Extracting energy from a permanent magnet

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Avian
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Extracting energy from a permanent magnet

Permanent magnets in some more or less complex arrangement are popular components of attempted "free-energy" and perpetual motion machines.

In articles that try to explain why such machines can't work I often read that there are some machines that appear to actually produce energy, but actually do that by weakening the permanent magnets in them (for example here at the bottom, 2) http://dispatchesfromthefuture.com/2007/07/first_glimpse_of_an_orbo.html)

That seems reasonable at first. A magnetic field does store energy - You have to do some work to set up a magnetic field and the same amount of work (minus losses) can be extracted from it when you collapse it. All coils work on that principle.

I'm an electrical engineer and I'm as aware as anyone that Maxwell's theory doesn't leave any doubts about conservation of energy in such machines. However, can someone explain how you can extract energy from a permanent magnet? I have trouble imagining how this can be done, since this is a time invariant field and you can not access the bound currents that generate it like in a coil. Plus when you demagnetize a magnet you don't actually destroy the field, you only let all the fields of Weiss domains approximately cancel each other.

zalzane
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Re: Extracting energy from a permanent magnet

A magnetic field does not store energy. All particles have a magnetic field, but their arrangement in compounds are usually too random and ecstatic to produce a measurable field.
Permanent magnets, however, have the poles of the particles all lined up, creating a measurable field. Sort of like how sticking a bunch of nanotubes together makes a very strong compound.

EricH
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Re: Extracting energy from a permanent magnet

zalzane wrote:A magnetic field does not store energy. All particles have a magnetic field, but their arrangement in compounds are usually too random and ecstatic to produce a measurable field.
Permanent magnets, however, have the poles of the particles all lined up, creating a measurable field. Sort of like how sticking a bunch of nanotubes together makes a very strong compound.

And yet, having the poles lined up is a higher energy state than having them randomly arranged. Where would you prefer to say that energy is stored?
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zalzane
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Re: Extracting energy from a permanent magnet

EricH wrote:
zalzane wrote:A magnetic field does not store energy. All particles have a magnetic field, but their arrangement in compounds are usually too random and ecstatic to produce a measurable field.
Permanent magnets, however, have the poles of the particles all lined up, creating a measurable field. Sort of like how sticking a bunch of nanotubes together makes a very strong compound.

And yet, having the poles lined up is a higher energy state than having them randomly arranged. Where would you prefer to say that energy is stored?

It's not quite a higher energy state when they are randomly arranged.

Spoiler:
Let the first frame represent the two particles which are facing the same direction.
Let the third frame represent these particles when in close proximity, see how their power is added together

Spoiler:
Let the first frame of this image represent the two same particles, but now they are facing different directions. (up and down)
Let the third frame represent these particles when in close proximity, see how their power cancels each other's out.

Images borrowed from http://electron9.phys.utk.edu/phys135d/ ... /waves.htm

As you can see, the power does not 'go' anywhere, it just cancels the other out.

EricH
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Re: Extracting energy from a permanent magnet

Sorry, I chose the wrong level of detail the first time. Let's see if I can be clearer.

zalzane wrote:It's not quite a higher energy state when they are randomly arranged.

You are correct; indeed, it's a lower energy state when they are randomly arranged.

With regard to your pictures, the assertion I'm going to make is that when two particles have magnetic fields that line up, it will require energy to push the two together (you can see from your pictures that the total magnetic field is larger at that point), and energy will be released when they're separated. Likewise, if the fields are opposite, energy will be released as the two particles approach, and just as much energy will be required to separate them again.

zalzane wrote:As you can see, the power does not 'go' anywhere, it just cancels the other out.

Uh, you really don't want to be using the term 'power' there; the word has a definite meaning in physics, and it's not a vector. 'Field' is better, in this case.
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gmalivuk
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Re: Extracting energy from a permanent magnet

zalzane wrote:A magnetic field does not store energy. All particles have a magnetic field, but their arrangement in compounds are usually too random and ecstatic to produce a measurable field.
Permanent magnets, however, have the poles of the particles all lined up, creating a measurable field.

