizing and demagnetizing permanent magnets! Your comparison of this process to the alignment and de-alignment of domains is a real stretch, I think.

Offline TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #941 on: January 13, 2015, 08:59:25 PM »
TK will be happy to point to papers on certain EMP weapons that he has in the past that leverage the rapid demagnetization of hard magnetic material by blowing the material up.

The Curie temperature idea could be a fun experiment.  I'd have to ponder a bit on how to perform the experiment safely.  Maybe this can be done by taking an ordinary iron bar as a control and a neodymium magnet as the DUT and placing each successively inside a large diameter coil for thermal insulation and then exposing each to a propane torch.

Well, I remember posting information about explosively pumped Flux Compression Generators coupled to Vircator emitter systems used to produce EMP. That's a bit different from what you describe here, though. I don't remember talking about fragmenting permanent magnets to recover their energy of magnetization (which after all isn't very great.) In the FCG an _electromagnet_ in the form of a solenoid coil is rapidly and progressively short-circuited by an explosive charge driving a shunt which effectively forces the initial magnetic flux to concentrate into fewer and fewer turns of the electromagnet coil, eventually to be released as a very strong, fast rise-time pulse into the virtual cathode emitter/antenna system which then radiates the energy onto the target. Much of the radiated energy comes from the high-explosive charge that drives the shunt, I think.
http://en.wikipedia.org/wiki/Explosively_pumped_flux_compression_generator
This is another excellent example of how the conventional view of flux lines is used to design, control, and predict the behaviour of real devices that work as their designers intend them to.

I did find one type that uses an exploded magnet as the first "seed" stage to power the electromagnet solenoid second stage (second image below). Most systems that I am aware of use a capacitor bank for the "seed" power to the FCG solenoid stage, though. Again, it is the high-explosive's energy that is converted into electrical energy by the fragmenting magnet within the first-stage solenoid, not the magnetization energy per se.

Offline EMJunkie

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Re: Magnet Myths and Misconceptions
« Reply #942 on: January 13, 2015, 09:27:39 PM »
IMO, the most important research skills are:  1) Critical thinking, 2) The ability to search for relevant existing information, 3) The presence of mind and humility to ask questions.  Somewhere down the list is the ability to personally set-up and conduct experiments.  Many things that we want to know about will be well beyond our individual means to directly research.  Creativity is very useful but it is also down the list.  Those who master the criitical basic skills and are also creative thinkers are able to take jumps where linear thinkers must plod.  Linear thinkers who master the basic skills are equipped to make advances.  Those who do not master the basic skills but are creative can have interesting ideas but are unequipped to sift gems from dross.  Those who think linearly but who do not master the basic skills tend to regurgitate what they are taught without consideration for the fact that mostly correct is not totally correct.

Again MarkE - You have surprised me - I agree!

I don't agree with the numbering of each item but agree these are good guidelines!

1) The ability to search for relevant existing information - Research Skills
2) The presence of mind and humility to ask questions - Intuition - Looking outside the Box!
3) Ability to personally set-up and conduct experiments.
4) Keep things Simple! - Don't over complicate things!
5) Critical thinking - Believe Nothing, Assume Nothing until Experiment proves it! Even then Experiment must be repeatable every time! Check for Experiments that Contradict the first!
6) Documentation!
7) Extension of the above - More Intuition!

This list may not be ideal also but certainly the above is important! Else one will never progress!

Kind Regards

  Chris


Offline MarkE

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Re: Magnet Myths and Misconceptions
« Reply #943 on: January 13, 2015, 09:42:13 PM »
Well, I remember posting information about explosively pumped Flux Compression Generators coupled to Vircator emitter systems used to produce EMP. That's a bit different from what you describe here, though. I don't remember talking about fragmenting permanent magnets to recover their energy of magnetization (which after all isn't very great.) In the FCG an _electromagnet_ in the form of a solenoid coil is rapidly and progressively short-circuited by an explosive charge driving a shunt which effectively forces the initial magnetic flux to concentrate into fewer and fewer turns of the electromagnet coil, eventually to be released as a very strong, fast rise-time pulse into the virtual cathode emitter/antenna system which then radiates the energy onto the target. Much of the radiated energy comes from the high-explosive charge that drives the shunt, I think.
http://en.wikipedia.org/wiki/Explosively_pumped_flux_compression_generator
This is another excellent example of how the conventional view of flux lines is used to design, control, and predict the behaviour of real devices that work as their designers intend them to.

I did find one type that uses an exploded magnet as the first "seed" stage to power the electromagnet solenoid second stage (second image below). Most systems that I am aware of use a capacitor bank for the "seed" power to the FCG solenoid stage, though. Again, it is the high-explosive's energy that is converted into electrical energy by the fragmenting magnet within the first-stage solenoid, not the magnetization energy per se.
Yeah those are the sorts of machines I was thinking of.  Even a modest amount of energy when released quickly enough translates to lots of power. 

Offline EMJunkie

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Re: Magnet Myths and Misconceptions
« Reply #944 on: January 13, 2015, 09:48:35 PM »
@MarkPersonally I have found the laws almost always apply however many people have failed to consider the context in which they are applied. For instance a drop of water cannot climb up a wall against the force of Gravity, it is impossible and violates many known laws of science. Yet this is exactly what one scientist did using an engineered material (nano-material) and he did not break any laws doing it. In fact his experiment did not violate any laws but in fact proved them on that scale.

My magnetic bearing is another example and when I told some people I built a 99% passive magnetic bearing based solely on attractive forces they said it cannot be done and violates the laws of science. It doesn't violate the laws of science or Earnshaws theorem because it is 99% passive not 100% and again basically proves the laws but in a completely different context than most would expect.  Thus in my mind it was never the laws which were ever in question but a persons ability to understand the context in which the laws may be applied.
At which point we could go one step further and say the laws we know may always apply however we may never know the infinite number of ways in which the context of there application could change. Almost anything is still possible however it is not a matter of breaking a law but how we interpret and apply it from our own perspective.
The Down wind faster than the wind technology is another perfect example because I didn't see that one coming. I mean I have decades of experience researching and experimenting in aerodynamics but that one caught me completely off guard no matter how obvious it was after the fact.

AC

@AC - I completely Agree!

Millikan's Oil Drop Experiment! Law still applies but the conditions under which the prior known Laws were applied have now been changed!

I watched a Video online the other day, Earnshaw's Theorem, URL: https://www.youtube.com/watch?v=djPdEsL7EHY

Claiming to disprove Earnshaw's Theorem! However, the distance of the Charged Particles is not taken into account! As Charged Particles get closer together, the Inverse Square Law, actually Inverts relative to Quantum Distance!

So as the Particles move closer together, what was attractive actually becomes repulsive! Due to the Inverse Square Law!

So Laws are still relevant! Only under the conditions they were defined under!

Kind Regards

  Chris