Free energy machine - find the flaw?

[AmandaM]

An old science teacher of mine recently quoted a debate on FB about free energy. He challenged some of his FB subscribers to discover what he calls the significant flaw in the reasoning behind this model for a "free energy" machine.

Aside from the laws of thermodynamics, is there a single significant flaw in the idea? He won't comment on it until somebody gets the answer, and just saying it's against the law isn't enough, apparently. I thought maybe it was because when you "hooked up" the machine to a wheel (or whatever you'd use to actually use it as a power generator) you'd have to have extra energy to overcome the resistance of it being hooked up to something else, does that make any sense? Or is that my scientific ignorance showing?

Here's the "design," so-to-speak:
I was playing with an old dynamo, and thought: what if the crank (the shaft and coil in the middle), spun frictionless, by magnetic force? Suspend the axle on either end with a ring of magnets (so it "floats"), plus, align other superconductor pieces (on the "axle/coil) with the stationary magnets around the outside, so that when one passes, it gets a minute "push" from the magnet. Not enough to really do much on its own, but rotating, each one getting a little "push." Then put the WHOLE assembly in a glass vacuum to remove any atmospheric friction. Wires can be set in liquid glass beforehand to attach to the ring inside to get the current out of the "closed" system.

[ellindsey]

You can't design an arrangement of magnets that imparts a constant torque to the rotor with no energy input. A stationary magnet that pushes against a magnet on the rotor so as to speed up the rotor as it goes by will also push against the magnet so as to slow down the rotor as it approaches. Magnetic fields are conservative - the total energy change from a closed path through a magnetic field will be zero, so you can't make the rotor spin faster with purely permanent magnets.

[Daald]

An old science teacher of mine recently quoted a debate on FB about free energy. He challenged some of his FB subscribers to discover what he calls the significant flaw in the reasoning behind this model for a "free energy" machine.

Aside from the laws of thermodynamics, is there a single significant flaw in the idea? He won't comment on it until somebody gets the answer, and just saying it's against the law isn't enough, apparently. I thought maybe it was because when you "hooked up" the machine to a wheel (or whatever you'd use to actually use it as a power generator) you'd have to have extra energy to overcome the resistance of it being hooked up to something else, does that make any sense? Or is that my scientific ignorance showing?

Here's the "design," so-to-speak:
I was playing with an old dynamo, and thought: what if the crank (the shaft and coil in the middle), spun frictionless, by magnetic force? Suspend the axle on either end with a ring of magnets (so it "floats"), plus, align other superconductor pieces (on the "axle/coil) with the stationary magnets around the outside, so that when one passes, it gets a minute "push" from the magnet. Not enough to really do much on its own, but rotating, each one getting a little "push." Then put the WHOLE assembly in a glass vacuum to remove any atmospheric friction. Wires can be set in liquid glass beforehand to attach to the ring inside to get the current out of the "closed" system.


I would point out that there is nothing that can be " spun frictionless".

[DrDave]

I can see 2 flaws

1. The "external" equipment to keep it running (generating the superconducting magnetic fields, and generating the vacuum) will need more energy than this thing would generate.

2. Consider 2 snapshots of the system. One when it is lined up with 1 magnet in the ring, one when it is lined up with the next magnet. These are at the same energy level, so there's no reason why the system would move from one snapshot to the next

[Dave Rogers]

Suspend the axle on either end with a ring of magnets (so it "floats"), plus, align other superconductor pieces (on the "axle/coil) with the stationary magnets around the outside, so that when one passes, it gets a minute "push" from the magnet.

As it comes towards the magnet, it gets an equal "push" in the opposite direction. The time-average of the two pushes is zero. When you hook up a load to the dynamo, the current flowing in the wires of the dynamo exerts a magnietic force that opposes the direction of rotation, so the coil slows down and stops; there's no net effect from the magnets on the outside to keep it going. The total energy you can extract is therefore the rotational energy that the rotor had before you connected up the dynamo, which you put there yourself by starting it spinning in the first place.

