| Author | Message | ||||||||||||||||||||
     Raymond Liu |
Dear Mr. Field, I'm having trouble building this expirement. The magnets are so strong that when they snap together they crack and sparks come out. How do you even get the supermagnets apart? And I also made the graghte really thin and it won't float above the magnets. Is it because I placed the supermagnets in the wrong order? Please help me. Sincerily, Raymond Liu | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The pyrolytic graphite will probably float fine, even with cracks in the magnets, once you get the magnets oriented properly. They must be oriented with opposite poles next to one another, such as
Once they are in this position, the graphite will float if it is thin enough. | ||||||||||||||||||||
| Raymond Liu |
But how can I get them in that position if they repell? It is hard and even my dad can't do it. If you use a sheet of metal to stick it on there, it is really hard and the magnets move and just stick together. | ||||||||||||||||||||
| Raymond Liu |
You see, I didn't use a knife to make it thinner, I used a sharpening stone to sand it down until it was very,very thin. My dad siad that it was immpossible to cut it with a knife. I tried your advice and it still didn't work. I really want to do this for the science fair. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
It is not hard to arrange the magnets properly. If you have a compass, use it to find the north pole of one of the magnets. Place that magnet north side up on a piece of metal, so it stays in place. Use the compass again on the next magnet, to place it north side down right next to the first. The magnets will not repel, they will stick together, even without being placed on a piece of steel. Place the third magnet north side down on the metal, touching the first magnet. Place the remaining magnet north side up in the remaining corner of the square of magnets. The Pyrolytic Graphite cleaves easily with a sharp knife or razor blade placed against the thin edge. It is also fairly easy to cut using a sharp knife against the flat face, since this stuff is a pure crystal of the same stuff a pencil lead is made of, and is thus fairly soft. | ||||||||||||||||||||
| Raymond Liu |
I finnally got it to work! Thanks a lot!!!!!!! | ||||||||||||||||||||
| Jim Bradley |
I found a convenient way to find the north seeking pole of the 12 mm cubic magnets. I floated the bottom half of a plastic container for 3M electrical tape in a sink of water. I placed the magnets one at a time in the center of the container. If the poles are not vertical, there is a strong orienting force that will cause one side of the magnet to face north. I marked the north seeking side with a felt tip pen. I tested whether the pole is vertical by rotating the top (horizontal) surface 90 degrees to become a vertical surface. The difference is quite clear. Do not do this in a sink made of iron. The magnet may jump to the side wall or bottom. Also any permanent magnetism in sink may confuse the magnetic north direction. I had a convenient Corian sink to use. If I needed to find the N pole of the disk magnets, I would use a little tape or putty to stick the edge of the disk to the bottom of the floating container. One of the potential problems with using a compass to find the north poles is that it is easy to accidently reverse the polarity of the needle if the strong magnet is brought too close when the needle cannot rotate. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
Excellent advice. I have found that holding a magnet loosly in each hand, and then bringing them together (with the hands preventing them from jumping together and shattering), that the two magnets will prefer to arrange themselves with opposite poles towards each other. Since it doesn't matter whether you start with a north pole or a south pole (all we need is to alternate poles), you can then stack the magnets together pole-to-pole:
Now you know that all of the magnets are either north pole up, or south pole up. From here it is easy to arrange them to alternate in the square arrangement. | ||||||||||||||||||||
| elvin roman |
hi, i bought the PG and im having trouble making it float... i cut the PG in three slices and then cut it in half.. and when i put it in top of the magnets it doesnt float.. im not using the square magnets.. but i have some that are pretty strong..they sheets are really thin.. but i dont know whats wrong? im doing a presentation thurs so it will be very nice if i got it to work by then! att elvin | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
You say you are using your own magnets. I have no idea how powerful they are. Our 12 millimeter cubes are the strongest that can be made with current technology -- 48 MegaGaussOersteds. Most of the NdFeB magnets on the market or available at surplus houses are about 30 to 35 MGOe. You should also make sure that your magnets are oriented with alternating poles, as described in the text: N S S N | ||||||||||||||||||||
| W Giles |
Assembling 9 piece magnet levitation What is the pattern for arranging the 9 piece magnet set? I am not sure I understand how to do it from the 4 piece instructions. Thanks. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
It is the same idea -- the poles alternate:
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| W Giles |
In order to explain why the graphite levitates, I want to make a drawing of the magnetic fields. What is their shape? Then I want to compare it to the shape of "regular" fields that makes levitating magnets unstable. Thanks. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The field lines arc from north poles to south poles. The dimple between the poles is where the graphite rests. The humps of the fields are what prevent the graphite from slipping off. A single magnet has field lines going from the north pole to the south pole. If you try to levitate the graphite on a single north pole, the force slopes from the center outwards, like a hill, and the graphite falls off. With four hills, the graphite can rest between them, as a book resting between four balls. | ||||||||||||||||||||
| W Giles |
Thank you! Just to make sure I understand what you say, I would draw 4 humps, with lines going from each N corner to the adjacent S squares. It seems like each hump would be at the center of 4 squares, with the center of each hump on a corner of the center N magnet. Is that right? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The magnetic field is strongest at the centers of the poles. It doesn't matter whether the pole is north or south. The graphite will try to stay away from the centers of the poles. That is why the four magnet version has the graphite with the corners in between the poles. The nine magnet version has the corners aligned towards the farthest magnets, since they are farther away. Imagine hemispheres over each pole. That will give you a reasonable approximation of what the field strengths are. | ||||||||||||||||||||
| W Giles |
Thanks for your help! The project was a hit. We found arranging the magnets was quite easy using the technique suggested earlier of holding them in your hands and moving them slowly together. The magnets were indeed extremely strong, and we did crack one when they slammed together even with the earlier warning to be careful. To explain the physics, we made a model using clay to show the hemsipherical filed strenght at the dipoles rather than drawing them. This message board was great! | ||||||||||||||||||||
| kevin mc |
i was wondering dont you just set the graphite on the magnet and it will hover | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
No. If you place the PG on a magnet, the magnet will repel it, and it will be pushed off the magnet. It is like trying to balance a postcard on a stream of air. When there are four magnets with alternating poles, there are four centers of force pushing on the graphite, and it tries to escape by moving away from all of them, towards the center. | ||||||||||||||||||||
| Greg Nold |
There is another way to do this experiment, and the results are identical. I went to my local Sears Hardware store and purchased a set of carbon motor brushes, since I know that carbon is also diamagnetic. I clamped a brush in the rubber 'soft jaws' of my vice using just enough pressure to hold it still without crushing it. I took a hack saw blade and cut the thinnest slice of carbon I could without cracking it. When finished, I sanded the slice even thinner using sand paper, being careful to keep the thickness uniform over the length of the carbon slice. (Be advised -- sand the carbon over newspaper since it will make a black mess on the floor and on your hands!) I was able to end up with a perfectly rectangular slice of carbon that was slightly thinner than a standard credit card. When I placed this thin slice over the properly arranged cube magnets, the effect was immediate. I put the set up in my display case a month ago, and carbon slice has been levitated there ever since.... perfect stability! | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
Excellent! I think you will find that the pyrolytic graphite is not only much easier to work with, but will levitate about three times higher. The graphite crystals in the PG are all aligned perfectly. Those in carbon brushes are small, and aligned randomly. Since the diamagnetic effect is much more pronounced perpendicular to the crystal faces, and the PG is one big crystal, you get better results. | ||||||||||||||||||||
| Greg Nold |
