Why are magnets debunked when talked as a source of energy?

I think saying a magnet cannot provide energy would be no different than saying gravity does not either. There is still a core of molten lava inside of the Earth that wouldn't have ever been there without the force of gravity. I don't think that just because you couldn't use that energy in order to reuse it an infinite number of times, doesn't mean that it is not there.

 

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You are all confused because you don't understand the absolute frame.

 

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i might regret it too but i will take a stab at it.
i AM confused about this "superconducting toroidal solenoid"
i will assume its an electrically lossless coil of wire wrapped around a toroidal core of ferro-material.
are you sure you aren't missing "inductive kick back"?
anytime you energize a coil of wire it set up an expanding magnetic field.
this expanding field generates its own voltage in the coil, discreet from the energizing voltage.
at resonance this can give the appearance of getting more out than you put in.

also, i am not aware of ANY real world lossless wire.

edit:
after thinking some more i believe what you are describing cannot exist.
the scenario you describe will have an infinite Q, there will be no resistance to impede current.
the sides of the bandwidth curve will almost, if not actually, be vertical.
at resonance this apparatus will destroy itself due to lack of circuit resistance, the cause being excessive current.

 

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Good show for trying to be constructive at least - a rarity so far here. What follows in answer is brief as cannot stay long.

Correct to this point.

As per my #19 Faraday's law is fully respected at all times and situations. Hence inductive kick-back - meaning here self-inductance in toroid windings - is accounted for as it must be. It's failure of Lenz's law as applying to magnetized media, especially in above-saturation-regime I draw attention to as key consideration. The media does *not* 'kick-back' inductively to any appreciable degree in the considered well above saturation regime. Need I repeat - that is a key factor.

I chose superconducting solenoid for the reason of avoiding any useless distraction and confusion over having to account for normal resistive losses in the total energy balance. The principle I push is not at all dependent on superconductivity per se, just simpler to analyze when dissipative 'copper losses' is absent.

But, despite my efforts last posting to set the scene clearly, you assume it somehow all operates in AC mode and somehow relies on resonance. None of that is the case! I consider the energetics involved when an arbitrarily small change in the solenoid applied supercurrent is made, and that could be over an arbitrarily small or large time scale. We are looking at a one-off pulse situation - in order to establish the physical principles at work. All that counts is that the solenoidal circuit electrically 'sees' an effectively zero susceptance air-core - owing to media total saturation. But there nevertheless is an extra 'hidden' interaction energy produced owing to the saturated media actually being there. Please go back and study that post again - all of it. Must go.
[Edit: You may have gotten the AC idea from the last part in #19 where there is discussion of cycling of sorts. But that could involve discreet step pulses or whatever, and at any rate just concentrate on the material preceding that last stuff.]

 

How is that different from a magnetic amplifier using a saturable reactor? Those have been in use since the 1940's.

 

Oh this is a rush - just caught your entry. In your case, I suggest do concentrate on the last part in #19 - saturable reactors do not bother about the relativistic mass/inertia changes owing to an electrically hidden internal excess energy of quantum mechanical interaction nature! Check out carefully the thinking in my section on the shrinking sized superconducting loop current - effect of fluxoid quantization in the limit of small loop size. Lenz's law fails!

 

mag-amps have a small slit in the core to prevent over saturation and may not apply in this case.

 

well see, that's the thing, changing current.
ANYTIME you alter the strenght of the current you are also introducing the "inductive effect".
the ONLY way to prevent this is to hold the coil current steady.

this "hidden" energy could very well be caused by the "arbitrarily small" current variations you mentioned.

edit:
even though you say you aren't talking about AC you are in fact doing so.
from the magnetic fields point of view a varying DC current is the same as an AC current.
it's the change in current that affects the feild, not its direction.
well, the direction would reverse the field but the effect would be the same.

 

Magnetic amplifiers rely on saturation to work. If they don't saturate they don't work.

You are probably thinking of regular inductors. In most inductors saturation is bad, and thus air gaps (slits or distributed) can help reduce the odds of hard/sudden saturation and the resulting uncontrolled increase in current.

