Prajna

Thanks @Mordred, I'm aware of the polarity shift, referred to as the Right Hand Rule, iirc, if you wrap your hand around a wire with your index finger pointing along the wire, that indicates the current direction, then we have the magnetic field and electric field perpendicular to the current, indicated by the middle finger and thumb. If that's the same thing you're talking about. But anyway, in the above example I am only discussing the change in energy of a steel sheet as it is attracted by a magnet situated above it. I don't think that in general terms we need to consider polarity shifts. I think I am getting closer to a reasonable understanding in the discussion with @exchemist.

This is a much more reasonable response, @exchemist, thank you. At least you understand what I'm talking about. So what is happening is that there is a movement of energy into and out of the magnetic field, much like storing energy in an inductor, I guess. That's what I was referring to as 'work', perhaps inaccurately. We might consider that the steel sheet is 'falling upwards' towards the magnet in its magnetic field, that when the steel sheet is on the table and the magnet is fixed 30mm above it there is a potential energy imposed by the magnetic field and when the steel is attracted up to the magnet then that magnetically induced potential energy is converted to kinetic energy until the steel sticks to the magnet. Now the magnetic potential energy has been converted to gravitational potential energy. Then if the magnet is an electromagnet and we cut the current to it the steel falls to the table, a conversion of gravitational potential energy to kinetic energy until the steel rests on the table again. Have I understood correctly? As an aside, I used to live in Chatham, Chattenden and Maidstone when I was at RSME and serving in the Royal Engineers. I spent a good deal of time at the Historic Dockyard in Chatham, where I drove steam cranes on the docks at the weekends. So I'm quite familiar with the area. That place is very interesting too. If you get a chance to visit the Officer's Mess at the dockyard you can see the vaulted ceiling that was built by ship's carpenters and is really the upside-down hull of a ship.

Ah, so there's no simple answer to my question, only answers that demand a couple of semesters studying physics and you guys are exercising your right of pedantry and hubris to dodge the question, or, as a layman might put it, you don't know the answer. No problem. So much for "Trust the science". @exchemist, thanks for the civil and helpful replies. The rest of you, meh.

Ah, I hadn't seen this, perhaps it was edited in after I read your post. Thanks for the correction on Ed's name, I should really have looked it up. Yes, fascinating guy. He did some seemingly miraculous things and free-energy-cranks have been arguing over his book(s) for years, suggesting they were written in cipher, maybe they were. I rather thought that if anyone would be considered a crank then Ed would be right up there. Nice to be disabused regarding that. Your curious fact is indeed curious, or certainly interesting. Whether I have enough interest to wade deep into relativity and QM to see it is another matter. If you can point me to general info about it that doesn't involve glazing over with esoteric formulae then I would certainly like to read it. I explained exactly that the magnet is fixed. Maybe it's been there for years. Did I suggest, insinuate or even hint that it's floating? Eddy currents? What does that have to do with my question? I want to know what, in the circumstances I described, causes the increase in the potential energy in the steel sheet that is attracted to a magnet positioned above it. Just that. Answer that. Simply and clearly and without diversion, obfuscation or irrelevance. Can you do that?

Ok, so it takes some work to lift and fix the magnet into place. But that has nothing to do with what I asked: what is lifting the sheet of steel I slide into position under the magnet? I don't lift it. Sliding it horizontally into position under the (fixed) magnet is a little work but it adds no potential energy to the sheet of steel. The magnet lifts the steel from its position below the magnet by magnetic attraction,which you insist is not work. The potential energy in the steel has increased since it has been lifted against gravity by the magnet; not by me, not by the (rigid and fixed) support but by the magnet. Something somewhere did some work and it wasn't anything but the magnet! When I slide another sheet of steel under the magnet (it's raised above where the sheets are slid under it, doesn't move, is fixed in place, so I really have to spell all this out?) You are speaking as if someone or something is lifting the magnet. In this example assume the magnet is fixed in place 30mm, say, above a table. I have a handful of small steel sheets on the table top, not directly under the magnet. I slide a sheet under the magnet, a horizontal move, and let go. What happens? Well in my world the sheet is attracted to the magnet and physically lifted off the table by the force of the magnet so that it sticks to the magnet. Say it was an electromagnet rather than a permanent magnet (didn't want to bring in electromagnets and let you guys complicate things further but necessary now in the explanation) and at this point in the experiment the electromagnet is switched off. What happens? In my world the sheet drops back to the table, its acquired potential energy converting to kinetic energy in the process. If you think the magnet did no work in that situation then I need a better explanation of how that can be since anything else adding potential energy to a system is doing work. Or am I wrong?