Looking at the photos, it looks like the pyrolytic graphite does indeed float a bit higher than my slice of carbon. My slice hovers about its own thickness above the magnets, and the graphite seems to be about 3 times higher, just as you said. Still a cool effect though, and easily seen! I'm involved with another NdFeB magnet project now, but when I'm finished I'll purchase some of your pyrolytic graphite just to maximize the effect. Nice web page -- I commend your efforts. There needs to be more education in science, and your site definitely makes it interesting and fun. Greg | ||||||||||||||||||||
| Alex |
Is there a difference in the diamagnetism of PG and carbon graphite? There cant be much, because i managed to get a magnet in mid-air. Thanks alot, Alex | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
Pyrolytic graphite is about 3 times better than either bismuth or regular graphite. Regular graphite is not aligned -- the crystals are jumbled up randomly. Graphite is several times more diamagnetic perpendicular to the plane of the crystal sheets than parallel to it. Randomly oriented graphite does not have enough of the perpendicularly oriented crystals to make it as good as bismuth. The real test comes when you try to levitate ordinary graphite above the magnets. It is much more difficult than with pyrolytic graphite, and usually requires a more elaborate magnet arrangement that is less elegant (small bits of graphite between the poles of two attracting magnets held slightly apart). Getting a magnet to levitate using diamagnetism for stabilization is pretty easy. It can even be done using a person's fingers instead of bismuth or graphite, if the lifting magnet is strong enough. But levitating something other than a magnet is a little harder, and PG works best. | ||||||||||||||||||||
| Alex |
Is there any place other than yourself to buy PG? Y'know like walk in, find, buy, leave? And in the Bronx region...? Thanks again, Alex. P.S. I'm 13! | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
No, this is not the kind of thing you'd find in your local hardware store or drug store. That's why we offer it on the site. Another supplier is SPI: here is their web site. They want $70.56 for a 10mm by 10mm by 1mm piece. It's really nice stuff -- but it is over 40 times more expensive than what we carry, and it doesn't levitate any better. It's used for scanning tunnelling microscopes. | ||||||||||||||||||||
| Merle Ishtar |
Dear Mr. Field, I was just wondering if you could tell me what magnetic levitation is? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
It is lifting something up against gravity, using magnetic fields. In the context used on this web page, it is further constrained to mean that the levitation is stabilized by diamagnetism, instead of by some other force, such as touching a wooden dowel, or being held in place with a string. | ||||||||||||||||||||
| Merle Ishtar |
Thank you Mr. Field! | ||||||||||||||||||||
| Mihitomi Higurashi |
Dear Mr.Field, I am doing some research on Magnetic Levitation and I need to know some future uses of it.Could you please help me? Thank You! | ||||||||||||||||||||
| Matthew |
Mr. Field, Hi, I've surfed your site and its pritty cool. I got a levetation kit and some other kits and I was wondering what other uses there is for polyatric graphite? I have some left over and no more magnets to levetate it on. (Maybe levetating multiple peaces one over eachother occording to their size?) | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The PG won't repel PG. Diamagnetic materials repel magnets, not each other. However, you can build the first type of levitator, where the magnet is levitating, stabilized by two plates of diamagnetic material. Just because I used bismuth in the first one, doesn't mean you can't use a better diamagnetic material, like PG. The magnet floats higher with PG than with bismuth. | ||||||||||||||||||||
| Matthew |
I dont mean levitating PG with PG I mean making one float over the others on a magnet becouse thicker ones dont float as high and the thiner ones float higher. PG ___________ ========== |||||| |||||| Magnets There is two peaces of PG over the magnets, the thicker one floating lower (heavier) | ||||||||||||||||||||
| Matthew |
PG is carbon I wonder if I could use it in the H-Bomb project...? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
Try the two-piece levitation, and let us know if it works. Is there room under the thin one to float a thicker one? Will the thick one shield the thin one from the magnetic field? Let us know! And yes, the PG will work fine in the H-bomb project. So will a bunch of pencil leads. But the carbon rods were free... | ||||||||||||||||||||
| Matthew |
Hmmm.... I took a thinner one and put it on top, I took a thicker one and tryed the bottom.... I tryed puting the thinner one on top of the thicker one.... they all lay on top of eachother, this could be either becouse the PG blocks magnetic waves or it has a extremly light attraction to itself or according to the inverse square law the magnetic field dropps off alot at a certain point so all PG floats around the same spot.... | ||||||||||||||||||||
| Joey |
Hi, Could you tell me some future uses of maglev? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
I think your teacher wants you to be creative here. No one has a crystal ball. What do you think maglev might be useful for? Suppose really strong magnets become commonplace. Such a magnet can float drops of water, so they don't touch any container. Perhaps there are some kinds of chemical analysis or synthesis that would benefit from having no container. Perhaps growing crystals for X-ray diffraction studies. Maybe some of the experiments they currently do in space microgravity could be done more easily or cheaply using diamagnetism instead. See what other ideas you can think of. | ||||||||||||||||||||
| nkinnan |
You said that strong magnets can "float drops of water". Could you please explain that a bit more. Does that mean water is diamagnetic? It occurs to me that seeing water hover in mid air would be even more entertaining than watching PG do the same... | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
Water is diamagnetic. But since it is so much weaker than bismuth or graphite, it takes a very expensive electromagnet to levitate it. You can see pictures of the levitating frog (frogs are mostly water) and drops of water levitating in such a magnet. But that magnet takes amounts of electricity and cooling water that would supply a small town. | ||||||||||||||||||||
| nkinnan |
I can see from the diagram the the turns in this magnet are at a very small ratio to the current being pumped through them. Perhaps a similar effect could be obtained with many thousands, perhaps 10,000 turns of wire carrying instead of 50 amps, say 1 amp. Conservation of energy would seem to indicate that if using 1 amp for example, a higher voltage would be nessicary to achieve the same field density, or does the number of turns change that? Is this something obtainable by a hobbyist or is there a flaw in my logic? I can think of nothing more interesting that creating an "anti-gravity" field in my spare time. Would this be an achievable goal? In fact, with some rubber tubing, and a sufficient supply of mercury and liquid nitrogen, one could create a superconducting electromagnet (mercury becomes superconducting when reduced to very low tempratures) eliminating the electricity-to-heat conversion factor to 0 and greatly reducing the amount of power required. Being a superconductor, coiled into an electromagnet, the only energy loss through the system would be by induction in other nearby conducting objects, and the energy loss through the diamagnetic reaction with whatever is being suspended, thus I suppose that would depend on its weight. It seems to me it would be much less costly to run, but more difficult to build. What do you think? Achievable in either form? This intrigues me greatly. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The Bitter Solenoid mentioned in the link uses 20,000 amps, not 50. It has two coils, but for this discussion, let's pretend there is just one, with 214 turns. We thus have 4,280,000 ampere-turns around a 32 millimeter core. If your goal is 1 amp, then you will need to wind 4,280,000 turns of wire in the same volume as the Bitter Solenoid (if it is larger, you get less magnetic force). If the windings are on top of one another, the effect is a little bit weaker than if the windings are all in the first layer, so let's say 5 million turns will do. The wire has to carry 1 amp, so it can't be very thin. With 5 million turns of wire thick enough to carry 1 ampere, the size of the coil will get bigger than the Bitter Solenoid, so we will have to increase the number of turns to compensate for the outer layers being too far away from the core. Suppose we use 20 gauge wire (half a millimeter thick). We will wind the first layer 10 centimeters high, using 20 turns. There will thus be 250,000 layers, 125 meters thick, for a diameter of 250 meters. The average turn will be made of wire that is 400 meters long. Multiply by 5 million turns and we get 2 million kilometers of wire. The resistance of 20 gauge copper wire is 33.2 ohms per kilometer. The coil thus has 66.4 megohms of resistance. From Ohm's Law, we know that the voltage required to run 1 amp through 66.4 megohms is 66.4 million volts. Now we have a problem, because we have been assuming a thin enamel insulation on our magnet wire, but now we need insulation thick enough to handle 66.4 million volts. Our coil was already over an acre, and now we need to multiply that by about 50 times. The outer coils are kilometers away from the center, and probably don't contribute much to the magnetic field at this point. And we still need 66.4 megawatts of electricity to power this 50 acre device. So let's start over with superconductors. Mercury is not a superconductor at liquid nitrogen temperatures. We will need liquid helium. A better superconductor is niobium. But the problem with superconductors is that while they have no resistance, they still become normal conductors if they are placed in a magnetic field that exceeds some critical value. For the best superconductors at 1.8 Kelvin, this critical value is about 2000 Gauss, or 0.2 Tesla. The Bitter Solenoid described in the link was 20 Tesla, or 100 times the strength of what can be done with superconductors. The Bitter Solenoid is used because it is the best way we currently know how to make sustained high magnetic fields. For even higher fields, people use explosives to implode high current coils. However, these fields don't last very long, and neither would the frog. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