Yes, and lining all the particles up like that requires an input of energy.
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Avian
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Re: Extracting energy from a permanent magnet

zalzane wrote:A magnetic field does not store energy.

Guys at CERN also thought so, until a faulty coil caused the field of one of their superconducting magnets to collapse and blew a 10-ton machine apart

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Re: Extracting energy from a permanent magnet

Permanent magnets certainly store energy. I would think that you could capture some of this energy by placing a coil around a permanent magnet, and then heating the magnet so that it loses its magnetization. As the magnetic field drops to 0, a current will be induced in the coil. This is probably a dumb way to extract the energy, but it would get you something.
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Re: Extracting energy from a permanent magnet

Avian wrote:
zalzane wrote:A magnetic field does not store energy.

Guys at CERN also thought so, until a faulty coil caused the field of one of their superconducting magnets to collapse and blew a 10-ton machine apart

Wasn't the failure due to breakdown of superconductivity, resulting in massive resistive heating from the current running through the magnet, as opposed to energy stored in the B-field?
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Vaniver
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Re: Extracting energy from a permanent magnet

You, sir, name? wrote:Wasn't the failure due to breakdown of superconductivity, resulting in massive resistive heating from the current running through the magnet, as opposed to energy stored in the B-field?
If I remember correctly, one of the failures was a mechanical failure because they didn't account for the fact that their magnets would be heavier during operation (because of the stored energy) than they were normally. I don't follow CERN that closely, though, and so both my reports and memory can be flawed.

To extract energy from a permanent magnet, move it through a coil of wire. That should work (though you're also recapturing a lot of the energy spent moving the magnet).
I mostly post over at LessWrong now.

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Re: Extracting energy from a permanent magnet

Vaniver wrote:To extract energy from a permanent magnet, move it through a coil of wire. That should work (though you're also recapturing a lot of the energy spent moving the magnet).

If you were capturing energy from a magnet through that process, what energy does the magnet use to recover it's B-field once it's exited the coil? Since the magnet doesn't get "spent" by dropping it through a coil (you can drop it all day long and it'll still work). What you're capturing is the kinetic energy of the magnet, and not some intrinsic magnetic energy.

That being said, you can store energy in a magnetic field (which is basically what inductors do).
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Re: Extracting energy from a permanent magnet

Put a permanent magnet in a coil, heat it above the curie temperature, you get electricity in the coil when the field vanishes.

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Re: Extracting energy from a permanent magnet

Not sure if this is what the OP is really asking, but I read it as "How does a permanent magnet lose its energy?" I had the great idea of magnetically powered generators when I was younger, and while Ive grown to know it shouldnt be feasible, I just cant figure out how the magnets lose theyre energy.

Like, when I use a neodynium magnet to pick up a piece of steel, that takes energy from the magnet, but is the magnets field any weaker when the steel is removed? Does interacting with the steel disorganize a small amount of the magnets atoms?

Technical Ben
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Re: Extracting energy from a permanent magnet

Yes.
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Vaniver
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Re: Extracting energy from a permanent magnet

You, sir, name? wrote:If you were capturing energy from a magnet through that process, what energy does the magnet use to recover it's B-field once it's exited the coil? Since the magnet doesn't get "spent" by dropping it through a coil (you can drop it all day long and it'll still work). What you're capturing is the kinetic energy of the magnet, and not some intrinsic magnetic energy.
My impression is that the magnet does not fully recover its B field, and that if you were to do it all day long, for enough days, the magnet's net magnetic moment would decrease noticeably.
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ThomasS
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Re: Extracting energy from a permanent magnet

gmalivuk wrote:
zalzane wrote:A magnetic field does not store energy. All particles have a magnetic field, but their arrangement in compounds are usually too random and ecstatic to produce a measurable field.
Permanent magnets, however, have the poles of the particles all lined up, creating a measurable field.

Yes, and lining all the particles up like that requires an input of energy.

