G'day Ziggy,

Are you still working on the concept where you use a shield that prevents the magnetic fields of two like magnetic poles from being repelled and then when the shielding is removed extract energy from the relative motion?

If you are then it doesn't matter how you do it or what you use, it just won't work.

Again, the problem comes from the misbelief that you can produce a shielding system that stops magnetic fields dead in their tracks. You can't and any so called magnetic shielding systems work by redirecting or collapsing the magnetic field. In other words they don't stop or shield from magnetic fields, but rather redirect the field through them.

As such they are subjected to the same sort of magnetic effects that you are trying to shield from.

Ok, if you were to use some sort of highly magnetically permeable material to collapse the magnetic field around one magnet then while you positioned the shield you would have to expend a certain amount of energy to get it in position. If you were to then move a like pole near the shielded pole and remove the shield then yes the like poles would cause a repulsive force. However, you would have to exert a fair amount of force to remove the shield and that means you would need to expend energy. Now if you were to add up all the energy expended in inserting and then removing the shield it would be more than the amount of energy you could get back from the repulsion of the like poles.

I'm sorry to say it, but it doesn't matter how you go about it you can't get a net energy gain from any machine. The universe just doesn't work that way.

Regards masu.

You can indeed shield a steady magnetic field to any degree you specify (99%, 99.6%, 99.9999%), except you will never, ever, get 100% exactly.

The bad news is that it takes work to insert the shield and it takes even more work to remove it. In other words, not only is there no free lunch, but the waitress will steal all your change.

Your idea has been tried many times. It doesn't work. It cannot work. If you have maths training, X B = 0 for magnets.

ok... here is the problem with 'shielding' the magnetic field in order to obtain a 'disequilibrium' wherein you might be able to have magnets come in unaffected, but be repelled when exiting...:

1. ....the method employed for most commercial magnetic shielding is to encapsulate the item to be protected in a 'bubble' build using material that has very high permiability and very low hysterisis. this creates a huge low resistance pathway for any incident magnetic field to travel around instead of through the item to be protected. it is not tough to understand why something with high permiability would not work when attempting to shield two magnets from each other...

2...... there are substances that actually block, as in turn away magnetic flux. this trait is exhibited in diamagnetic materials. water is actually weakly diamagnetic. bismuth and pryolitic graphite are more diamagnetic, while super conductors can block essentially all of the flux..... sounds great right?.........it doesn't solve the problem

when diamagnetic materials bend the flux away, the material itself is repelled from the magnet, so no 'free energy will be gained, because the magnets will still require the same force to be brought into close proximity.

something to keep in mind when contemplating lines of magnetic flux, is that these lines do not just trail off into nothingness. the lines are more acurately modeled as loops that circle through the magnet, out one pole and back into the opposing pole. you may be able to push the fields or channel the fiels, or even overwhelm the magnet, but you aren't going to get lines coming out one end that don't reenter the other.

benbenben

G'day Ziggy,

I don't think you understand what we are trying to get across.

If you were to use a perfect form of mu‑metal you are not shielding or preventing the magnetic field from permeating free space but rather collapsing it through the mu‑metal. As a result the mu‑metal shielding is subject to all the usual magnetic forces of attraction and repulsion and that means you have to expend just as much energy removing it from it's intervening position as you would have moving the opposing magnet into place without it being there.

I'm sorry to say but there just is now way around the Law of Conservation of Energy, no matter what you do, how you do it or how complex the mechanism is you can never get back more energy than you put into it in the first place. That's just the way the universe works and if you wish to build something then you have to allow for this law.

• We can go to the moon and put men to work in space. This sounds like a question to put to my friends at NASA And Ask I will .

They will tell you exactly what we have, no matter what you do and that includes going to the moon and working in space you can't get round that pesky conservation of energy law. Mind you, as soon as you mention perpetual motion and getting more energy back than you put in you're likely to elicit fits of hysterical laughter and completely destroy your reputation.

When you're working with magnetic fields keep in mind that engineers and in particular electrical engineers like myself have been playing with magnets for a very long time indeed and we have an extremely detailed and accurate understanding of how and why they work, react and interact. It's also considerably more complex than can be explained here and just to understand the fundamentals as used in electric motors for example requires three separate semester long subjects which is about 162 hours worth of lectures and about twice that spent studying text books. Oh, and that's before you count the 108 hours of Calculus and Analitical Geometry for Engineers so all up you talking about five months of full time study withy your head buried in a mountain of text books.