My friend Dr. John Edighoffer has pointed me to a paper on a 12 Tesla superconducting magnet using Nb3Sn alloy embedded in epoxy. The paper can be found here. It is not clear that the frog would survive the liquid helium any better than it would survive the trinitrotoluene. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The same lab that described their 20 Tesla Bitter Solenoid now has a 33.2 Tesla version, that goes to 60 Tesla when pulsed. | ||||||||||||||||||||
| nkinnan |
Well it appears I lack a great deal of knowledge in this area. I appreciate the time you took to go over all the aspects (problems) of my idea in detail. From my understanding of what you wrote, even with the "perfect" superconductor, the power requirements are staggering. I'm assuming that's because of conservation of energy (to create a magnetic field of x strength requires y electrons moving in a circular motion around and within z distance of the bore)? No way around that. 50 amp breaker? Hah! Then again... What about (given the "pefect" superconductor) just creating a single closed loop, a torus. No need for a coil really. Keep dumping energy into the coil, creating a sort of "magnetic capacitor" as more and more electrons begin to circle around the bore in a closed loop with no energy loss through resistance? Sort of like an inductor except closed. To my knowledge the only energy loss in such a system would be through induction in nearby objects and you could just continue building field strength by dumping more current into the loop indefinetly. An electro-magnetic capacitor... what do you think? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
While the resistance of a superconducting loop may be zero, it takes energy to build the magnetic field around it. So you put in a lot of electricity, and you get the 12 Tesla magnet discussed earlier. Now you close the loop, creating a short circuit. Presumably a safety fuse blows, protecting the power supply from destruction. Or the power is shut off, and the loop closed before the magnetic field can collapse very much. The collapsing field will start the electrons flowing again, sustaining the field. Or maybe you just put a loop of superconductor right next to the superconducting coil, so when you power up the coil, the magnetic field starts the electrons in the loop going, and they continue when the power to the coil is removed. So now you have a big permanent magnet. It is encased in reinforced epoxy to withstand the 10,000 pounds per square inch of pressure that is trying to blow the coil apart. It is constantly cooled with liquid helium to keep it below the critical temperature. The frog still freezes solid when you put it inside the coil. If the coil gets above the critical temperature, it will become a normal conductor with lots of current running through it. This will very quickly heat it up as the magnetic field collapses and dumps its energy into the molten metal and hot plasma. The 10,000 psi pressure will be greatly exceeded, and the laboratory gets bigger all of a sudden, with lots of extra fresh air and sunshine. I haven't calculated the energy density of a 12 Tesla coil, but it would be interesting to see if it even came close to a 20 gallon tank of gasoline. My guess is that we won't be supplating internal combustion engines with electric motors powered by collapsing magnetic fields any time soon. | ||||||||||||||||||||
| nkinnan |
You seem to be accepting yet dismissing my idea at the same time. I seek clarification. >>>>>> Or maybe you just put a loop of superconductor right next to the superconducting coil, so when you power up the coil, the magnetic field starts the electrons in the loop going, and they continue when the power to the coil is removed. <<<<<< Thus you could continue to build field strength indefinetly. Also, i'm assuming a "perfect" superconductor at room temperature which does not decompose into a regular conductor above a certain magnetic threshold. Seems the only problem to overcome is the magnetic force trying to blow the contraption apart. As theoretical physicists like to say: That's an engineering problem. Epoxy, whatever. The cooling is also an "engineering problem" if you don't have a perfect superconductor and the loop requires cooling to make it superconductive. I could imagine the torus encased in some sort of high strength material with an outer jacket contining any cooling liquid required while still leaving the bore exposed. A donut within a donut. Seems to me if you keep charging the closed superconductive torus loop with your seperate "charge coil" you could achieve any strength magnet desired, by slowly ramping up the current you are inducting into the loop. A hundred tesla, a thousand tesla, or more assuming the (lets again assume epoxy) isn't strained past its threshold for keeping the loop from exploding. The charge could similarly be drained from the loop through induction should you wish to reclaim the energy which you have stored in it. Theoritical applications include experiements with high-strength magnetic fields (previously unachievable), power storage for later reclamation, weapons use - break the coil and let the field collapse for an EMP bomb, etc. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The electrons in the superconductor are being forced to the outside of the coil by the magnetic field. This is what creates the force trying to blow the coil apart. However, it also affects the current carrying ability of the coil itself. The electrons are pushed to the outside edge of the conductor. As the field increases, the force pushing the electrons into the outer edges increases. The area where the electrons reside gets smaller and smaller. Eventually, there is no more room for them, and the current cannot increase. Worse, the electrons escaping that thin region heat it up, destroying the supercondutivity. You are assuming a perfect superconductor. That is like assuming you have three wishes, or assuming you can travel faster than the speed of light. Any conclusions based on an impossible assumption are suspect, and not generally useful. You can store energy in a magnetic field. However, the energy density is lower than gasoline, and there are expensive obstacles in the way of making a practical device. The people working with superconducting magnets are well aware of the possibilities, and when they find a practical way around the obstacles, we will read about it in Science, Nature, or Physical Review Letters. | ||||||||||||||||||||
| nick |
When Superconductor of type 2 levitates over magnet it uses flux-pinning effect. Does pyrolytic graphite allow any flux pinning? Is there any phenomenon of this kind? Actually, I have one idea and to make it work I would like to have pyrolytic graphite sample that would not allow any kind of flux pinning or magnetic field penetration of any kind. Do you have a picture of molecular structure of pyrolytic graphite and bismuth? please duplicate your answer to my email. Thank you for this great site and great job that you do!!! | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
There is no flux pinning with ordinary diamagnets. When you turn the pyrolytic graphite levitator upside-down the graphite simply slides off. With flux pinning, it would stay suspended underneath. The PG does not prevent all magnetic field penetration. PG is layers of hexagons of carbon. Each carbon in one layer is above the center of the hexagon in the layer below. Bismuth crystals are monoclinic. In bulk, the crystals are randomly oriented. See this page for a picture. | ||||||||||||||||||||
| nick |
thank you for link and explanations!!! as far as I understand PG cannot serve as a magnet shield. It just can float over the magnet. It allows some field penetration. How much penetration it allows (in % from total volume of flux)? Does it depend on the field orientation? I do not need exact numbers - just a general evluation. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
If you want a magnetic shield, use a piece of iron or steel. A diamagnet is like a mirror. The magnet sees its reflection, and the like poles repel. What are you trying to accomplish? We can help you better with more information. | ||||||||||||||||||||
| nick |