Lining up all the magnetic dipoles requires an input of energy? You sure about that? If I make a big stack of permanent magnets with the north poles up and the south poles down, I'm pretty sure I get energy out every time I add another magnet....

And isn't that how magnetic grains form? When hot enough, thermal energies randomize the little dipoles. Then if you you cool it slowly a few will be fixed in place first and their neighbors become oriented like them. The result is a number of grains form, each of which has (internally) a consistent alignment. Because of the randomness of the initial distribution, the result doesn't have a (net) permanent magnetic field. Then if you go to magnetize it by exposing it to a large field, the most correctly aligned grains tend to grow while the least correctly aligned grains tend to shrink. But then impurities and other imperfections get in the way of the boundary motion.

Or am I just misremembering some solid state physics? It has been years since I saw this stuff in class.

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Re: Extracting energy from a permanent magnet

ThomasS wrote:Lining up all the magnetic dipoles requires an input of energy? You sure about that? If I make a big stack of permanent magnets with the north poles up and the south poles down, I'm pretty sure I get energy out every time I add another magnet....

It is definitely the case that lining up the magnetic dipoles requires an input of energy. The way you describe it, you must put energy into that system to line up the north poles. Imagine you have two bar magnets, and you try to put them side by side such that both north poles face the same direction. The magnets want to repel in this configuration, so you will have to force them together. By forcing them together, you are doing work, and therefore putting energy into the system. Now say you let go. The magnets will want to swing around and line up north pole to south pole (anti-aligned). They will do this by quickly rotating and bashing together with a loud clang. Energy is released.

Two aligned magnetic dipoles have more energy then anti-aligned dipoles. A permanent magnet consists of many aligned dipoles, and demagnetizing it would entail causing these dipoles to become anti-aligned. The extra energy would have to be released somehow, and it could be used to do work or power a machine.

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Re: Extracting energy from a permanent magnet

JWalker wrote:
ThomasS wrote:Lining up all the magnetic dipoles requires an input of energy? You sure about that? If I make a big stack of permanent magnets with the north poles up and the south poles down, I'm pretty sure I get energy out every time I add another magnet....

It is definitely the case that lining up the magnetic dipoles requires an input of energy. The way you describe it, you must put energy into that system to line up the north poles. Imagine you have two bar magnets, and you try to put them side by side such that both north poles face the same direction. The magnets want to repel in this configuration, so you will have to force them together. By forcing them together, you are doing work, and therefore putting energy into the system. Now say you let go. The magnets will want to swing around and line up north pole to south pole (anti-aligned). They will do this by quickly rotating and bashing together with a loud clang. Energy is released.

Two aligned magnetic dipoles have more energy then anti-aligned dipoles. A permanent magnet consists of many aligned dipoles, and demagnetizing it would entail causing these dipoles to become anti-aligned. The extra energy would have to be released somehow, and it could be used to do work or power a machine.

So that leaves us with this question: Would extracting this energy net more work than what was required to put it in this state?

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Re: Extracting energy from a permanent magnet

It is definitely the case that lining up the magnetic dipoles requires an input of energy. The way you describe it, you must put energy into that system to line up the north poles. Imagine you have two bar magnets, and you try to put them side by side such that both north poles face the same direction. The magnets want to repel in this configuration, so you will have to force them together. By forcing them together, you are doing work, and therefore putting energy into the system. Now say you let go. The magnets will want to swing around and line up north pole to south pole (anti-aligned). They will do this by quickly rotating and bashing together with a loud clang. Energy is released.

But when you try to line them up end to end, you get the opposite result. Here is an experiment for you. Take two identical square magnets, with axis aligned magnetization. Place them end to end (north face touching south face) and measure the energy needed to separate them. Then, place them side to side with north faces and south faces opposite. Again measure the energy needed to separate them. Are you sure that the second case requires more energy?

I mean, maybe it does, but then why does a slowly cooled magnetic material spontaniously form grains with uniform magnetization? I'm not saying that I remember everything from my solid state physics course, but I do remember that this occurs, and it does not require an externally applied magnetic field.

