I did some experimentation recently. I rigged up magnets with some duct tape to try and get an idea of force required for separation of magnets attracted at the face.
I used 1/4" by 1/8" disc magnets I purchased at Hobby Lobby. By using a sport drink bottle and water, 2 magnets attracted together required approx 20 oz of water to separate them. Next i tried the same fixed magnet but this time taped 2 magnets together in attraction to test for separation force. 2 magnets vs 1 magnet came out to 30 oz of water.
Now 20 oz of water is 591.58 grams and 30 oz is 887.22 grams. The sports drink bottle with tape is 40 grams. So 1 magnets was 639.58 grams and 2 magnets was 927.22 grams.
Now in effect by doubling the magnets the force required to escape did not double. 927.22 - 639.58 = 287.64. with a second magnet i added less than half of the original weight it needed to break a 1 on 1 magnet hold. My kitchen sink rig will not support a 3 magnet set up. I will actually need to construct something for the purposes of charting the mass needed to break the pull. i am hoping the diminishing return effect continues, to the point where a device could be build to abuse this property. The downside is using water when the system breaks free, it tends to slosh around while attempting to catch the container. If this continues I will have to measure them in an offset manner( like a staircase) as well, trying to get same side polarity to stick out for a chain pull. And then measure end forces.
3 variables are key to any design. Mass, Velocity, and breaking force. the kenetic energy equation has all of these built in. E sub k= 1/2 (M x Vsquared). And trying to get E sub k greater than the breaking force. If the magnets have diminishing returns, then the longer the track the more velocity and at somepoint velocity should eclipse the barrier in linear motion.
Does anyone else out there have raw data like this? Or maybe point me to a websitre that has the data?
It sorta makes sense, the second magnet has a larger distance to the opposing one. Or, perhaps more accurate, the heart of the 2-stacked magnets is further away than it was with one.
If you'd use one wide magnet on one side, and mulpiple small ones side by side against it, your mileage might vary.
I might assert that you have to measure from the center of the magnetic masses rather than the faces... since the 1/r^2 falloff is technically from the center of (mass/charge/magnetic moment)?
And while you're at it, if you can confirm/deny that magnetic attraction is stronger than repulsion ( http://www.youtube.com/watch?v=8sUpFc-0yg0 (http://www.youtube.com/watch?v=8sUpFc-0yg0) ) would be great :)
Lets not jump too far ahead:D Attraction and repulsion is actually acceleration and deceleration. As a magnet approaches opposite pole, it goes from a weaker field to a stronger one and accelerates. Then it hits the sticky spot and decelerates as the opposed poles try to attract the object moving past. Most OU builds are done this way with attraction faces coming together. The difference is they actually dont touch as my testing is doing. So the force required to break the hold is actually less. So my 640 grams for a single magnet contacted with another magnet, using gravity, is quite a bit of joules when calculated. But non touching is less force. So with the same 640 gram mass ( if the magnets can pull it), would require less velocity, since the breaking force is lowered. In reality trying to get a stator to speed up to 9.8 m/second^2 is not an easy feat to match the same velocity of gravity.
As for measuring from center I have 24 -1/4 by 1/8 inch magnets if you line that many up in one big stack and put a magnet in the center(on the side of the cylinder), it takes almost no force to separate the magnet at the center compared to the ends. After i do all my end tests, I can try the same set up but breaking the center of the stack.
I would have to theorize the diminishing return of weight is actually due to the fact the magnets are not 1 magnet. The faces being attracted to each other are actually reducing the over all force of the ends. Basically it takes some energy from the overall system to keep the stack together. the only application i could see resulting from my tests is a stack that attaches and then releases because it could not support its own weight once energy it lost from the contact in forming a "new system". And I fear what such a device would actually do to the magnet since attaching is very close to impacting. And we all know how bad that is for magnets. Mind you this is all speculative till I get some more numbers done.
As for testing repulsion. The only rig I can think of would be a tube with a magnet( tube sitting vertically). And another tube introduced inside the first. With a magnet in repulsion inside of it. Both being fixed to their respective tube. the second tube could have a large container, for adding wet sand for example. Piling it up till the magnets contact. then measure the volume of its sand and calculate its weight. This would act much like compressing a spring.