Are you saying that in fixing the magnet to its support work was done but when the magnet lifts a small sheet of steel,say, that is placed under it that no work is done? Are you saying that the support is doing work? In placing the sheet under the magnet then work is done, no problem with that, but that work, unless the sheet is lifted into position, has not increased the potential energy of the sheet, whereas when the magnet lifts the sheet the potential energy in the sheet has increased. What caused that increase in potential energy?

That still doesn't compute here, @swansont, maybe it's just me being thick. The object is lifted, seemingly by the magnet, and thus its potential energy has increased and surely some work must have been done to achieve that, n'est-ce pas? What did the work? Surely you understand what I mean and I hope you are not being pedantic with regard to terms. In this example (to remove ambiguity, I'm referring to a permanent magnet fixed to some structure above the object, say a small sheet of metal).

How does this relate to my response to @swansont above? Is it an attempt to answer that? My example refers to a permanent magnet rather than an electromagnet. It seems to me that the magnet is doing work rather than redirecting force. Or are you saying the magnet is redirecting the force I am using to hold the magnet up? What if the magnet is affixed to something? Interesting but off topic, I believe, @KJW

Absolutely it will stop with no input, I expect nothing else. If I hold a magnet above a ferromagnetic object the object (if it's not too heavy) will be attracted to the magnet. That has increased the potential energy in the object, so work has been done, has it not?

Turning the rotor merely provides switching for the magnets. Unless I'm mistaken, the torque required to do so will be determined by friction in the rotor bearing (and some trivial air resistance) and eddy drag on the finger that is in the magnetic field (and, balanced out, attraction into the magnetic gap on entry and exit from the gap). The output torque on the flywheel will be determined by the magnetic field strength of the magnets (and some friction, da dah, da dah). Where am I falling down on my understanding? The rotor doesn't determine the output except in terms of how quickly it effects the magnetic switching. Or is there some other principle at work?

Useful digression, thanks. My model says a magnet is always trying to complete its outside leg circuit by the shortest, lowest reluctance path. Therefore energy is not being created or destroyed, simply that there is a force whenever poles are separated and the force is attempting to reduce the 'size' of the circuit. As a gap between magnets is increased then the intensity of the force drops off (per the inverse square of the distance), and the converse. The 'energy source' never runs out because the force is always present when poles are separated. We can consider a weak magnet to have barely separated poles and a strong magnet to have (comparatively) widely separated poles; I'm not talking here of actual physical separation but just as a metaphorical way if considering it. When we separate two magnets there is a force between them in much the same way that if we lift something against gravity we are storing potential energy in the object. If the magnets are free to move then they will snap together (or fly apart if like poles are opposed) in the same way that when we drop an object its potential energy is converted to kinetic energy. In my device then, in terms of this model, with the rockers in the starting position, the magnets on the right are in the best arrangement (in terms of their magnetic field stress) they can achieve given the geometry in which they are restrained. Those on the left, because they are opposed with no mutual reluctance path, are arranged (limited by the restraining geometry) to the position where they offer the least obstruction to each other's magnetic circuit. If the rotor is turned 20 degrees then the situation is reversed and the magnets will rotate the rockers into the opposite configuration. No energy is created here, just sufficient energy has been input into the system to rotate the rotor, removing the finger from one gap and introducing a finger into the opposite gap. The movement is effected by the strength of the magnetic fields between the magnets. Using more powerful magnets should increase power out put but would also increase the eddy current drag on the rotor fingers, increasing the force required to turn the rotor. It is likely that the eddy current drag is always proportional to the magnet strength, I don't know and really it is this unknown that prompted me to post about the device here. This is what I need to understand, either practically by building and testing or, as I hoped to attain here, through an understanding of eddy currents and how they relate to field strength. Perhaps it is time for me to go look into transformers. By the way, another influence on the required rotor torque is that the finger will be attracted into the field as it approaches and dragged back towards the field as it exits but I don't include these effects since they should be symmetrical. If you can think of other influences on the magnitude of the required rotor torque then I would be interested to consider them (excluding such obvious and trivial things such as friction in the axle bearing). Thanks @KJW, it has been in the back of my mind. I have considered that there will be a reaction time between the finger exiting the gap and the magnets exerting their force on the rockers. It may be that at high rotation speed on the rotor the rocker arms may 'stall', or flutter rather than exhibit their full movement. The problem is that this is still a thought experiment, since I haven't built a device yet, so many things are just suppositions; things I have considered but only been able to come up with the best opinion I can achieve with my current practical and theoretical experience and a bit of reasoning based on that.