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Re: Extracting energy from a permanent magnet

Kow wrote:So that leaves us with this question: Would extracting this energy net more work than what was required to put it in this state?
Not in a closed cycle, no. But, if we're given a permanent magnet, then the work has already been done, and the energy is captured in the structure of the magnet. By applying some energy to break that structure, and destroy the magnetic field, we can theoretically extract more energy than we used to break it, and that's all we're seeking.
ThomasS wrote:But when you try to line them up end to end, you get the opposite result.

Yes, but you don't increase the magnetic field that way. Actually, since you've moved the poles apart and effectively made the magnet longer, you've reduced the field density, and thus also reduced the total energy.
ThomasS wrote:I mean, maybe it does, but then why does a slowly cooled magnetic material spontaniously[sic] form grains with uniform magnetization? I'm not saying that I remember everything from my solid state physics course, but I do remember that this occurs, and it does not require an externally applied magnetic field.
I don't remember that--by my recollection, an external magnetic field is required. Actually, you have to go to some lengths to avoid external fields, since we live in one.
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Re: Extracting energy from a permanent magnet

EricH wrote:Yes, but you don't increase the magnetic field that way. Actually, since you've moved the poles apart and effectively made the magnet longer, you've reduced the field density, and thus also reduced the total energy.

Yes that you've reduced the total energy, versus two separate magnets. However, there is no theoretical difference between a 1x1x2 inch magnet with poles at the square ends and a two 1x1x1 inch magnets stuck together pole to pole. So the bigger magnet stores less energy? Oh boy, we'll just make the magnetic film as thin as possible to run our magnetic batteries!

Digging out my solid state physics texts is probably too much of a project for me to take on right now. But I will note that Wikipedia says that "Ferromagnetic materials can present spontaneous magnetization..." and has a separate article defining it as "the term used to describe the appearance of an ordered spin state (magnetization) at zero applied magnetic field...".

A few non-wiki pages which seem to agree:
http://www.irm.umn.edu/hg2m/hg2m_b/hg2m ... omagnetism

I actually have vague memories of rather non-trival arguments involving crystal structures and the like to understand why the dipoles in ferromagnetic materials are happiest when they are all aligned. Earth's magnetic field is negligible in comparison to the fields produced by neighboring molecules in the standard strongly ferromagnetic materials.

Basically, it seems to me that you are claiming that an external magnetic field is required during the phase transition to change from paramagnetism to ferromagnetism. However, every reference I've found so far is clear in the statement that the things are microscopically ordered below the curie temperature and disordered above it.

I'm not entirely sure the extent to which pure quantum effects help things along... but my real point is just that I don't think it is particularly obvious that there is energy stored within a permanent magnet.

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Re: Extracting energy from a permanent magnet

In nature both materials where all the tiny dipoles want to line up parellel (adding to eachother), and where they want to line up antiparellel (cancelling eachother) exist. Permanent magnets are made of the first kind, which is called ferromagnetism. So yeah, The magnitization of permanent magnets is spontanously formed when the material is cooled, and does not require any energy input. Quite the opposite, it costs energy to break that state. I'd have to check my solid state physics textbooks to look up the exact process of how they are made. But you don't need to put in magnetic energy or anything like that.

In fact, a very basic fact about magnetic fields is: They do no work!

Using a permanent magnet does not expend it. A magnet is not a battery. A magnet does no work, so it expends no energy. So it's not used up either. Permanent magnets will slowly lose their fields over time, but as far as I know that is a natural phenomenon that is a result of the 2nd law, and independent of usage. There are no doubt tricks you can use to speed this up, but normal usage is, afaik, not one of them.
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Re: Extracting energy from a permanent magnet

Wikipedia actually has a very good explanation:
Ferromagnetic materials can be magnetized in the following ways:

- Heating the object above its Curie temperature, allowing it to cool in a magnetic field and hammering it as it cools. This is the most effective method, and is similar to the industrial processes used to create permanent magnets.
- Placing the item in an external magnetic field will result in the item retaining some of the magnetism on removal. Vibration has been shown to increase the effect. Ferrous materials aligned with the Earth's magnetic field and which are subject to vibration (e.g. frame of a conveyor) have been shown to acquire significant residual magnetism. A magnetic field much stronger than the Earth's can be generated inside a solenoid by passing direct current through it.
- Stroking - An existing magnet is moved from one end of the item to the other repeatedly in the same direction.

