bouncing on a magnetic spring/cushion

[lemur]

Imagine you have two magnets set up so they repel each other and cannot turn. Now you bounced up and down on one of the magnets repeatedly but not hard enough for the magnets to touch. You are imparting energy into this 'spring-cusion' but where does the energy go? Does some of it become electric current and/or EM waves? If EM waves are produced, is their wavelength determined by the rate of the bouncing and the speed of light? Can you modulate the wavelength of very low frequency radio waves by bouncing magnets off of each other and changing the rate of the bouncing?

Edited January 18, 2011 by lemur

[Xittenn]

In any [math] F_{un} [/math] between two magnets, usually as a consequence of momentum, the energy that isn't returned to the object as a momentum in the opposing direction would be dissipated internally as heat due to breaks in ferromagnetic structure .... Current shouldn't flow but if there were an inductive coil or a conductor in between me thinks it might still not flow ... because of the equal and opposing fields. :|

 

I would assume that it could be demonstrated that the same heating and cooling effect, a consequence of the Gibbs Free Energy, seen in elastics would be seen in magnets as they approach and are repelled. I can't however find any supporting links and none of my texts discuss this as a possibility! I need an E&M text ...

Edited January 18, 2011 by Xittenn

[lemur]

In any [math] F_{un} [/math] between two magnets, usually as a consequence of momentum, the energy that isn't returned to the object as a momentum in the opposing direction would be dissipated internally as heat due to breaks in ferromagnetic structure .... Current shouldn't flow but if there were an inductive coil or a conductor in between me thinks it might still not flow ... because of the equal and opposing fields. :|

So the magnetic fields conserve force perfectly? All the energy you put into compressing and releasing the fields gets transferred back to the molecules of the magnets themselves? That seems strange to me since I would think that there would be some interaction effect of the fields manipulating each other.

 

I would assume that it could be demonstrated that the same heating and cooling effect, a consequence of the Gibbs Free Energy, seen in elastics would be seen in magnets as they approach and are repelled. I can't however find any supporting links and none of my texts discuss this as a possibility! I need an E&M text ...

I googled Gibbs free energy but I can't get a concrete image of how it works. All I can think is that force gets translated into tensile tension in moving objects, which results in either momentum-transfer or friction/heat, variously. Since there can't be any friction between the repelling magnetic fields, I assume your comment about breaks in ferromagnetic structure would apply (I assume this refers to friction between the (blocks of) atoms. I thought maybe some of the energy would actually be absorbed by the magnetic fields themselves and thus have to be dissipated as electric current or EM waves/photons. I don't understand why particles of matter always seem to be radiating some level/frequency of radiation but magnetic fields wouldn't. Maybe the magnetic fields are too big and strong relative to the more independent atomic/molecular electrons of black bodies?

 

 

[swansont]

As Xittenn has mentioned, there is heating, and if the magnets are conductors there will be eddy currents induced in them, which would induce heating as well. Ultimately you will get radiation, because there is blackbody radiation; you would also get radiation from the acceleration of the charges.

[lemur]

As Xittenn has mentioned, there is heating, and if the magnets are conductors there will be eddy currents induced in them, which would induce heating as well. Ultimately you will get radiation, because there is blackbody radiation; you would also get radiation from the acceleration of the charges.

I had to google what eddy currents are. These must only occur as electric currents in a conductor, though, so how would they form by magnets interacting in air? Would they expel current via moisture in the air? As for the blackbody radiation, are you saying that the magnetic fields themselves radiate as a result of energy put into them by bouncing? Or do you just mean the magnets themselves are made of iron that emits blackbody radiation according to temperature? What I am really interested in knowing is whether the bouncing of the magnets against each other itself generates EM waves and whether the (very long) wavelength of the waves would be modulated by the speed of the bouncing (sorry for using the word "bounce" so much. It sounds silly to me but I can't think of a more scientific sounding word for alternately compressing and releasing two opposed magnets as the repel one another).

[Xittenn]

I had to google what eddy currents are. These must only occur as electric currents in a conductor, though, so how would they form by magnets interacting in air? Would they expel current via moisture in the air? As for the blackbody radiation, are you saying that the magnetic fields themselves radiate as a result of energy put into them by bouncing? Or do you just mean the magnets themselves are made of iron that emits blackbody radiation according to temperature? What I am really interested in knowing is whether the bouncing of the magnets against each other itself generates EM waves and whether the (very long) wavelength of the waves would be modulated by the speed of the bouncing (sorry for using the word "bounce" so much. It sounds silly to me but I can't think of a more scientific sounding word for alternately compressing and releasing two opposed magnets as the repel one another).

 

If a spring is compressed and then allowed to return the energy to the source and the spring has no internal friction .... will it make a sound? Not if it is in a vacuum ..... ??? ?.?