I want to build a magnetic bearing and I want to know if PG can serve in this way. I also do not want that magnetic field influence to other metallic parts what is a carrying capacity of PG? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The reason you need to split the PG into thin pieces is because it can't lift the weight of the 0.5 millimeters of PG in the upper half of a 1 millimeter thick piece. We are using the strongest permanent magnets mankind knows how to make, and the most diamagnetic substance known at room temperature. Even so, it just barely works. There are many patents on magnetic bearings. You can find out how to make one by reading some of those patents. Go to the patent office to read them. | ||||||||||||||||||||
| Jerry Ellison |
Tips/Discussion: 1) These little magnets are indeed very strong. I was surprised, the sellers are not lying. They will jump long distances if you let them. For me, this little surprise was pretty cool all by itself. I'm curious as to how big you can get them at reasonable prices? 2) The magnets from the kit are connected in a square, but they are not necessarily with alternating poles from the box like you are supposed to have them. For example, mine came with two magnets aligned n/s next to two s/n so than no poles were face up. It's simple enough to find which direction the poles are aligned, but some people might not think to check since they are already in a square pattern. Also, you don't have to find out which particular pole is which, only that the poles are sticking upright from the surface you lay the magnets on, and that they alternate. When you have them in the right position the effect is noticeable right away on the graphite. 3) Do the owners know if the pyrolitic graphite retains this diamagnetic properties in other states or does it have to be in the solid state that it was created in? Do you have any information on interesting effects from unusual shapes? Are there any studies on using it in experiments with the Casimir Effect? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
1. We can make them in dangerously large sizes. But those are not toys. They are very difficult to handle. They must be shipped in steel containers so they don't attach themselves to the truck, or interfere with compasses. As the demand is low, and the tooling costs can't be amortized over tens of thousands of magnets, the costs are disproportionately high. And did I mention that they are dangerous? 2. Exactly. 3. Graphite is most diamagnetic perpendicular to the orientation of the sheets of carbon hexagons. This is why pyrolytic graphite, which is basically a single crystal, is so much better than randomly oriented graphite, such as that in pencils and bulk graphite. It would be very difficult to make a liquid or a gas out of pyrolytic graphite, and the result would not perform anything like the solid form. Disks of PG allow rotation while levitating. Other shapes are certainly possible, but I am having a hard time thinking of any shape that is particularly interesting other than three: a. The square shape is nice because the levitating object is stable in all three axes (pitch, roll, and yaw). b. The disk is nice because it is stable in pitch and roll, but allows yaw (rotation), allowing it to be used as a bearing for lightweight spinning things, such as paper propellers. c. A narrow rectangle. If you place several of the four-magnet units in a row, the narrow rectangle will slide along the entire length. This can be used as a level, or inclinometer. The Casimir effect is independent of what the material is made of. Glass is probably the cheapest and easiest thing to make optical flats out of, and the Casimir effect needs something extremely flat. But I have no experience with the Casimir effect, and I would be happy to be corrected on any of the statements in this paragraph. | ||||||||||||||||||||
| R.W.T.Cooksey |
I found your site whilst pursuing a train of thought - How to make a (thin) compact compass. My main concern was the support pivot and achieving a level within a very low profile. A-HA - magnetic suspension I cried, then thought about the free rotation and the (bar magnet) indicator. Boo - Hoo. Then reading about the properties of PG on this board, I am wandering that if the PG is disc shaped (smaller than the base magnets array) and the needle is on top of the PG (and smaller), will it work ??? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The needle would get firmly stuck to the extremely powerful magnets a millimeter below it. Consider instead a 1 millimeter long compass needle. Attach it to a 1 millimeter bead of styrofoam. Place it in a 4 millimeter wide clear tube, standing upright, half full of water. The water will form a meniscus in the tube. The compass will center itself in the tube due to gravity causing it to seek the lowest point. The whole thing is no larger that the active element in a spirit level. | ||||||||||||||||||||
| Mark Ford |
I have tried this using Carbon Fibre sheet (STUCK ONTO WOOD SHEETS), I suspended a small powerful disc magnet between two sheets of Carbon fibre with a large magnet suspended above and it worked there is a very small stability band though and the distance from each plate is quite small but you can see through it. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
Normal graphite (randomly oriented crystals) is not as diamagnetic as bismuth. Carbon fiber is even less diamagnetic than that. Pyrolytic graphite is 3 times more diamagnetic that bismuth. The fact that you attained stability with carbon fiber sheets is quite a feat. If you replace them with bismuth or pyrolytic graphite, there will be a much better separation between the diamagnet and the magnet. | ||||||||||||||||||||
| Mark |
Would I be right in assuming that a Diamond could be suspended in the same way? since this is a single crystal of carbon? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
Diamond is a closed shell insulator, like silicon, sodium chloride, and silicon dioxide (quartz). These all have electrons with paired spins, and filled electron bands like a closed shell atom such as helium, neon, argon, etc. These properties make all of these things very weak diamagnets. Here are the relative diamagnetic strengths:
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| Mark |
I have been looking into Bismuth shot (used as 'lead free' gun pellets), it seems that most Bismuth shot is actually Bismuth alloyed with Tin. would there be much difference actual levitation difference between Tin-Bismuth shot and 99.99% Pure Bismuth? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
You are not likely to see any difference. The 2% or so of tin that is added will not make a noticeable difference. | ||||||||||||||||||||
| Mark |
Would Bismuth foil float in the same way as PG ? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
No. Bismuth is much too heavy, and is not as diamagnetic as pyrolytic graphite. | ||||||||||||||||||||
| david crockett |
I bought the nine magnet deal. I got all nine magnets together, three, three & three forming a square. the graphite is so thin you can near bout see thru it. It still will not float. I think I just threw away forty dollars for nothing. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
If you read the messages above, you will find that your problem is that the poles of your magnets need to alternate. In the case of nine magnets, that would be: NSN SNS NSN Check the poles using one of the methods mentioned above. Once you get the orientation right, it will float just fine. | ||||||||||||||||||||
| mark |
David, I found that, a good way to do this without using a compass is to put two single magnets together and then put a small piece of 'PG' (graphite) over the join between the magnets - if the PG starts to float then you have the two magnets correct, if it doesnt you need to change the sides that are touching each other until the PG does start to float when you put it over the join (it will not hover at this stage, just float & repel), repeat for the other magnets then carefully bring the pairs of magnets together in the same way and check for levitation and adjusting accordingly. It really does work! but they have to be correctly orientated in the special arrangment : NSN SNS NSN or SNS NSN SNS You dont need the PG too thin either (if it's too thin it doesnt work well) a millimeter or so thick by 10mm square is a good starting size. | ||||||||||||||||||||
| mike koscal |
I am doing the levatating pyrolytic graphite experiment for my daughter's science fair project. A couple questions we have: 1. Why is the special configuration needed for the 4 magnets as opposed to having all the North or South poles pointing up? 2. If we use 8 magnets and with the 4 magnet configuration but stacked two high, should the graphite float higher? 3. As part of the fair requirments we must try multiple substances. I don't understand why the Bismuth Foil would not expect to float. I thought somewhere it stated it was twice as dense as the graphite and 1/3 a diamagnetic so if the foil was 1/6 the thickness of the graphite wouldn't it levatate? | ||||||||||||||||||||
| Anonymous |
suppose that the ammount of bismuth that is melted and molded [see http://www.fieldlines.com/other/diamag1.html]is doubled and the distence between the two is also doubled should the magnets float higher someone please try this for me and post the results. | ||||||||||||||||||||
| Anonymous |
should the bismuth plates just be doubled in hight and should a bigger magnet be used.[see the above site] it would be helpful if someone tryed this too. By the same Anonymous as above. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