Magnetized materials can be demagnetized in the following ways:

- Heating a magnet past its Curie temperature - the molecular motion destroys the alignment of the magnetic domains. This always removes all magnetization.
- Hammering or jarring - the mechanical disturbance tends to randomize the magnetic domains. Will leave some residual magnetization.
- Placing the magnet in an alternating magnetic field with an intensity above the materials coercivity and then either slowly drawing the magnet out or slowly decreasing the magnetic field to zero. This is the principle used in commercial demagnetizers to demagnetize tools and erase credit cards and hard disks, and degaussing coils used to demagnetize CRTs.
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JWalker
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Re: Extracting energy from a permanent magnet

Diadem wrote:In fact, a very basic fact about magnetic fields is: They do no work!

This, I'm embarrassed to say, I never understood. The reason why we say the magnetic field does no work is that its divergence is always zero. However, this is also the case for an electric field resulting from an equal amount of positive and negative charges (at all points aside from where the charge is). Nobody would say an electric dipole field does no work, yet the magnetic dipole field has the same form.

Picture two permanent magnets, placed far away from each other. If they are lined up correctly, they will experience an attractive force. This force will cause the magnets to accelerate towards each other. Clearly work is then being done on the permanent magnets, but if it doesn't come from the magnetic field, then where does it come from? I have not yet heard a satisfactory answer. I could also ask the same exact question except with electric dipoles, and no one would have any qualms about the electric field doing work, but an electric dipole field is mathematically identical to a magnetic dipole field.

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Re: Extracting energy from a permanent magnet

JWalker wrote:In fact, a very basic fact about magnetic fields is: They do no work!

They do no work on charges (where [imath]\vec{F}\perp\vec{v}[/imath]). They do perform work on magnetic moments, though.
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Re: Extracting energy from a permanent magnet

You, sir, name? wrote:
JWalker wrote:In fact, a very basic fact about magnetic fields is: They do no work!

They do no work on charges (where [imath]\vec{F}\perp\vec{v}[/imath]). They do perform work on magnetic moments, though.

Looks like you misquoted me there. Also, Griffith's in his E&M book flat out says mag. fields always do no work. Another subtlety, all magnetic moments are constructed from charged particles, if a magnetic field does work on a magnetic moment, it is doing work on a charge.

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Re: Extracting energy from a permanent magnet

JWalker wrote:
You, sir, name? wrote:
JWalker wrote:In fact, a very basic fact about magnetic fields is: They do no work!

They do no work on charges (where [imath]\vec{F}\perp\vec{v}[/imath]). They do perform work on magnetic moments, though.

Looks like you misquoted me there. Also, Griffith's in his E&M book flat out says mag. fields always do no work. Another subtlety, all magnetic moments are constructed from charged particles, if a magnetic field does work on a magnetic moment, it is doing work on a charge.

Okay, so the potential energy of a magnetic moment in an external B-field is
$U = -\vec{\mu}\cdot\vec{B}$
Therefore the force acting upon it is
$\vec{F} = \nabla U = -\nabla(\vec{\mu}\cdot\vec{B})$
Consider some place where magnetic moment is constant, [imath]\nabla\vec{\mu} = 0[/imath] (an ideal ferromagnet)
$\vec{F} = -(\nabla\vec{\mu})\cdot\vec{B} - \vec{\mu}\cdot\nabla\vec{B} = - \vec{\mu}\cdot\nabla\vec{B}$
So, for certain values of B and [imath]\mu[/imath] (again, \mu is constant)
$W = \int_L \vec{F}\cdot d\vec{l} = -\vec{\mu}\cdot\int_L \nabla\vec{B} = -\mu ( \vec{B}(l_0) - \vec{B}(l_1)) \ne 0$

Disclaimer: It's 6:45 AM and I'm about to go to sleep. May contain atrocities against physics.
Last edited by You, sir, name? on Sat Jun 27, 2009 3:01 pm UTC, edited 1 time in total.
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Re: Extracting energy from a permanent magnet

I''m confused as hell now. And I seem to have misplaced my Griffith's. Damn.
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Re: Extracting energy from a permanent magnet

Diadem wrote:I''m confused as hell now. And I seem to have misplaced my Griffith's. Damn.