By the way magnetism and diamagnetism come from two completely different sources. First off magnetism comes from electrons spinning on the axes. If you get all of the electrons spinning in the same direction then the rotating electric fields will interact accumulatively and give you the attraction and repulsion you get with the magnetic effect.

However, diamagnetism comes from the direction the electrons are orbiting the nucleus. If you get them all orbiting in the same direction then the orbital motion of the electric charges will produce the repulsive effect you see with diamagnetism.

That's also why diamagnetism is so much weaker than magnetism. With an electrons spin you are talking about an oscillation that is taking place over the diameter of the electron which is a very short distance and thus you have a strong force. On the other hand with diamagnetism you are talking about oscillations that take place over the diameter of the electron's orbit which is many, many orders of magnitude greater and hence produced a much, much, much, much weaker force. (note the ratio of manys to muches, it is actually relevant)

G'day gals, guys & gurus,

• ok... here is the problem with 'shielding' the magnetic field in order to obtain a 'disequilibrium' wherein you might be able to have magnets come in unaffected, but be repelled when exiting...:

Most of this has been said in one way or another, but I think this may make the physics a little easier to understand.

I gather your idea is to shield a moveable magnet from an opposing magnetic field until it is close then allow the fields to interact and propel the moveable magnet. Your idea being that you will be able to extract more energy from the outward motion of the movable magnet than was required to move it towards the fixed magnet.

Ok, the problem with this is that the magnetic shielding materials don't actually shield the magnetic field, they rather redirect it through themselves and basically collapse it. Now, the key word here is COLAPSE not SHILD and once the field is collapsed you can't extract any energy from it no matter how you arrange things.

Keep in mind, untold thousands of people have attempted to build perpetual motion machines and I have lost count of how many have been presented on CR4 but a guess would put it in the hundreds. Now, every single one of these so called perpetual motion machines have one striking feature in common and that is:

The don't smegging work!!!!!!

Sorry but that's just the way the universe operates.

Actually if you think about it for a moment you will realise that it's the only way the universe can work. Try this little thought experiment.

You have built a machine that returns slightly more energy than you put into it. So, if you feed the output back into the input you will have an infinite energy source. However, if you did you would have a system that would ultimately run away in an out of control energy source that would ultimately destroy the universe.

Since the universe isn't apparently a figment of my imagination it must exist, therefore, there can't be any perpetual motion machines, because if there were it would have destroyed itself and wouldn't exist.

Ok, it's a bit more convoluted than I initially intended but I hope this makes things a little clearer.

Regards, masu

Hi,

I support post 7 strongly (GA to you).

Regardless the intended machine will not work,

here my suggestion for "good enough" magnetic shielding:

As Mu-metal is very expensive (except if extracted as scrap) I prefer any steel with very low carbon content.

This has the benefit of:

very cheap (as used in deep drawing cars parts from sheet),

very effective with minor hysteresis,

not susceptible (as the Fe-Ni-alloys Mu-Metal and Permenorm) to stress and strain,

no necessity to heat-treatment below hydrogen at 1100°C.

Get some of the stuff - the lower the strength the better - in 1 to 2 mm thickness - cut and try.

If not good - too large residual magnetic field - we are talking about Teslas (?) to be reduced to nano-Teslas (?), take a second shield and insulate this electrically from the first shield.

If still not good enough then insert a copper or aluminum sheet (electrically insulated at both sides inbetween the two steel sheets.

The insulation need not be very good, as the voltage is very low - anodising the aluminum is perfect. Any non-conductive paint or glue with a sheet of paper or tissue inbetween is perfect.

With this you can bring the shielding factor to any desired value.

look to the literature about the probes to measure small magnetic fields: flux-gate, Foerster-probe, saturation magnetic probe, Josephson magnetometer.

Decide what you need and build yourself or get one from the surplus (military or scientific) market. Or get an outdated airplane magnetic compass - pretty sensitive.

Don't play with diamagnetic material - the available material data are much too bad.

Try and educate yourself - you will learn a lot.

Nothing is as effective as ones own experience.

RHABE