New Test of J.Nordberg's 'Field Reversing Sphere' Experiment

No mistake. If, given axially symmetric currents in sphere or other body of revolution, there is any variation at all from field that would apply with straight wire substituted, one could have spinning 'free energy' magnets. No need for a complete field reversal. You seem despondent rather than spurred on with excitement. But I can understand why.

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I'm trying to envision this. You could place a bar magnet such that the center of it crossed the field curl switchover point, thereby applying torque on both ends in the same direction?

 

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Err, if the curl "switches over" at the Equator, the resulting (net) torque is....zero. The torques aren't "in the same direction", they are in OPPOSITE directions so they cancel each other. Wheelchair philosophy and physics don't jibe.

 

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Did you use WolframAlpha for that response or AskJeeves?

I'm trying to understand Q-reeus' comment about theoretical perpetual motion, not how Physics actually works. This isn't something found in textbooks so you wouldn't be able to discuss.

 

LOL, wheelchair philosophy ain't physics RJ. Opposite torques still cancel each other, even in the fantasy world you live in.

 

If Nordberg's experiment works as he claims it does do you agree that perpetual motion would be possible? If so, please explain how. If true I obviously consider this the death knell for an already dubious experiment.

 

You more or less have the basic hang of it - if by 'same direction' you mean same moment arm about a pivot.
[Edit: when I wrote above, was thinking of the 'radial' configuration of two bar magnets with like poles butting together (basically, a linear quadrupole config.), and attributing that to your bar magnet. So sorry, but a straight north-south bar magnet would NOT experience a net torque there. In that respect Tach is right. But see examples I give elsewhere to show achieving non-zero torques leading to 'overunity devices' is a consequence of Nordberg's supposed field configs]

Actually, my confidence all along has been knowing the differential form of Ampere's law, and curl - as in the usual properly defined understanding of that term, is key. That there is zero curl B everywhere outside of any current-carrying region guarantees spinning magnets, and 'field reversal', cannot happen. But on the ultra-slim chance Nordberg is right and that YouTube demo is legit, best press on regardless, yes?

 

Tach, the use of word 'curl' has been used freely and sloppily in both threads on this topic. The proper definition: http://en.wikipedia.org/wiki/Curl_(mathematics)
is quite distinct from what should be better termed field circulation sense. Latter is what I believe RJB was meaning. If it truly happened a la Nordberg, there would be radially directed actual curl B all around the sphere equator. But of course there won't be - imho!

 

I know exactly what curl means.

\(\oint_C \mathbf{B} \cdot \mathbf{d}{\ell} = \mu_0 \iint_S \mathbf{J} \cdot \mathrm{d}\mathbf{S} \)

as a direct consequence of:

\(\mathbf{\nabla} \times \mathbf{B} = \mu_0 \mathbf{J} \)

and of the Stokes theorem. In simple words the circulation of the magnetic field along a closed loop is equal to the surface integral of the current through any surface resting on the loop.

Hard to figure out what he means since he's incapable of formalizing his musings in precise, mathematical form.

 

Sure and I wasn't implying you didn't. It was generic statement about how Nordberg's terminology has been adopted all too freely by various folks here.

Aw come on - give the poor bugger a break now and then.

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You will notice I and most others are enclosing 'curl' in quotes to signify this. Curl does have more than one meaning, such as the 'curl' of a lock of hair or the 'curl' of the field circulation. I can't believe Tach would fixate on some pedantic detail rather than contribute anything to the bigger picture. So unlike him

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Nope because, according to Stokes theorem (see above) it would imply that the electric current through the wire reverses itself about the Equator plane, a physical impossibility. In addition, as showed by Norberg video, the two compass needles point in opposite directions, meaning that the torques exerted on them are opposite, so , a needle placed on the Equator would not move at all, exactly my point. To make matters even worse, you cannot make an electric motor using a constant magnetic field, you need a time-variable one, otherwise the rotor does NOT move continuously (a magnetic needle STOPS as soon as it aligns itself with the force lines of the field). So, no matter how you slice it, you are wrong.

 

No, the crank has gotten all the breaks in the past, his account is depleted.

 

Christ on a stick, your reading comprehension is deplorable. *I* am making ZERO PREDICTIONS here. Nordberg claims that X, Y and Z are going to happen; Q-reeus claims that this will lead to perpetual motion, if true. I'm asking WHY it's true. You seem to be saying that if Nordberg's claim were true, Q-reeus' observation is not..?

 

No, I am saying that you are an ignorant who doesn't understand that:
1. opposite torques cancel each other
2. you can't get a motor using steady state magnetic fields
3. nothing to do with Nordberg claims, has only to do with your crackpot claims

You are confusing your wheelchair philosophy with physics.

 

My claim in #39 & #41 relates not to just the existence of a torque on a magnet, which we all agree can exist for immersion in a magnetic field completely free of actual curl B. That just requires some angle between field and magnet axis other than zero or 180 degrees. It relates to that over a complete revolution of magnet or assembly of magnets (say mounted like radial spokes on an axis), the torque will or will not sum to zero net energy gain, depending on whether there is or isn't presence of net curl as in ∇×B. Hope this clears up any confusion as to what I was saying earlier.

 

As soon as the needle aligns with the lines of force of the magnetic field, the motion STOPS. Meaning that you can't get a "motor", let alone a "perpetuum mobile" from the Nordberg setup.

 

I hope you're right on this one Tach; just the laws of probability say that you should be eventually, right?

 

You need to get out of your philosophy wheelchair and take a physics class. You may want to start with intro to electromagnetism. Mind you, you will need to get intro algebra and intro calculus before.

 

We seem to be in disagreement here. I agree, and obviously have been stressing this point, that in actuality there will be no such magnet-motor effect. But precisely because Nordberg's setup cannot generate what he claims. If however his claim of field reversal were true, that represents a clear violation of Ampere's circuital law. We would have regions of finite curl B in vacuo, for a steady current flowing. And that in turn very much would allow a perpetuum mobile as I described. If there is doubt about the latter - remember - hypothetical situation, please consider carefully the situation where a uniformly radially magnetized magnet is mounted freely on an axis aligned with the net curl B vector of a 'field reversal' region. You say there will (or rather, would) be no torque in that case?