I think it makes a little sense if you think of it in terms of magnetic and electric charges. Now that theory is physically wrong, but it is mathematically correct. Expressed in magnetic charge theory, you get a Lorentz force that looks like this:
$\vec{F} = q_e\left(\vec{E} + \frac{\vec{v}}{c} \times \vec{B}\right) + q_m\left(\vec{B} - \frac{\vec{v}}{c} \times \vec{E}\right)$
(Lifted from Wiki:Magnetic charge)

From this expression, it is very clear that magnetic fields do no work on electrical charges (which is indeed true), but they do work on magnetic charges (which can be used to build a model of magnetic moments), and vice versa. Electrical fields do no work on magnetic charges, but do work on electrical charges.

Though this explanation is pretty dubious at best.
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Re: Extracting energy from a permanent magnet

But that would mean that God, er, Griffith, is wrong.
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Re: Extracting energy from a permanent magnet

Diadem wrote:But that would mean that God, er, Griffith, is wrong.

Wrong is probably not he word. It's a simplified view of electrodynamics, so he is right in an unspecified subset of electrodynamics. It is an introductory textbook for undergrads, after all, so it's pretty justifiable compromise between being right and being understandable.
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Re: Extracting energy from a permanent magnet

And in Electromagnetism God is spelled Jackson anyways....
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rotarity
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Re: Extracting energy from a permanent magnet

Well, the point is that, as mentioned before, magnetic moments are not primitive entities, they are made up of charges. Whenever it appears as if the magnetic field is doing work on a magnetic moment, at the level of charges the work is actually being done by a hidden electric field.

For example, consider a current-carrying wire loop being rotated through a magnetic field. The magnetic force acting on a charge in the wire will have a component perpendicular to the direction of the wire. Since the charge continues moving along the wire, there must be another force which counteracts this perpendicular component. This force actually comes from the electric field induced by the Hall effect, and it is this electric field which actually does the work.

EDIT: I just remembered the rule about no external links for small post count. Well, you can look up the Hall effect on Wikipedia without the link, I guess.

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Re: Extracting energy from a permanent magnet

That isn't quite true, though, as B-fields can act on particle spin (which is decidedly can not be reduced to a moving charge.) Magnetic moments as current loops is a classical model that does not tell the whole story.
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Re: Extracting energy from a permanent magnet

For that matter, isolated magnetic charges (monopoles) are a feature of many GUTs, and may turn out to be part of the next iteration of theory unification.

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Re: Extracting energy from a permanent magnet

rotarity wrote:Well, the point is that, as mentioned before, magnetic moments are not primitive entities, they are made up of charges. Whenever it appears as if the magnetic field is doing work on a magnetic moment, at the level of charges the work is actually being done by a hidden electric field.

If you're clever enough, you can explain any event where the electric field does work as being done by hidden magnetic fields... E and B fields mix and match in the right frames of reference.
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rotarity
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Joined: Thu Feb 05, 2009 11:58 pm UTC

Re: Extracting energy from a permanent magnet

Jakell wrote:
rotarity wrote:Well, the point is that, as mentioned before, magnetic moments are not primitive entities, they are made up of charges. Whenever it appears as if the magnetic field is doing work on a magnetic moment, at the level of charges the work is actually being done by a hidden electric field.

If you're clever enough, you can explain any event where the electric field does work as being done by hidden magnetic fields... E and B fields mix and match in the right frames of reference.