Well, I don't claim it to be a comprehensive explanation (just that the one I outlined above is more complete than the previous offering). I'm trying to present a (albeit much simplified) way of looking at magnetism that, perhaps, helps to understand what is happening with magnets. Thanks for the pointer to the wiki article, very interesting, particularly the idea of gyrators, which I had not come across previously. Gyroscopic effects being another favourite of free energy cranks, btw. The idea of pole coincidence is to explain how a magnet comes into existence and, in my model, represents the 'ideal' state of a material, exhibiting no magnetic properties outside the material itself. When the poles become separated, by whatever means, the material is constantly trying to return to that ideal state with its poles again coincident. If it can't do that then the next best thing is for it to complete its magnetic circuit in the most efficient manner - by the shortest, lowest reluctance path, including by attracting any ferromagnetic material in its local environment into a position where it offers the shortest path for the 'outside leg' of the circuit. Sure, this description doesn't attempt to reconcile with other models of EMF and MMF and falls short of attempting to incorporate formulae with which to quantify it, but it is simple and sufficient to understand magnetism on a broad level, much as using water flow in a plumbing system to illustrate the principles of electric circuits. Using it I can explain the interaction between the fingers on my rotor and the opposed magnetic poles in the rocker magnets by saying that when a finger is interposed between the magnets the magnets are offered a path by which they can reduce the stress in their magnetic fields by taking the path offered by the ferromagnetic properties of the finger - lower reluctance and a shorter path for the 'outside leg' of the magnets - thus attracting to the finger where they were otherwise repelling each other. It may not be a 'scientific' explanation but it is not 'wrong'.

Ok, I'll get on to reading that wiki article shortly but let me first attempt to outline more clearly and completely my theory (rather hypothesis) on magnetism: 1. All matter contains two magnetic poles that normally coincide. 2. In some substances it is possible to separate the magnetic poles in which case a 'magnet' is created. (perhaps this is possible with all substances, just we don't know how to do it yet). In ferrous metals, for instance, we can do this by exposing them to a magnetic field. I'm talking here on a macro level, there may be a far more adequate description at the atomic scale, your description of the alignment of magnetic domains being an example, but let's stick to considering it at the level of magnetic circuits for the moment. 3. When a magnet is created by separating the normally coincident poles a magnetic current is created, one 'leg' of which circuit runs between the two poles inside the, now, magnetic material. The other leg tries to complete the circuit via the shortest, lowest reluctance path it can find, normally the air surrounding the magnet,though this is a very high reluctance path but if there is no better path then it will do that; the circuit has to be complete whatever the circumstances are, you can't have an open magnetic circuit, according to my theory, which is why a monopole cannot exist (except I recently noticed an article that suggested magnetic monopoles have been created, oh well, maybe). 4. If the magnet, with its magnetic stress from the pole separation, is close to something that offers a lower reluctance path than the air then the magnet will try to include that object in its circuit, attracting said object to itself in order to shorten the path: what we see as magnetic attraction. 5. When we bring two magnets together with like poles facing both magnets we have really joined both circuits so that there are now four 'legs' to the circuit: the shortest, lowest reluctance legs running between the two poles in each separate magnet; the high reluctance, longest leg, between the extreme ends of the two magnets; and a leg interposed between the two magnets. 6. When we bring two opposite poles together what we are really doing is adding to the magnetic stress in the magnets, effectively further separating their magnetic poles. Now each magnet finds it more difficult to complete its circuit since the 'like' pole is adding to the reluctance in the 'outside' leg. So the magnet sticking to the beam is explained by the magnet trying to incorporate a low reluctance path and make that path as short as possible. For any faults this explanation contains, for me at least, it offers a useful way of understanding the behaviour of magnets. If it makes me look like a berk then no matter, I'm sure there is always a place for a free-energy-berk-crank, at least in some people's affections. (was replying via my phone earlier, which is why my explanation was less clear)