[swansont]

I had to google what eddy currents are. These must only occur as electric currents in a conductor, though, so how would they form by magnets interacting in air? Would they expel current via moisture in the air?

 

You have two magnets in your setup. They interact with each other, and some magnets are made of conductors.

 

As for the blackbody radiation, are you saying that the magnetic fields themselves radiate as a result of energy put into them by bouncing? Or do you just mean the magnets themselves are made of iron that emits blackbody radiation according to temperature? What I am really interested in knowing is whether the bouncing of the magnets against each other itself generates EM waves and whether the (very long) wavelength of the waves would be modulated by the speed of the bouncing (sorry for using the word "bounce" so much. It sounds silly to me but I can't think of a more scientific sounding word for alternately compressing and releasing two opposed magnets as the repel one another).

 

Any object with a temperature radiates.

 

The magnets will form other photons if you are accelerating the charges within them; that's one way that you get photons, and the only one that would be happening here.

[John Cuthber]

I conduct electricity.

Magnetic forces have infinite range .

The moving magnets will induce a current in me.

This will transfer energy to me and warm me up.

 

Other things may also absorb power from your system, but my existence is sufficient to show that, in the end, the energy will dissipate.

[SMF]

This is very interesting. If I correctly interpret what Swansont is saying, the bouncing magnet would continue to bounce for a while without any more energy input, but the bounce would eventually damp out. I wonder how long this would take if done in a vacuum. I also presume that this would be the only "friction" loss in rare earth maglev bearings being contemplated for very low wind, vertical shaft, wind generators and other devices. SM

[lemur]

If a spring is compressed and then allowed to return the energy to the source and the spring has no internal friction .... will it make a sound? Not if it is in a vacuum ..... ??? ?.?

Is your point that the magnetic fields form a perfect spring with no internal friction, which return exactly the same amount of energy as is put in? A spring in a vacuum wouldn't make a sound but EM fields seem to behave as if they are surrounded by a medium, insofar as nothing can insulate EM emissions. Another way to frame my question/issue is that when electrons are compressed against each other at the molecular level, they transfer energy, which sometimes causes them to change levels and emit photons. So what would prevent two magnetic fields from interacting in the same manner as electrons at the (sub)atomic level?

 

 

You have two magnets in your setup. They interact with each other, and some magnets are made of conductors.

So the eddy currents occur in the solid metal of the magnets? Here's what I don't get. If electricity conducts through the electrons within the conductive material, why wouldn't it conduct through the magnetic field? Isn't the magnetic field just an aggregate field consisting of multiple microscopic electrostatic fields? So it seems like if you could observe the atoms of a conductor transmitting electricity at the atomic level, you would see many electric fields repelling each other in moving waves, no?

 

The magnets will form other photons if you are accelerating the charges within them; that's one way that you get photons, and the only one that would be happening here.

By "accelerating" the charges, which charges are you referring to? Not the (macro) magnetic fields themselves? You mean accelerating the charges at the microscopic level of the atoms? BTW, are the macro magnetic fields different force than the electrostatic force at the micro-atomic level? If so, how do they get so far from their nuclei?

 

I conduct electricity.

Magnetic forces have infinite range .

The moving magnets will induce a current in me.

This will transfer energy to me and warm me up.

 

Other things may also absorb power from your system, but my existence is sufficient to show that, in the end, the energy will dissipate.

 

Ok, so your body or other resisters the electric current finds its way into will dissipate the current as heat. But does the compression of the magnetic fields also dissipate any energy? Or does it perfectly conserve it until it is transferred to particles it pushes against?

 

This is very interesting. If I correctly interpret what Swansont is saying, the bouncing magnet would continue to bounce for a while without any more energy input, but the bounce would eventually damp out. I wonder how long this would take if done in a vacuum. I also presume that this would be the only "friction" loss in rare earth maglev bearings being contemplated for very low wind, vertical shaft, wind generators and other devices. SM

If nothing else, the accelerating and decelerating motion of the magnets would result in "recoil" that would eventually dissipate the motion of the spring, I think.

 

Thanks all for fielding this question/issue so well. I'm still not conclusively convinced of whether some of the energy gets emitted directly from the magnetic fields or whether they are a perfect frictionless spring with no emissions from the fields directly. If anyone wants to generate a conclusive yes/no and why/how, that would be interesting. Otherwise, thanks for contributing to my ever perplexing partial understanding of magnets.

 

 

[Xittenn]

 

Is your point that the magnetic fields form a perfect spring with no internal friction, which return exactly the same amount of energy as is put in? A spring in a vacuum wouldn't make a sound but EM fields seem to behave as if they are surrounded by a medium, insofar as nothing can insulate EM emissions. Another way to frame my question/issue is that when electrons are compressed against each other at the molecular level, they transfer energy, which sometimes causes them to change levels and emit photons. So what would prevent two magnetic fields from interacting in the same manner as electrons at the (sub)atomic level?