 

i no longer have my textbooks on this subject and mag-amps were well on there way out when i DID have them.
transformers don't have slits but i'm pretty sure that mag-amps do.

no, i'm not.

this in itself says magamps must have slits.
they control a large output by varying a small input current.
this wouldn't be possible with a saturated core.

 

None of the ones I built did.

No, that's what I am saying. The uncontrolled increase in current is what you WANT in a magnetic amplifier. You saturate the core with a small control voltage, and a larger current is then conducted when the core saturates. If the core didn't saturate hard then a magnetic amplifier wouldn't work. Indeed, you want to use hard-saturating materials, rather than materials like powdered iron that have softer B-H curves.

Again, that's how it works. You saturate the core with the small input current and you get a large output when the incremental inductance drops to near zero.

 

Is the potential energy for this setup infinite? Meaning for as long as the magnet lasts? Is this not fighting gravity at all times? I mean, I can feel the tension in the strings preventing the nails from reaching the magnet. I don't understand how is the magnet not doing work in this case. I did give energy to the system by getting the nails close to the magnet, but if I don't disturb the setup, I suppose it will last for the life of the magnet, right? Isn't that more energy than I originally spent?

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well then, what the frak was i thinking about?
no, it's not a typical clock motor that uses a slit and a shorted loop of copper.
maybe i'm confusing theory with application, a slitted core will indeed prevent saturation.
anyway . . .

 

?? No. If you cut the string the potential energy is converted into a finite amount of kinetic energy.

Because there is force but no motion.

Imagine you put a weight on a floor. There is force (the weight pushes on the floor) but no motion - so no work.

 

You don't understand the definitions of the words you are using. "work" and potential energy are both force times distance. What does time have to do with that? (answer: nothing). There is no more work being consumed here than by a book sitting motionless on a table. Only if the object is in motion is there work being done.

 

You aren't understanding the issue here. The issue is whether magnet can be used as a continuous source of energy without any input power from another source. Ie, can it be used as a perpetual motion machine. That's what this is about.

 

The magnetic force on the nails is not moving them through a distance, hence no work is done.


I know what you're thinking: "If I hold up a heavy shopping bag, I'm not doing any work, yet why do I become tired and fatigued?"

 

In classical mechanics we can easily construct a perpetual motion machine by setting two identical magnets in orbit about their barycenter.

Of course in reality energy will be radiated out of the system.

 

post #17 I thought I understood your POV. So when we force the domains to align we give the permanent magnet potential energy. Like the spring example the more kinetic energy we apply to compressing the spring the greater potential energy the spring contains to convert back to kinetic E.
’’’’’’’’’’’’then I started typing the below and I saw exactly where my mistake was to your POV. You saying the magnet /spring is only a device to convert potential E into kinetic E and does not supply any E. This is what I was typing.’’’’’’’’’’’’’’’
To keep your POV consistent would the domains start moving out of alignment when the permanent magnetic field is used? Or else the magnet would act as a continuous source of potential E.
’’’’’’’’’’’’’My bad to your POV ended and I was chuffed I got it’’’’’’’’’’’’’’

Then I thought about an electromagnet if we lift something with it the current has to keep flowing to hold on to object we lifted against gravity which requires a constant flow of electrons, can that flow be viewed as energy input required to hold the object up against gravities constantly applied kinetic E? And now again Im at how does the permanent magnet hold on to the object against gravity if it doesn’t use energy? Like the brick on the table and sleeping on the bed example, we don’t need to fight gravity anymore, but the bed and tables bonded atoms take the stress/work to hold us and the brick up against gravities constantly applied kinetic E and thats also the reason for gravities compression on matter a constant force applied even if the matter is stationary. It seems the magnet has to supply at least 9.8m/s of acceleration to the object to keep it up to overcome gravity. Where am I going wrong now?

 

Not in an ideal system. In an ideal (superconducting) magnet no additional energy is required to hold the object. In a real system, of course, some of that energy is converted to heat via resistance so you have to add more energy to keep the magnet operating.

The same way a stick could hold the object aloft against gravity without using energy.

Same situation with something floating on a lake. There are no "bonded atoms" holding anything up and yet gravity is successfully "beaten."

Again, it takes zero work to hold something in place against gravity.