Ok, I hadn't really associated chemical bonds with electrostatics (which I tend to associate with Van de Graff generators and rubbing cats on perspex rods, etc) but I'll accept that chemical bonds are electrostatic. All the thinking about this device began while watching one of Robert Murray-Smith's early videos where he was discussing Wesley Gary's magnetic motor. He showed that if you place a thin keeper across the poles of a horseshoe magnet then if the keeper is longer than the span between the poles you will get additional poles that appear on the ends of the keeper due to flux leakage. If you then lift one end of the keeper off its pole the pole on the end of the keeper reverses. The way I interpret what is happening with the keeper is by thinking in terms of magnetic currents. As I see it, a magnet is always trying to close its circuit. Really it is a perpetual motion machine all by itself. There is a large magnetic reluctance in the air but the magnet will complete the circuit will complete itself via the air if there is no path with more permittivity available. The keeper offers a low reluctance path but if it is too thin to contain the full magnetic current then some leaks through the air surrounding the keeper. That leakage flux will be of the same polarity as the pole it is next to. When one end of the keeper is lifted off its pole you have effectively turned your magnet-and-keeper into one long bar magnet (or a kinky horseshoe magnet in this case) and the keeper becomes one end of that magnet - the opposite pole to the one it presented due to leakage flux. In my terms, a magnet will attract any object that offers a lower reluctance path than whatever is allowing it to complete its circuit currently (if you'll excuse the pun), that a magnet always completes its circuit via the shortest path with the lowest reluctance and the circuit is always closed. This need to reduce the length and reluctance of the magnet's circuit is what we observe as magnetic attraction. Now this understanding of magnetism may well be wrongheaded but it seems to me to offer a much better description of magnetism than the classical scientific one you offered, which doesn't really tell us anything about how magnets behave. I think Ed Leedskillin was the only guy who understood magnets but then nobody can understand Leedskillin (including me.)

Hmmm... I still feel like I'm being fobbed off somewhat. I consider a screw as being 'held', as it were. Actually the object that is being held by the screw is exerting a force downwards, due to gravity, while that force is being countered by the cohesive forces of the screw and whatever it is attached to. Electrostatic forces must be established and maintained. Concrete supporting something can be intuitively understood, as with adhesion and the steel wire rope you referred to. Magnetism does seem mysterious and different to other mechanical forces we encounter day to day, you can hardly blame free energy cranks for finding them irresistible. Thanks for the anecdotes of previous offenders, I'll have to look that old thread up. I suppose that part of the difficulty is in differentiating between force, work and energy.

Appreciated.

Fair enough, however energy is being employed to sustain the weight of the magnet against the force of gravity (at least I accept that gravity exists, count your blessings, you could be talking to a flat earther rather than a simple free energy crank). As I say, were I to hold the magnet in the air I would hope to have tucked into a decent bowl of porridge before the task, certainly if it was a heavy magnet. So, excusing my technical ignorance on the subject for a moment, what's holding the magnet there and what's the energy accounting?