 

 

My point is simply that there are many ways in which energy can be 'dissipated' out of the system. Normally speaking no system is ideal so there will be certain losses due to internal resistance.

 

Now your question was will there be EM radiation emitted as a cause of two masses with ferromagnetic properties interacting in opposition in relation to their magnetic dipole moments. My suggestion is to first ask yourself what creates EM radiation and then quantize this into your system or model. These are rather vague questions as there are many factors needing to be accounted for.

 

The simple answer is sure there will be EM radiation. But this will not be as an effect of simply pressuring two opposing charges together. As far as I understand if you shoot two electrons at each other in a vacuum there isn't a resulting photon emission due to their interaction only due to their acceleration. I think in this case of two electrons the photons would be emitted into the paired electron and subsequently a reversal of direction ....

 

My understanding here is limited, though it is an area of interest that I still wish to further understand :/

Edited January 18, 2011 by Xittenn

[lemur]

My suggestion is to first ask yourself what creates EM radiation and then quantize this into your system or model. These are rather vague questions as there are many factors needing to be accounted for.

Right, and I'm trying to account for the factors. EM radiation is created when electrons first absorb energy and jump to a higher energy state, then dropping back down to a lower state. What confuses me with the magnetic fields is that these large fields seem to be extensions of the electrostatic fields that compose the electrons themselves, so it's as if the fields extending out of the magnets are themselves macro-electrons created from the amalgamation of numerous atomic electrons in the same orientation. So would these magnetic fields only generate photons if they would somehow become excited and change levels? I assume this wouldn't be possible since magnets lose their magnetism when they heat up. What perplexes me is what the relationship between the magnetic field of the magnets and the atomic electrons that compose them is. Is the large magnetic field an array of dipolar "threads" extending from a single atom on one pole and seeking the shortest possible route to a single atom on the other pole, which a chain of single-aligned atoms in between? Or do the "threads" simply combine with each other to form a unified field? Further, are there literally electrons extending out of the negative pole and bending around to the positive pole? If the atomic level electrons merge into a single unified field, does this field maybe have more resistance to changing levels than independent electrons at the atomic scale? Too many questions, I know, but hopefully you can see how I'm thinking and identify any blatantly false assumptions.

 

The simple answer is sure there will be EM radiation. But this will not be as an effect of simply pressuring two opposing charges together. As far as I understand if you shoot two electrons at each other in a vacuum there isn't a resulting photon emission due to their interaction only due to their acceleration.

So does this imply that the two magnetic fields wouldn't generate EM radiation merely as a result of interacting/colliding but only due to their motion? The fact that they resist each other's motion is meaningless but the fact that they are accelerating is? If F=MA, shouldn't the force they exert on each other constitute acceleration in the same sense that a grounded object accelerates into the ground by gravity? But how would you define the mass of a magnetic field? Would it simply be the mass of the electrons that constitute it?

 

 

[swansont]

So the eddy currents occur in the solid metal of the magnets? Here's what I don't get. If electricity conducts through the electrons within the conductive material, why wouldn't it conduct through the magnetic field? Isn't the magnetic field just an aggregate field consisting of multiple microscopic electrostatic fields? So it seems like if you could observe the atoms of a conductor transmitting electricity at the atomic level, you would see many electric fields repelling each other in moving waves, no?

 

You can't conduct electricity through a magnetic field, it's the motion of charges, usually electrons. Electric or magnetic fields aren't physical objects. Electric fields do not repel each other.

 

 

By "accelerating" the charges, which charges are you referring to? Not the (macro) magnetic fields themselves? You mean accelerating the charges at the microscopic level of the atoms? BTW, are the macro magnetic fields different force than the electrostatic force at the micro-atomic level? If so, how do they get so far from their nuclei?

 

In the material. At the atomic level, by definition. What do you mean by "they" in asking how they get far from the nucleus? Fields can extend to infinity.

 

Ok, so your body or other resisters the electric current finds its way into will dissipate the current as heat. But does the compression of the magnetic fields also dissipate any energy? Or does it perfectly conserve it until it is transferred to particles it pushes against?

 

It's the transfer. Current flow requires work to be done. Moving atoms requires work, too.

[lemur]

You can't conduct electricity through a magnetic field, it's the motion of charges, usually electrons. Electric or magnetic fields aren't physical objects. Electric fields do not repel each other.