Work is not frame-independent though, so you can't account for it by switching reference frames. If you switch to the rest frame of the charges you can even make the work disappear entirely. I agree that dividing the Lorentz force into electric and magnetic components and saying that the magnetic component does no work is a bit of an artificial distinction.

darryl barton
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Re: Extracting energy from a permanent magnet

I am not a scientist but I have made a number of physical and thought experiments involving permanent magnets.

I think of a permanent magnet‘s magnetic field as an active force as opposed to a stable, inactive force (like a chemical adhesive that can suspend a [1 pound] object for 1 second i.e.1hp=550w simply through the bonding of surfaces).

Being an active force it stands to reason that there must be a “expenditure” of energy. That said, there must be the presence of an energy reserve to be expended.

My theory is that the common permanent magnets, manufactured and naturally forming have VAST reservoirs of atomic energy lock inside of them, much like fissionable metals but instead of heat, light and partial radiation the permanent magnet‘s reservoir of energy consists of what I call “mazma“.

I also believe that “mazma“ can be accessed / released over a very short period of time, years, month, days, minutes and even seconds as opposed to centuries.

The following are a few numbers that will demonstrate the crazy amount of potential.

A small, 10lb, neodymium, permanent magnets about the size of a lozenge would exert the equivalent force of 1 horse power (1hp) every 55 seconds (10 pounds x 55 seconds = 550 pounds @ 1 second).

In a 24 hour period said magnet would exert the equivalent force of 26.1818 horse power.
(24 hours x 60 seconds = 1440 seconds / 55 seconds = 26.1818hp)

Over a period of a year, said magnet would exert the equivalent force of 9556.357 horse power. (365 days x 26.1818hp= 9,556.357 hp)

Over a period of a 200 years (theoretical life span of said magnet), said magnet would exert the equivalent force 1,911,271.4 horse power. (200 years x 9,556.357 hp = 1,911,271.4hp). Almost TWO MILLON HORSE POWER form a small, 10lb, neodymium, permanent magnets about the size of a lozenge.

1 horsepower hour = 6.4161555927e-7 kiloton [explosive]

1,440 seconds or 1 horsepower hour = 6.4161555927e-7 kiloton of [explosive] energy 1,911,271.4hp / 1440 sec = 1,327.27 horsepower hours x 6.4161555927 kilotons of [explosive] energy = 8,515.98 kilotons of [explosive] energy. I think…

1,911,271.4hp x 745.7watts (1 US hp) = 1,425,235,082.98 watts

Q: How far could the average person drive their vehicle on 8,515.98 kilotons of [explosive] energy or almost 1.5 billion watts of electricity?

Carnildo
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Re: Extracting energy from a permanent magnet

darryl barton wrote:I am not a scientist but I have made a number of physical and thought experiments involving permanent magnets.

I think of a permanent magnet‘s magnetic field as an active force as opposed to a stable, inactive force

This is where you go wrong. A magnetic field, like a gravitational field, is, in your terms, an "inactive force". Since the rest of your theory is built off of an incorrect assumption, it's meaningless.

stianhat
Posts: 175
Joined: Mon Jun 13, 2011 6:31 pm UTC

Re: Extracting energy from a permanent magnet

Tass wrote:Put a permanent magnet in a coil, heat it above the curie temperature, you get electricity in the coil when the field vanishes.

Correct, however that energy did not come from the magnet, it came from you when you put it in the coil.

ThomaSs wrote:I mean, maybe it does, but then why does a slowly cooled magnetic material spontaniously form grains with uniform magnetization? I'm not saying that I remember everything from my solid state physics course, but I do remember that this occurs, and it does not require an externally applied magnetic field.

Well, if it happens in a totally field-free environment, the orientation of the different magnetic domains as a whole will be random (within the same domain, they will still be parallel). If you do this in a magnetic field you will grow the domains that are aligned to the external field and shrink the ones that are perpendicular. Different materials will have a different hysteresis loop (the curve describing the correlation between external and internal field strength for magnetization and demagnetization. They are usually different. A magnet can be "hard" - square or "soft" - linear-ish)
Last edited by stianhat on Wed Jul 17, 2013 2:32 pm UTC, edited 1 time in total.