This is all completely trivial stuff. What was his point?

Dave

[Dave Rogers]

I would point out that there is nothing that can be " spun frictionless".

There's no physical contradiction in it, though. A magnetically suspended rotor in a perfect vacuum would be a fairly good approximation to a zero-friction bearing.

Dave

[catsmate1]

I would point out that there is nothing that can be " spun frictionless".
No does the necessary perfect vacuum.

I can see 2 flaws

1. The "external" equipment to keep it running (generating the superconducting magnetic fields, and generating the vacuum) will need more energy than this thing would generate.

2. Consider 2 snapshots of the system. One when it is lined up with 1 magnet in the ring, one when it is lined up with the next magnet. These are at the same energy level, so there's no reason why the system would move from one snapshot to the next
Yep.

[Dave Rogers]

I can see 2 flaws

1. The "external" equipment to keep it running (generating the superconducting magnetic fields, and generating the vacuum) will need more energy than this thing would generate.

No, they won't necessarily. Practically, yes, but in principle a vacuum can be maintained with no expenditure of energy. And in principle a current flowing in a continuous superconducting coil will continue to do so without loss of energy for ever; it's inherent in the definition of superconductivity. Neither of these is a fundamental physical flaw.

2. Consider 2 snapshots of the system. One when it is lined up with 1 magnet in the ring, one when it is lined up with the next magnet. These are at the same energy level, so there's no reason why the system would move from one snapshot to the next

But this is. And it's just a different way of stating the point that ellindsay beat us both to the punch on.

Dave

[DC]

magnetic friction.

[BenBurch]

The flaw is that it is a free energy machine!

By definition, there is no such beast.

However, you can make machines that harvest environmental energy in a way that is apparently free energy. The "Atmos" clock for example. Or any solar power device. Free in that the energy itself never had a price tag.

[Myriad]

Gah, one of my least favorite forms of pedagogy -- issue a completely incoherent description of a system and then say "find the flaw."

Let's consider those stationary magnets on the stator (the outside ring [but it's inside the glass] that doesn't turn). Which of the following describes them:

a. They don't really do much.
b. They provide a minute "push" to the magnets on the rotor (the rotating shaft and coil in the middle) as they pass.
c. They provide magnetic fields that generate current in the coils of the rotor (that being the only way the whole contraption could possibly generate the mentioned current).

Only one of these can be true. And b can be true only in a limited sense; if a fixed magnet provides a push as the passing magnet moves away, it also provides an equivalent push in the opposite direction (that is, add resistance) as the passing magnet approaches in the first place.

So the flaw is something like "if the fixed stator magnets aren't strong enough or positioned so as to generate any current in the rotor coils, then there's nothing in the system that generates any current that can be extracted through the wires; if the fixed stator magnets do generate current, that resists the rotation of the rotor (as the current is generated by doing work on electrons to push them through magnetic fields) so the rotor will soon slow down and stop; and in any case the stator magnets cannot provide any net push to the rotor magnets as they pass."

But it's easier and in a way more accurate to say, "the description is incoherent."

Respectfully,
Myriad

ETA: Cross-posted with everybody (except the OP)!

[AmandaM]

Gah, one of my least favorite forms of pedagogy -- issue a completely incoherent description of a system and then say "find the flaw."

Just to clarify, the teacher didn't come up with the description -- that came from some person on Facebook. The teacher was just quoting it in his status and asking his subscribers if they knew what the "significant flaw" was, beyond the obvious. (In this case the obvious is that there is no such thing as a free energy machine -- someone already suggested that.)

He does this on occasion, more for his own amusement, I think, than to actually see if we remembered anything from class.

[AmandaM]

A stationary magnet that pushes against a magnet on the rotor so as to speed up the rotor as it goes by will also push against the magnet so as to slow down the rotor as it approaches. Magnetic fields are conservative

I suspect this is the "significant flaw" he is looking for.

[Beelzebuddy]

I think the real news story here is a teacher taking on Facebook.