That site got their design from me. You can see the rounded bismuth was poured into a soda can just like my first one was. Doubling the amount of bismuth would not do much at all. The effect falls off rapidly with distance, and most of the lifting is done by the thin layer of bismuth closest to the magnet. To get better distance, you can do three things. 1. Use something more diamagnetic than bismuth, such as the pyrolytic graphite we offer in our catalog. 2. Use a stronger magnet as the lifting magnet on top. 3. Use a floating magnet that has a higher strength to weight ratio. Ours are 48 MegaGaussOersteds. The ones from Radio Shack are 27 MGOe, and barely work at all. The ones you get from disk drives are about 30 MGOe. | ||||||||||||||||||||
| Anonymous |
would you please suggest some sites that are related to this experement? still by the same Anonymous | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
The best sites are by my friends Martin Simon and Andre Geim. You can look them up in Google. Other things to Google are Meredith Lamb, and Pyrolytic Graphite. | ||||||||||||||||||||
| Anonymous |
thanks for responding! still by the same Anonymous | ||||||||||||||||||||
| C Richard |
Is this a possibility?: Diamagnetic levitation to create an electric generator? I'm thinking: Diamagnetic material on bottom (and maybe top with ceramic or electromagnet on top of that) with the rare earth magnet spinning. If windings of copper were placed around the spinning magnet, could the assembly be hooked up to say a very low watt lightbulb; would this work? | ||||||||||||||||||||
| Alessandro |
Hello, I'm doing some experiments... how would an electromagnet made to use it instead of your permanent magnets? Wich magnetic field in Tesla and wich inductance? Thank you in advance and compliments for your web-site! Alessandro | ||||||||||||||||||||
| Z Feirer |
How would one go about creating an electromagnet w/ a strength of 48MGOe? Is it even possible? | ||||||||||||||||||||
| Alessandro |
I have seen on the web that with (very) strong electromagnets they are able to levitate even frogs! I think diamagn strenght of a frog (and the weight) is very less than the phyrolytic graphite you supply, so I think with a strong electromagnet would be possible to do levitation! | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
Indeed. See this page. As for a 48 MGOe electromagnet, this one is even stronger. | ||||||||||||||||||||
| Z Feirer |
I've seen magnets like that before, but I was talking about one you could build at home. I don't need to levitate frog (although that would be really cool), but i hav a couple of ideas tat require electromagnets about the strength of the 12mm cubes you sell. | ||||||||||||||||||||
| Kevin F. Lynch |
Dear Simon, I am a biology teacher that has been teaching low level physics for a number of years I have your Gonzo Gizmos book and am curious about your explanation for rocket travel I thought their would be no "pushing" on the rocket firing chamber and that it was more of a case of rapidly throwing the rocket fuel mass out the firing chamber area and having Newton's third law take over. This would be similar to throwing items of clothing toward the middle of the pond inorder to have the reaction of moving toward the shore as the reaction Is this how it works??? Please respond and clear up this mystery for me by replying via my email Thank You | ||||||||||||||||||||
| Simon Quellen Field (Sfield) |
If you want a private reply, don't use the public forum. ;-) Suppose you plug up the nozzle of the rocket before you light it. The chemical reaction will still take place, and you now have a lot of hot gas under a lot of pressure. Pressure means pushing. Something is indeed pushing on all sides of the chamber. Because the pushing is equal in all directions, the rocket does not go anywhere. Now you unplug the nozzle. Suddenly, there is nothing pushing on the rear wall, since any molecules going that direction find no wall to push against. But there are still molecules pushing equally on all the remaining walls. The rocket doesn't go sideways because the left and right pressures are the same. But the top of the chamber is being pushed upward, and there is nothing pushing downward. The rocket goes up. Newtons 3rd law says that if I push on something, it pushes back with the same force. When you push your shirt towards the center of the pond, it pushes you back towards the shore. You can feel this push on your hands as a pressure. If you pushed on a wall with the same pressure, you would move away from the wall at the same speed. Whether you throw the shirt or push on the wall makes no difference, as long as the pressure you feel against your hand is the same. | ||||||||||||||||||||
| New Magnet Guy Unregistered guest |
Dear Mr. Field, Im very new to the world of magnets and i believe they have greater potential than anyone wil say. I had a few questions that i beieve you could help me out on. First, what kind of magnets are used in the production of electrity? Second which magnets are the strongest at repelling one another? Third, If i was usuing the magnets from question 2 what would be the push force of them? (What is the formula for how much a magnet can push free of resistances) If you could answer these questions that would be great thanx again. New magnet guy | ||||||||||||||||||||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 10 Registered: 12-2004 |
Any magnet can be used to produce electricity. Commercial power companies use electromagnets. Bicycle generators use permanent magnets. For magnets the same size, neodymium-iron-boron magnets are strongest, and within that type, the numbers range from 20 MegaGaussOersteds to 50 MGOe, usually named N20 to N50. The N50 magnets actually measure out to about 48 MGOe, and that is what we call them, and what we ship. | ||||||||||||||||||||
| New Magnet Guy Unregistered guest |
Maybe you answered my question and i just dont get it but, is there a basic formula to figure the magnet strength and how much weight that can push. Like how much weight could a 20 MegaGaussOesteds magnet push free of lets say air resistance? | ||||||||||||||||||||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 11 Registered: 12-2004 |
Free of resistance, it could push the entire earth. | ||||||||||||||||||||
| New Magnet Guy Unregistered guest |
WHAT??!!? Crazy... Ok i have anoher question. Are there any type of magnets that dont work until you give them an electric shock or something? Like, as soon as they get shocked they become magnetized? | ||||||||||||||||||||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 13 Registered: 12-2004 |
A coil of wire will do that. | ||||||||||||||||||||
| Anonymous |
I had my graphite levitated before, but I had the plastic spacers between the magnets. Then I noticed that the photos on your site don't have spacers between the magnets, so I removed them, but in so doing the magnets crashed together (I know...) and a corner smashed off one. Every since I'm unable to recreate the effect. Is it possible that the oriention of the field could have changed in the magnets ? | ||||||||||||||||||||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 20 Registered: 12-2004 |
Most likely you have simply mis-arranged the magnets. Make sure they are NS SN and they will probably work just fine. | ||||||||||||||||||||
| Anonymous |
Thinking about it, I can't see how it's possible to arrange 4 magnets in any other way than NS SN if they are to form a stable group because poles must alternate to attract eachother. | ||||||||||||||||||||
| Black Magnet Unregistered guest |
Right. Here's my method of alignment: Using strength and care hold two magnets apart from eachother and rotate them so that they repel evenly (a symetrical field). Now you know they are facing NN or SS, so rotate them both 90degrees and then invert one. Now carefully bring them together by pulling them apart as they close in. Repeat with the other pair and then join the two pairs by feeling the field and again pulling them apart as they close in to counter the acceleration you feel. If you get it wrong then you have a circular arrangement where the field forms a closed loop rather than a cusion with a dimple in the centre. | ||||||||||||||||||||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 23 Registered: 12-2004 |
With respect to the Anonymous post at 3:58: The poles must all be facing up. If you allow the poles to attract one another, then they will be facing sideways. The arrangement with all the poles vertical is not the most stable grouping, and will not happen by random chance. The magnets would rather assume an arrangement where at least one set has poles facing each other. I find it is easiest to arrange the magnets on a steel surface, or on a piece of cardboard on top of a steel surface, so that the magnets do not jump together. | ||||||||||||||||||||
| Anonymous |
hi i got this experiment and i cut the grafit so thin with a scalpel that you can see throue it it must easly be 0.1mm but the stupid thig will NOT flote and i would sllso like 2 know haow 2 arande 9 magnets so if flotes better i have 9 lol if ya can help pleez e maile me at ross123540@yahoo.com | ||||||||||||||||||||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 83 Registered: 12-2004 |
Have you read this message thread carefully? If it isn't floating, your magnets are not arranged with the poles vertical and alternating. Read the above messages carefully to see how to arrange the magnets properly. I am assuming you bought the magnets and the pyrolytic graphite from our catalog. Weaker magnets will not work. | ||||||||||||||||||||