Interesting. Thanks for another considerate response. I'm very interested to have a play with it and get a feel for how it behaves. You may be right that some energy can be passed back, I'll investigate. Hopefully I will be able to visit FabLab on Wednesday to see if they can help out with some 3D printing, laser cutting and sourcing nuts, bolts and shafts. It's not only 'free energy cranks' who don't understand magnetism. For instance, I've never seen a good explanation of what's going on when you stick a magnet to the bottom of an overhead steel beam. The magnet is obviously doing work, holding its own weight, certainly if I was holding up a magnet against the force of gravity it would feel like I'm doing work. So where's the energy coming from to do that work? If it's from the magnetic field then is the magnet's strength depleted by it? If not then why?

Thanks for the further response, @exchemist, I may be a free energy crank but I'm not claiming free energy here (though I don't rule it out), I consider this device to be an exotic transmission system - energy is put in by driving the rotor converted from rotational to reciprocating by the magnets and then converted back to rotation at the flywheel. Interestingly, power can only be passed forward through the system, rotating the flywheel will not cause the rotor to turn. There may be practical uses for such a feature. I'm an engineer rather than a physicist so my thoughts tend towards practice than theory. Maybe you guys believe it a waste of time to investigate but the idea looks pretty interesting to me. A friend who frequents another physics forum posted about it there (no mention of free energy or more out than in, he's a very sober and serious guy) and the thread was immediately locked. When he enquired about it the mods replied, "Don't drag rubbish out of the gutter on to this forum! That will never work, it's a useless machine and looks like a perpetual motion machine." How a physicist can say that something "looks like a perpetual motion machine" implies that such an impossibility exists with which to make a comparison. Oh well, a long period of lack of substantive response here is a far better reaction than was received here. Thanks for being patient and (mostly) respectful. ... "than was received there", sorry, can't edit the above.

I'm sure you're right because laws are laws, eh. But nobody seems interested to show a proof that the drag on the rotor is >= the force produced by the switching magnetic fields, so I'll reserve judgement and do some practical tests. It seems that is a more rapid approach to proving or disproving it than waiting for a physicist to do some calculations to show one way or another that my intuition is wrong. Quite how the thermodynamic balance is disposed in this device is not necessarily obvious and it may be difficult to express the above relationship, I don't know. I do know that there is a reflexive insistence on the laws of thermodynamics whenever such a device 'appears' to put out more energy than is required to run it but maybe that reaction is over resorted to. No probs, I'll just build it and test it and if it behaves as I imagine then you guys will have some explaining to do.

The idea is to use the magnetic force of opposed magnetic poles to drive an output. The magnets are switched by intervening a metal finger between them since inserting a metal sheet between two opposing magnetic poles causes them to be attracted to the sheet (since it has a higher magnetic permittivity than the surrounding air the magnets try to make a magnetic circuit via the metal). This effectively switches the magnets between repulsion and attraction, which causes the rockers to reciprocate between open on one side and closed, driving the flywheel via its diamond-shaped cam groove. It appears to me that the force required to turn the rotor (incurred in the main by eddy currents in the metal finger disposed in the field) may be less than the force produced by the magnets. I have still to build and test such a device, though I am close to doing so now that the design is pretty much complete, so I can't say for sure how it might behave. I thought that perhaps a physicist might have some feel for how the forces are balanced between eddy current drag on the rotor and magnetic force from the magnets. Attached is a simulation of the device running, which may help to illustrate the principle. Thanks for your question.

Here's a better picture:

Thanks for your response. You can test my assertion by folding a piece of card in half, attaching magnets to the ends of the flaps with their poles opposing and then slide a sheet of soft iron between them. The sheet will want to attract to whichever magnet it is closest to but you will notice that both magnets are attracted to the sheet. I believe that what is happening is that the fields of the magnets are attracted into the sheet since it has greater permeability than the air gap and that this effect is stronger than the repulsion force in the gap. Unless I've misunderstood what you were saying.