What, are high school students not stupid and immature enough to keep them busy these days?

[AmandaM]

I think the real news story here is a teacher taking on Facebook.

What, are high school students not stupid and immature enough to keep them busy these days?

The school is on break and the people who have commented on his previous updates all seem to be adults, some former students of his.

[Mr. Scott]

If we assume zero friction and perfect superconductivity then it should spin forever, though slow down if any energy is attempted to be extracted from it. The fatal flaw of schemes deriving any energy from magnets pushing or pulling is any energy derived from pushing will be lost from pulling and vice versa. There's never a net gain.

Here's the original perpetual motion magnet machine (http://www.kilty.com/graphics/magnet.gif). If the magnet can pull the ball up, it's too strong to let it go back down. All such permanent magnet schemes have this same fatal defect.

[gabeygoat]

I don't know why everyone's so upset with the teacher. What was his point? Well, maaaaaybe, it was to get people thinking, using their noodles and whatnot. Nothing wrong with that.
I love this forum, but one of my issues with it, is when people are like, "Well, this is easy to me, therefor it's a stupid thing to ask." How is that productive at all? How does that attitude promote science?

Sorry, /rant

[Dave Rogers]

I don't know why everyone's so upset with the teacher. What was his point? Well, maaaaaybe, it was to get people thinking, using their noodles and whatnot. Nothing wrong with that.
I love this forum, but one of my issues with it, is when people are like, "Well, this is easy to me, therefor it's a stupid thing to ask." How is that productive at all? How does that attitude promote science?

As the rather obvious main offender, sorry I gave that impression; I should probably try a little harder to remember that things that are obvious to me may be less so to people who don't have the benefit of my experience and training.

Dave

[gabeygoat]

As the rather obvious main offender, sorry I gave that impression; I should probably try a little harder to remember that things that are obvious to me may be less so to people who don't have the benefit of my experience and training.

Dave

Thanks for addressing my rant. It wasn't my intention to single you or anyone else out. It seems like a common theme in many of the threads on science. I can totally understand being wary of the many crackpots and woosters we get here. But, I feel sometimes the atmosphere makes it very hard to ask questions. Again, not singling anyone person out. I love to learn about science, but really don't "get" a lot of it such as physics and quantum mechanics. But I'm always hesitant to ask questions here. I think it is one of the reasons that Americans have a hard time with science. So many are afraid to ask questions, and asking questions is exactly what is needed.

[Travis]

The flaw is that word "free."

Eliminate it.

[Myriad]

While I agree that the magnets having no net "push" is probably the flaw he was looking for, I still think the lack of any provision for the thing to actually generate any current by spinning around is also a significant flaw.

[psionl0]

A frictionless generator should in theory spin for ever if it is not connected to a load. However, connect it to a load and it takes energy to turn it around. (You can test this for yourself by shorting the terminals on a generator and seeing how much harder it is to turn the crank around).

The explanation for this is that when a generator is not connected to a load, no current flows in its coil so the coil doesn't get magnetized.

[Puppycow]

As others have pointed out, the problem is that the term "free energy machine" implies that you would be able to extract more usable energy from the system than you put into it. This machine doesn't do that. As soon as you do anything to extract electrical energy from the system, it slows down. If you want to speed it up again you will have to add more energy again.

[AmandaM]

You can't design an arrangement of magnets that imparts a constant torque to the rotor with no energy input. A stationary magnet that pushes against a magnet on the rotor so as to speed up the rotor as it goes by will also push against the magnet so as to slow down the rotor as it approaches. Magnetic fields are conservative - the total energy change from a closed path through a magnetic field will be zero, so you can't make the rotor spin faster with purely permanent magnets.

I quoted ellindsey on a post and the teacher's response is "ding ding ding. we have a winner." So thanks :)

Sorry to post such strong evidence of my scientific illiteracy.:o This thread did, however, lead to an enjoyable afternoon (for me) of looking at previously suggested "free energy" machines and watching videos of some ex-hippy guy "levitating" steel balls. :)