| Jag Unregistered guest |
Was there ever an answer posted to C Richards question? "Is this a possibility?: Diamagnetic levitation to create an electric generator? I'm thinking: Diamagnetic material on bottom (and maybe top with ceramic or electromagnet on top of that) with the rare earth magnet spinning. If windings of copper were placed around the spinning magnet, could the assembly be hooked up to say a very low watt lightbulb; would this work? " Thanks, By the way Sfied, you're a genius! | ||||||||||||||||||||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 189 Registered: 12-2004 |
The levitating magnet has the poles vertical. Spinning the magnet would not change where the poles are, so there would be no power generated. If you did spin the poles end over end, the magnet would not levitate. If you spun the coils around the magnet, the drag would tip the magnet, and it would spin end over end, ceasing to levitate. Besides, if you are moving the coils, there is no advantage to having the magnet levitate in the first place. | ||||||||||||||||||||
| Anonymous |
Hi Mr Field, Instead of using PG, bundle of pencil lead works as well? If it does, must I align the leads in a straight line or clumping them together is fine? | ||||||||||||||||||||
| MadScientist Unregistered guest |
Mr Field, First, I would like to say that pound for pound, the PG lev is the most intriguing experiment I've ever done for the money... and for the benefit of the other viewers of the forum, I'd like to add yet another way to find the poles of the magnets... I actually bought 2 sets of the gauss rifle kits and just added on some PG to the order to give the purchase a little more bang for the buck. I noticed after playing with them that the balls eat away a little of the gold plating on the center of the poles of the magnets from striking them after several shots, visibly marking them with a grey dot. Granted, this doesnt tell you the polarity, but If one cant figure out which is which at that point, I would imagine that it couldnt BE explained.  This makes it really easy to find them if you are using the magnets for more than one purpose as I am. On another note, I rounded off one piece of the PG to see how it affected it, and of course found out about the Z stability issue (before reading it above), but in the process noticed that Eddy currents seem to be at play here, as graphite is conductive. I realize that the PG has very little mass, but also has very little surface area, and so air drag cant be playing much of a role. If Eddy currents are the cause, is there a way to minimize its effects so that a very efficient, lightweight bearing could be made (I want to make a miniature version of a much larger electrostatic motor that I built several years ago), and it seems that it could be possible if the 'friction' of the PG bearing is low enough. The basic idea for the entire shaft is to use a PG bearing on the bottom, and a needle at the top with another magnet above it to hold it erect, and to help support the weight of the rotor assembly in general. I picture a hybrid configuration somewhere in between the bismuth and PG projects. Do you think it would be practical to try? I ask first because the original was an extensive project, not anywhere as simple as the standard styrofoam cup/soda can type configuration. It roughly resembles the inside of the average toy DC PM motor. One other thing came to mind... how big would the main bearing need to be in order to be both stable and support the weight of the shaft (just a rough guess)? Oh - one more thing, on the topic of eddy currents - An interesting addition to the site would be the 'drop a strong magnet inside the copper pipe' experiment... Thanks for reading, I know its a bit windy... Steve | ||||||||||||||||||||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 324 Registered: 12-2004 |
In general, low friction bearings are used when the amount of energy available is very small, or the speed of the rotation is very high. Since neither is the case in your device, you might just use a normal bearing, and apply a little more current. The levitation devices I describe do not use strong forces to hold the material in place. It is easy to push the PG off the magnets, or to blow the floating magnet out from between the bismuth plates with your breath. This means that any device suspended in this way and rotating must be very well balanced, or it will produce sideways forces that overcome the bearing's abilities. The PG levitates because it is light. Adding weight will only work up to a point. The floating magnet works because it has a high magnetic strength to weight ratio. Again, adding weight reduces that ratio. | ||||||||||||||||||||
| MadScientist (madscientist) New member Username: madscientist Post Number: 2 Registered: 4-2005 |
Mr Field, I understand the problem with the bearing issue, and of course, it would only be able to support a minimal amount of weight. The key thing missed here, is that it is VERY fractional (if that term can be coined) horsepower, probably a millionth or two... The current version works solely from electrostatic fields, and there is about a 1 inch gap between the stator and rotor (chosen by materials available originally, not by choice) and it is somewhat more efficient than the design stated on the average web page, but barely. Without going into extreme detail, the original motor is basically a 1 liter bottle as the rotor w/ 3 poles sitting on a steel rod sharpened to a point, inside a 2 liter stator w/ 2 poles. It runs nicely (up to about 1000 RPM, at which point imbalances start to show and it flies apart) on anywhere from 15-30KV @ only uA. The micro version will probably only be about 2 inches tall, and 1.5 inches in diameter, and I'm thinking would not run near as fast because of stability issues in the bearings, as well as shorter dielectric gaps, so the supply voltage would be lower. I'm using aluminum foil for the poles. I would be happy just getting it to spin at all (20-30 rpm?) Ever seen the web sites devoted to fly-powered airplains? It is the same type of thing, trying to get physics to agree with you on a very delicate level. I just want something that can spin at about the rate the average solar-vane does, no real use, other than to know it is spinning completely hovering in mid-air. Dont forget that some of the weight will be held up by the needle. Steve | ||||||||||||||||||||
| MadScientist (madscientist) Intermediate Member Username: madscientist Post Number: 36 Registered: 4-2005 |
What was I thinking? Coined? Forgive me people, brain-farts are a common occurence in my world | ||||||||||||||||||||
| victor Unregistered guest |
Regarding levitation of water - I saw a previous post about the levitation of water, and I just wanted to mention that water has indeed been levitated using NdFeB magnets. Granted the volumes are very small, but it has been achieved. See the article here: http://physicsweb.org/articles/news/8/9/3 I am trying to replicate their experiment on my own, but have been unsuccessful so far. I am currently using 1/8" x 1/4" x 1/2" NdFeB magnets of grade 35MGOe. I arrange them so that their like poles are facing each other, similar to the setup from the article. However I haven't seen any levitation. I am thinking of using graphite powder to see if I can at least get that to levitate, but have had no luck with that either. I am using typical artist's quality graphite powder. My next thought was to use pyrolytic graphite, but due to the size of the device, I am thinking about grinding it into powder. What do you think? I am also thinking of buying higher grade magnets, but I don't know if that would make the difference between levitation or not. | ||||||||||||||||||||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 360 Registered: 12-2004 |
The magnets in the article are a quarter of a millimeter high. The drops are so small that they would float in air for a long time just on their own, much like the drops in a fog or a cloud. They are small enough to be subject to Brownian motion. The magnet simply traps them. The full article also describes a device using 2 millimeter high magnets, so our tiny magnets may work. They are 50 MegaGaussOersteds, and thus might be better suited than your 35 MGOe magnets. The substrate is steel, and should be easy to come by ;-) The slit is 1 quarter of the height of the magnets (up to 0.4 times the height), so you will want the 2mm magnets to be 0.5 mm apart. They have even levitated microscopic grains of bismuth, so the powdered pyrolytic graphite should work fine. Other graphite may have contaminants that make it magnetic enough to stick to the magnets instead of repel. | ||||||||||||||||||||
| victor yeh (victor) New member Username: victor Post Number: 1 Registered: 5-2005 |
Yeah, I found out the hard way that my graphite was not quite pure. They were sticking to the poles of my magnet. =( I was wondering if you know of any magnets out there that are even higher grade than the 48 MGOe magnets in the catalog. Still, yours are the highest grade of magnets that I've seen so far, so I am going to place an order for your tiny magnets. As for pyrolytic graphite powder, I only saw whole pieces of it for sale, so I will probably grind it up with sandpaper or something. (That won't make the graphite less diamagnetic, right?) I'm not sure if the steel substrate is needed for levitation. I think they used it for electrodes that manipulated the droplet, and probably as something to mount the magnets on. Thanks for the all the input--I really appreciate it. | ||||||||||||||||||||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 362 Registered: 12-2004 |