Okay then the other bit of trivia I can add... (and ya I'm probably missing the ballpark entirely if where you're actually at)
while playing with the green magnetic field paper, there is a 'bubble' at the ends of the magnets, and if your magnets are smaller than this bubble, then adding more magnets will increase that strength, but more internally are diminishing returns... Hmm I don't have great illustrations of this but
This is a 1"diamget by 1/4"high cylinder magnet on its edge
https://www.facebook.com/photo.php?fbid=219204778100955&set=a.210482342306532.52736.100000343030096&type=3 (https://www.facebook.com/photo.php?fbid=219204778100955&set=a.210482342306532.52736.100000343030096&type=3)
This is the field on it which extends about the same as the radius of the magnet, if I therefore stack 5 together then they really stop contributing to the end field...
https://www.facebook.com/photo.php?fbid=219204634767636&set=a.210482342306532.52736.100000343030096&type=3 (https://www.facebook.com/photo.php?fbid=219204634767636&set=a.210482342306532.52736.100000343030096&type=3)
yeah the catch 22 of all this is every magnet is different. I dont have a magnetic viewer. But I would be curious to see a single cylinder field next to the same size cylinder comprised of smaller magnets, especially the lines it makes from end to center mass. But with every magnet being different, you solid magnet could be charged with 1.2 lbs of pulling force and the individual smaller ones might not have the same force . its something hard to prove given the randomness of the magnets creation. This is why I m doing weight tests.
the difference comes from the fact a single magnet is one piece everything about the magnet on the molecular level gives it its properties. Iron does not have a field untill you touch it to a magnet. then it becomes apart of the magnet. it gets its field impressed onto it. I dont think stacked magnets are that representation. They do not impress their fields on one other. They divert and contort the field. but in the end they are 2 fields stuck by attraction and the ends not touching have field diverted and contorted to them . Part of the field must be sapped to maintain the attraction. So the overall field should be getting smaller, with the end being boosted diminishing as more field is used to hold more magnets together. If my tests show a diminishing weight, Im still not certain if it is proof of my theory as to why it happens.
I cant really see anything in your pictures :X
After rereading what You and I have posted(Dex), I wanted to take a minute to re- explain the course I am going down. I never recognized your comment on the reduction of force from center mass of the magnet. I didnt mean to ignore that fact, it does play a part. But as I stated, a stack of magnets has to use energy from its field to stay together, otherwise they "should" fall apart. So in effect distance plus sapping field to maintain a stack will lead to a very strong end, as well as the minimal force to break the stack. You are in the ball park area of my thinking. If a stack of magnets has such a large force to pull, and very little force required to break it in half, could one not pull with the full force of the large stack. Now the only way to break that force is to use some of the momentum gained to break the center of the large stack. This would occur as the moving magnet approaches the sticky spot. I imagine some kind of hinged sleeve on the stack, Now force used to break the stack is now less because with a hinge we are using leverage. So now we have distance, overall field sapping, and leverage which should reduce the amount of energy to break the stack quite nicely. Once the stack is broken , the new lesser pull is decelerating the moving object much less than the original full strength pull used to accelerate. In a nutshell trying to conserve momentum. So imagine a track that is the initial velocity, and these large hinged magnets that attempt to boost acceleration as well as an attempt to conserve momentum at the same time. I hope I explained this well enough. I did not just want to go all willy nilly buying stuff and trying to make it happen. With the shear amount of magnets, I figured it was best to gather some data.
I believe i stated a way I want to try and manipulate magnetic fields and the numerical effects shown in weight or a force. That is a magnetism test.
@ microcontroller: If you actually read the posts, mass and weight are being used to test the maximum field strength of magnets in certain physical positions. Unless you know of some secret mystical way to test the strength of a magnetic field, there isnt another way. It is true a magnetic field technically is not apart of the magnet. but the field would not exist without the sub-atomic and the atomic structure of the magnet that created the field. How do you get magnetism without a mass or a magnet? My tests using weight( mass and gravity as a constant) are to find the limitations of the magnetic field. I am a layman, and knit picking over a definition label, will really get you know where with me. Your 2 posts have brought nothing fruitful like Dex's posts have.