Ok, back to basics then. What is the relationship between an electron and its electric and/or magnetic fields? My impression was that electrons have electrostatic charge, which repels other electrons (negative charge) and attracts protons (positive charge). Electric current, I thought, was when energy is transferred through electrons as a kinetic medium, the way air pressure travels through the atmosphere as wind. Magnetic fields, I thought, appear at a right-angle from electric fields when they are moving as current. I'm not sure how static magnetic fields emerge without the motion of current, but I know they generate a corresponding electric field when they move, which is why magnets can be used to produce electricity.

 

Where I get confused is what the difference is between an electron itself and the fields it generates. If you call it a point-particle and distinguish it from the fields, what empirical basis do you have for the point-particle other than it being the center of the manifest fields? It makes more sense to me to say that the force-fields ARE the electron, but then I get confused about whether electric and magnetic fields are separate or parts of the same entity. Likewise, what is happening with the multitude of electrons and their field-force when they 'align' in the case of a magnet? Are the atomic-level force-fields combining to form a single macro field or are they all separate and interacting as separate entities? I don't know if it helps or not, but I look to the emergence of a gravity field from a multitude of atoms/molecules as similarly merging into a single macro-field, but is there some reason the fields of individual fields would interact differently in the case of gravitation as electrostatics?

 

In the material. At the atomic level, by definition. What do you mean by "they" in asking how they get far from the nucleus? Fields can extend to infinity.

Then why do atoms tend to remain microscopic? Is there any difference between the electrostatic repulsion of a magnetic field and the electrostatic repulsion of non-magnetized matter?

 

It's the transfer. Current flow requires work to be done. Moving atoms requires work, too.

Right, but does any of the work done in moving the magnetic fields not get conserved and returned to the magnets as they are compressed and released (bounced) against each other? Or do they contain/conserve the energy perfectly and return it in the same amount as it is imparted?

 

 

[swansont]

Current is the net movement of charge. It's not the energy — that's the potential difference (aka Voltage), which is the energy per unit charge.

 

Fields add together.

 

Right, but does any of the work done in moving the magnetic fields not get conserved and returned to the magnets as they are compressed and released (bounced) against each other? Or do they contain/conserve the energy perfectly and return it in the same amount as it is imparted?

 

There is no conservation of field, there is conservation of energy. I don't see the utility of talking of "moving fields around" since that doesn't tell you anything. When you push on one of the magnet there is a resistive force; you store energy in the system. If you release the magnet, it will oscillate, changing potential energy for kinetic energy. Some is lost to heat because you do work on the magnet, possibly causing some mechanical motion and because you will induce eddy currents. That energy will show up as an increase in temperature.

[lemur]

Current is the net movement of charge. It's not the energy — that's the potential difference (aka Voltage), which is the energy per unit charge.

 

Fields add together.

You seem to be giving information that is related to my questions, but I can't exactly directly apply it to answering the questions. I'm not sure it's worth your trouble to sort it out with me.

 

There is no conservation of field, there is conservation of energy.

What do you mean, in general? I am talking about conservation of energy within the two magnetic fields that extend beyond the magnets. Does all the energy imparted into those invisible force-fields end up back at the magnets or does some of it get emitted directly between the invisible fields and other electrons outside the magnets?

 

Some is lost to heat because you do work on the magnet, possibly causing some mechanical motion and because you will induce eddy currents. That energy will show up as an increase in temperature.

So the heat is due to friction among the atoms within the magnets, and that friction is caused by all force of pushing the two fields together being returned to the atoms in which the field is anchored? The eddy currents are electric currents that run through the magnets themselves?

 

When you say there is no conservation of field, do you mean that no electrostatic force within the material of the magnet itself has to be diverted into the force fields extending beyond the magnets? I.e. the forces of binding and configuration among the electrons of the iron atoms remain constant and new force emerges in the formation of the magnetic fields extending beyond the magnets?

 

 

 

[swansont]

Sorry, the "fields aren't conserved" was because I misread your post.

 

You push on objects. When you push on one magnet, it pushes on the other (and the other on it) because the magnetic forces are field forces. Fields don't push on each other. If you push on a magnet, whether by your hand or by another magnet, you can do some work of deformation, some of which ends up as thermal energy.

[Xittenn]

I'm not sure how you are mentally analyzing this interaction of fields. Fields are the effect of electromagnetic radiation and this is best described as the exchange of photons. The reason we do not see an object extend indefinitely is wavelength. Photon - Photon interactions are beyond the scope of this question ???

 

[edit]

 

That sounds really weird!

 

[edit]

 

[math] where \; does \; the \; energy \; go? \; \neq \; Photon \; - \; Photon \; interaction [/math]

 

and yet another point ....

 

If there is an induced current the energy to make this happen isn't coming from the magnets or their fields it is coming from the source pushing them together and is in addition to the energy required to push them together!