Our latest batch of magnets are N50. As the technology improves, we will provide the best available. PG is anisotropic -- the diamagnetism is higher perpendicular to the cleavage plane than parallel to it (all very pure graphite is like that). So the powder will flip to present the lowest energy profile, which will be the lower value for diamagnetism, which is closer to that of bismuth. But it makes up for it by being much lighter. | ||||||||||||||||||||
| AnotherAnonymous Unregistered guest |
Hmm, so from what you say Simon... PG powder would actually be *harder* to levitate than just very pure randomized graphite (like pencil lead), as PG would orient to present a lower energy profile than is possible with RG (unless you could powder it down to molecule size pieces). So... make some powder from non-ferromagnetic pencil lead. A good way to test the weak diamagnetivity of such is to levitate a magnet between PG or bismuth plates, and then poke at it with a various types of pencil leads. Whichever ones repel it the most (without touching) are the most diamagnetic. Some may attract it, avoid those. I got a bunch of 1/4" graphite welding rod, some rods have enough impurity to lift a NIB magnet, others are diamagnetic enough (in slices) to float like PG over NIB magnets, in all 3 orientations, odd! If I have time, I'll try some of the diamagnetic rod in powder form over some NIBs | ||||||||||||||||||||
| victor yeh (victor) New member Username: victor Post Number: 2 Registered: 5-2005 |
I was afraid that would be the answer. In that case, I should probably just buy the graphite rod to make my graphite powder then. It would be a waste to buy PG if its powdered form will not levitate as easily as RG. As for the thickness of the magnets, since they used very thin magnets to create a high magnetic field gradient, do you know how can get some thin magnets like that? I'm guessing that nobody makes magnets that thin due to brittleness, so that means we would have to find a way to do it ourselves. Would it be possible to cut/sand the magnet down and then coat it again to achieve a thin magnet? | ||||||||||||||||||||
| MadScientist (madscientist) Intermediate Member Username: madscientist Post Number: 40 Registered: 4-2005 |
In theory, wouldnt the particles of any powdered form of graphite just orient themselves in such a way that they no longer are repelled by the magnets, and simply give in to the force of gravity? Particularly the PG since it is 'polarized'. As for the levitation in all 3 orientations, one would assume that it is random enough that no matter what direction they are facing, there is always a repulsive force there, given that there is something to support the mis-aligned particles, such as a bonding agent (I would imagine the force produced would be reduced by about a third however, as opposed to PG?) | ||||||||||||||||||||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 364 Registered: 12-2004 |
PG is not "harder" to levitate than mined graphite. It will generally levitate better, because of its purity. Mined graphite, or worse, graphite that has been powdered and then mixed with clay, as in pencil leads, has impurities that make it heavier and less diamagnetic. In any powedered graphite the particles will align so as to levitate least, but they will still levitate better than any other material. The pyrolytic graphite will work better than anything else you will be able to find at room temperature. | ||||||||||||||||||||
| AnotherAnonymous Unregistered guest |
"So the powder will flip to present the lowest energy profile..." Now, in powder PG that would reduce the diamagetivity to a lower value than that of randomized (pure, not mined) powder, no? Since it is the individual graphite (sheet shape) molecules that are repelled, and if they are randomized, then they can never be all vertically aligned to the magnetic field, and would actually have more levitation than PG. Hypothetical of course since most pure graphite is PG, but if you had pure random graphite powder, it theoretically should levitate better. Imagine a bunch of spheres (say, 10 micron) of graphite, in PG and in random. The PG spheres would tip over, but the randomized ones wouldn't generally. Since the horizontal diamagnetivity of graphite is lower than the vertical, the randomized ones would levitate more, and hence be easier to levitate, no? As for thin magnets, you can get N50s down to 0.5mm here: http://engconcepts.net/List_Of_Disc_Magnets.asp | ||||||||||||||||||||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 366 Registered: 12-2004 |
No. Any particles small enough for this experiment will be single crystals, and will align to present the lowest energy profile. Impure crystals will weigh more and be less diamagnetic. Note that we are talking about invisibly microscopic dust grains here. You will need a microscope to see them. The pyrolytic graphite powder will still be the best levitator. The half millimeter thick magnets you mention are magnetized the wrong way. They are disks that have their north and south poles on the flat parts of the disk. You want a quarter millimeter thick magnet with the poles at the thinnest part. The disks have the poles at the thickest part. | ||||||||||||||||||||
| AnotherAnonymous Unregistered guest |
victor said: "I am thinking of using graphite powder to see if I can at least get that to levitate, but have had no luck with that either. I am using typical artist's quality graphite powder. My next thought was to use pyrolytic graphite, but due to the size of the device, I am thinking about grinding it into powder. What do you think?". Somehow I doubt he is getting single crystals. Besides, if they are single crystals, they are aligned anyways, and are basically the same as PG. So the only advantage of PG would be purity. And the site has N50 1mm magnet discs .5mm thick. Magnetized through the thickest part that is still only 1mm. There are some 1.5mm x 5mm magnetized through the length too. The webmaster will also sometimes do custom orders if asked nicely. | ||||||||||||||||||||
| jason Unregistered guest |
hello i am doin a science fair for my school and it is all about is it possible to make a mini hover board using magnets? i have gone futher into this but i just cant seem to fine out why this wont work, can you please email me back with some reasons why i cant get a board with a magnet on it to levitate from the magnet on the platform which is on the floor. note that the magnets are both on north pole. thank you. jason sparks. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 482 Registered: 12-2004 |
Read about Earnshaw's Theorem. You can make your hoverboard out of pyrolytic graphite. See this page for more information. | ||||||||||||||||||||
| Charles Van Neste Unregistered guest |
Simon, In regard to what was stated about pyrolytic graphite as a magnetic shield, if it can repel the magnetic field of strong magnets, would this not be a form of shielding? True some field lines will continue to penetrate through, but a good percentage of them would be repelled; similar to strong magnet against a weak magnet. If you had a layer of pyrolytic graphite next to a layer of high permeability/high saturation material I don't see why this would not make a very nice shielding. The high permeability/high saturation material will absorb those field lines that don’t get reflected by pyrolytic graphite. This could be done to reduce the thickness and weight of shielding metal when in close proximity of intense fields. Does this seem correct or is there a flaw here? Thanks, Charles | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 514 Registered: 12-2004 |
Magnetic fields are not like rays of light that can be reflected. A magnetic line of force goes from the north pole to the south pole of a magnet, no matter what is placed nearby. Some materials conduct magnetic fields better than others. A steel object conducts much better than air, so the lines of force go through the steel instead of through the air. The air then has much less of the field going through it than before, since the field is now concentrated in the steel. Diamagnetic materials do not repel the field, the field is simply not conducted through them as easily as through air. So the field lines go around the diamagnetic material to get from north to south, since that is the lower energy path (more lines can fit in the same area). It is somewhat like an island in a river -- the water flows around the island because that takes less energy than going over the island. But the water is going to go past the island -- it is not all reflected back uphill by the island. A piece of steel moves towards the magnet because by doing so more field lines can go through it, lowering the energy of the field. A diamagnetic material moves away from the magnet because that allows more field lines to crowd in closer to the magnet, again, lowering the energy state of the system. Since there is a finite amount of magnetic flux going from north to south, once you conduct all of it through something like steel, there is no more flux to detect outside of the steel. This is why you can put a magnet inside a steel box and not detect the field outside of the box. | ||||||||||||||||||||
| Charles Van Neste Unregistered guest |