Yes magnetic field do exist on the atomic level etc etc. But 99% of them are balanced or atleast the pair up and form molecules. Magnetism in the form of a magnet is a moleculue that forms a magnetic field around it. The molecule is the mass. Hence a magnet. A magnetic field just doesnt pop out of thin air. If it did the overunity mystery would be over. You say a magnetic field exists without a mass. A magnetic field cant exist w/o some mass supporting it. If you have the plans to create a magnetic field out of thin air with no mass, please do share it.. Every magnetic field I can buy at a store will have a mass attached to it.
Please go somewhere else your blithering drivel and lack of factual or even logical support, or lack of even a link to show some multi billion dollar experiment to support your claim. Trolling is not wanted in this topic.
If it bothers you that much about a term being used wrong get a moderator to change the header. But I am willing to bet they give less of a hoot than I do.
I suppose next you have a bridge to sell me, but you lost the deed to it too. Like I said previously I cant by a mass-less magnetic field. When I can, your blathering will have a point. But thus you say alot and have nothing to show for it thus far. Your mass less magnetic field is completely irrelevant, since it is not easily attainable to be used for the little overunity devices. You may be correct( giving you credit even though lack of proof), but still irrelevant. It doesnt matter what I believe or not, this is irrelevant also. I have what I can get to work with, and they all have mass. Your point is taken but mute as it is irrelevant. Now please go troll somewhere else.
@ fester
If the magnetic material is exposed, and in direct contact with one another
-- such is the case with ceramic ferrites, iron and soft iron magnets
The magnets act as one, and the results are much closer to the expected doubling in field strength.
In the case of coated magnets, like neodymium, and certain ceramics, or plastic coated magnets
There is no physical connection between the interface. and there lies a gap between each magnet that has to be taken into account in this type of experimentation.
I absolutely agree smokey. Would you also agree the field strength is lost from field being used to keep the stack attracted together?
Quote from: Fester on January 23, 2012, 09:36:36 PM
I absolutely agree smokey. Would you also agree the field strength is lost from field being used to keep the stack attracted together?
In the case of coated magnets - Absolutely yes.
with magnets, where the magnetic material is in direct contact, then generally no, the field-lines through the interface transmit unrestricted and not much energy is lost at the interface.
Yes my magnets are coated. Almost everyone uses them, so I should have said up front though. Secondly I would like to point out, my fluid ounces are US fl.oz. I dont think the old english imperial fl oz is used anymore, so I didnt see a reason to state as such.
There are advantages and disadvantages to doing measurements like these, with a liquid.
adjustability, adaptability, accuracy of measurement,
But, there are trade-offs for that, which can affect the accuracy of the results, cause inconvenient situations, ect. - which, im sure you have already experienced.
I guess the important question i have to pose here, is this...
if there are variances in forces due to the liquid being in motion, there are variances in your magnetic field, because of the arrangement of the coated magnets.....
What exactly is the point in stacking them in a non-symmetrical fashion, i.e. 2 on one side, one on the other..
Are you really learning anything by attempting to do that in this particular manner?
1) There are solid mass measuring methods, that would get rid of the water problems
2) If you insist on using asymmetrically stacked coated magnets, you need to learn how to incorporate that into the magnetic equation. Otherwise, the best you can ever hope for, is to plot an exponentially curved line, by experimenting with varying field intensities. Which, i believe, was conquered thoroughly nearly 200 yrs ago.
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Now, the other thing is, what exactly are you measuring?
break-away force? from an accelerating field? (gravity)
Where is the time factor?
there is no time, on the magnetic side of the equation, but when you translate that into the physical world, and gravitational fields, the moment of inertia, and duration of subsequent acceleration have to be incorporated into the problem.
I see, how you want to draw some sort of similarities, by mass comparison, but what you are instead actually measuring, is a unique quality of those particular magnets.