Simon, I think I'm starting to understand but not fully. Let me brake this up into groups so its easier for you to correct my erroneous statements. 1.) I realize magnetic flux travel north to south. In ferrite materials when a magnet is present, the electrons, which are unpaired, begin to spin in unison creating a magnetic dipole that is opposite to the field applied. This causes the attractive nature of ferrite metals to magnetic fields. This is also what causes a permanent magnet to stay magnetized after the source has been brought away (the electrons continue to spin in unison.) 2.) As I understand it, diamagnetic materials do the same however their electrons set up dipoles of the SAME pole as the applied field (some what like eddy currents at the atomic level.) Causing a repulsion effect which is why the pyrolytic graphite will "roll" off either of the poles of a magnet. When the same pole of permanent magnets are brought together, the magnetic flux lines do the same thing, they try to go "around" each other to get from north to south. As you push them together, the field lines "squish" causing a force as the try to go around each other. 3.) I assume that if you took a piece of pyrolytic graphite while it was levitating and tried to press it down, you would feel the same kind of force you experience from permanent magnets that are facing the same poles. Only the force from the pyrolytic graphite would be much much smaller. Is this correct? Does this happen? 4.)What would happen if a piece of pyrolytic graphite is placed inbetween an N48 magnet and a piece of nickel/iron alloy? Would the flux lines just wrap around PG and pull the metal toward the magnet as if the PG wasn't there? Or would the PG reduce the amount of pulling the metal would see? From your earlier statement it would seem the earlier would happen. However, with my current thinking, I feel that there would be a small reduction in the amount of force the metal would see. Please correct me and thank you very much for your time Charles | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 516 Registered: 12-2004 |
1. Several misconceptions here. Electrons have a quantum mechanical "spin" and it carries angular momentum, but it is quantized, it is always there, and it is either up or down, no matter which direction you look at the electron, unlike a spinning top or the earth, where you can tilt your head and make it look like the north pole is a few degrees off from "up". There are no ferrite metals. A ferrite is an oxide, and is ferrimagnetic, unlike iron or nickel, which are ferromagnetic. This is all covered in the first chapter in the book (and on the web). 2. More misconceptions. In a diamagnetic substance near a magnet, the magnetic lines of force are farther apart than in air. Think of a bubble of air in water, rising away from the attraction of gravity. The bubble is not repelled by gravity. The water just falls into the space where the bubble is, and the air in the bubble moves to occupy the space where the water used to be. The magnetic lines of flux are closer together outside the diamagnetic substance, and farther apart inside it. The lines of force on the side of the diamagnet opposite the magnet are in a high energy state (farther from the magnet than they would be if the diamagnetic substance was not there). They can "fall" towards the magnet if the diamagnetic substance moves away from the magnet, just like the water can fall if the air moves away from the earth. So, just as the air bubble moves away from the earth to allow the water to find a lower energy state, the diamagetic substance moves away from the magnet to allow the magnetic lines of force to get closer to the magnet and achieve a lower energy state. 3. The force on the PG is enough to keep it above the magnet. When you push it down, it springs back up. Magnetic repulsion falls off with the third power of distance. Diamagnetic repulsion falls off with the fourth power of distance. 4. The PG would spit out sideways like a watermelon seed, being repelled by both the magnet and the steel, which has become a temporary magnet while in the magnetic field of the permanent magnet. | ||||||||||||||||||||
| Charles Van Neste Unregistered guest |
Ah that clears some things up. Thank you again for your time. Thanks, Charles | ||||||||||||||||||||
| ilija Ilievski Unregistered guest Posted From: 62.220.217.86 |
Is it posible to do this expirement with electromagnets and a lead instead pg? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 641 Registered: 12-2004 |
Electromagnets and a what? | ||||||||||||||||||||
| ilija Ilievski Unregistered guest Posted From: 24.171.76.44 |
lead duh | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 642 Registered: 12-2004 |
I don't understand what a lead is in this context. I can't even tell if you are referring to the element with atomic number 82, or to a tether, or to a single wire used to connect electronics. If the latter, why only one, and why no mention of a battery or some electronics and a sensor? Please describe more fully what you are asking about, so someone can actually help you. A full paragraph provides enough redundancy that we can figure out what you mean despite spelling and grammar errors. In fourteen words you have managed to make two spelling errors that we can easily figure out, and a grammar or spelling error that we cannot figure out. If you want help, you will have to provide more information in your questions, and pay a little more attention to your ability to communicate. | ||||||||||||||||||||
| T Scott Unregistered guest Posted From: 216.146.125.30 |
i have a question about pyrolytic graphite. if you placed a piece between two magnets would it break the magnetic attraction between the two. Like if you would stack them ns|pyrolytic graphite |ns would the two magnets still attract to each other between the pyrolytic graphite or not. thank you | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 652 Registered: 12-2004 |
Only by a tiny bit. More of the field would go around the PG, and less through, but it would all get there. If you want to block a magnetic field, put it in a steel box. | ||||||||||||||||||||
| T Scott Unregistered guest Posted From: 216.146.125.30 |
thank you very much | ||||||||||||||||||||
| Aaron Unregistered guest Posted From: 70.242.171.227 |
I'm doing a science project for physics and want to test different materials for (different strengths of) diamagnitism. I know that PG is good stuff, and bismuth is next but what are some other diamagnetic materials? Great site by the way, best deals on PG I've ever seen. | ||||||||||||||||||||
| Anonymous Posted From: 144.134.89.240 |
Check the above messages, you question has already been answered | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 673 Registered: 12-2004 |
To save you the trouble:
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| Anonymous Posted From: 219.95.252.119 |
I am having trouble with the magnet spinning between two pieces of pyrolytic graphite, separated by a small piece of wood. Can you explain more detail? | ||||||||||||||||||||
| Ben Dover Unregistered guest Posted From: 204.73.103.253 |
I am doing a science fair project using your directions for the levitating magnets. I was just wonder what some of the applications to real life it has. I know that levitating magnets are being used for trains, but do they use levitating magnets for anything else? Ben Dover | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 674 Registered: 12-2004 |
It is the same setup as the previous levitator (the one that uses bismuth). You just replace the bismuth with the PG. | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 675 Registered: 12-2004 |
There are displays that levitate merchandise for store windows. Some levitators are used as inclinometers. | ||||||||||||||||||||
| FrancisD (Unregistered Guest) Unregistered guest Posted From: 67.180.42.104 |
Boy you (Sfield) are one hell of a patient guy! I bought the PG with 4 magnets and the levitation works perfectly (I obtained the N-S orientation using a conventional magnet). I split the PG in half and then half again using an ordinary old swiss army knife. My only comment is that these tiny magnets are very very very strong - My kids are 8 and 12 and separating these magnets is tough for me and will probably be impossible for an average 8 year old. Also, just to underscore, when these puppies decide to come together, they rip right at each other and little fingers could get badly bruised! I am still going to let them play with these though because this levitation is "too cool for school". | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 733 Registered: 12-2004 |
Place the magnets on a steel surface, such as an old Altoids tin or the top of a tin plated steel can. That way the magnets will stick to the steel, and not go flying off or pinching fingers. The other advantage to the Altoids tin is that it can act as a container for the whole project. | ||||||||||||||||||||
| JerryWasHere (Unregistered Guest) Unregistered guest Posted From: 66.189.152.139 |
1. Has anyone done material properties of Super Cooled Pyrolytic Carbon? 2. Has anyone tried to make Pyrolytic Diamond from Pyrolytic Graphite? 3. Has anyone tried to make Pyrolytic Graphite and Bismuth foil layers together as a sandwiched substrate? Thanks Jerry | ||||||||||||||||||||
| anom (Unregistered Guest) Unregistered guest Posted From: 24.15.85.118 |
what if you cut the pg in to a triangle instead of a square ? what woudl happen would it spin? | ||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 856 Registered: 12-2004 |
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