This is their " holding" or "lifting" strength. in most cases (except when you stack them asymmetrically)
This number is proportional to the Gauss of Tesla rating of the magnet, In industry you see this number rated in lifting lbs, or holding lbs
This ratio is not consistent from magnet to magnet, nor is there a unified scale to convert gauss or Tesla to lifting lbs, its ...... sort of like magnetic efficiency., some magnets are better lifters than others.
[Note: The above applies mainly to coupled pairs or sets of magnets,. not to be confused with another "lifting strength" value, which DOES display a consistent ratio between Gauss/Tesla and the ammount of paramagnetic material it will lift - paramagnetic induction.]
Yes water is a very poor measuring device, with the sloshing etc. And true no 2 magnets are alike, So any stack created would have to have its own force testing done. I wrote in my 5th post about what I was attempting to try and do. I may not have been to clear.
I want to take a stack of magnets. The more I stack, I get a stronger field on the ends. If Im not mistaken the field is the same size the the lines actually are condensed more to the ends. Now the longer I make this stack, the weaker the center section gets. Much as dexor stated with some obviously well known equation. With that sack all connected, there is a very large force. now we move object furthering its acceleration/ momentum by this very strong pull until gets just shy of the "sticky spot". An arm attached to the moving object could apply leverage at the outer most spot of the stack. This will take way some momentum outright. But breaking the weakest spot and using leverage( friction existing) would minimize it. This should result in a lesser drag effect than the pull we put in at the sticky spot. I am hoping this is not a zero sum effect. I am trying to do a conservation of momentum. Many tracks run with with excellent velocity, untill the end of the track. This would move the sticky spot for the track as a whole onto the stacked magnets. So stacked, it would be strong enough to pull off the end of the track, break the stack to a lesser force, and have to objects attraction to the start of the track be stronger than the remaining attraction of the broken stack.
It may be more beneficial to have a stack of magnets, and make the break away point 3 magnets in from the track. Its a stronger pull at that point, but would give increased leverage at the opposed end.
I hope this explains the path I want to go down.
ok , i think i understand where yur going with this...
To achieve yur goal, we're going to have to move yur understanding of the magnetic field to the next level. And by doing so, im going to have to upset the "time" assumption of Einstein's special theory of relativity........ Whis is ironic, because the very same equation, explains the interactions of the magnetic field lines, irrespective of time...
ok,.. when the field lines are close together, i.e. the center of the magnetic field,
acceleration is at a maximum, velocity of the magnetic energy-points is at a mininum (lenz), and the attraction force, (sqrt (distance)), is at a maximum - meaning th eentirety of the "field" is in the center where the field lines merge.
at the ends, where the field lines are separated to their maximum distance, acceleration is at a minimum, because, velocity is subsequently approaching the speed of light, and the magnetic energy-points are attracted back around to the center.
Magnetically speaking, the center is where the field intensity is at a maximum, the magnetic energy-points are slowed down because of attraction force. repulsion and momentum of the combined energy-points keeps the entire field in constant motion. in the center they vortex around each other. So the effective "outside" field experienced is virtually 0. AT the center, the particle experiences a maximum acceleration force and begins its journey back up to close to light speeds. It is important to note, that while each invididual magnetic energy point can never travel at speeds greater than c , They exist in a complete loop, and therefore, propegation of the magnetic field occurs instantaneously, across an infinite distance. There is no speed restriction, and while intensity diminishes at the ^2 of the distance, a magnetic field propegates throughout the entire universe instantly. A field here, can affect (to some minute degree) things in a linear path on the other side of the universe.
The external effects of the field, occur at the ends, because the field lines (paths the magnetic energy points follow) are separated north and south, at a distance.
The size and shape of the field is going to change your effective outside "0 point".
This is a logical fallacy to label this the point of least magnetic resistance, because it is simultaneously the point of greatest field-line density... but the cup must be both half empty and half full....
The classical understanding of magnetic fields, basically pertains only to the effect of those fields on physical objects. Not to the field itself. So when you have multiple fields interacting, in a purely magnetic interface, you have to take into account, the entire field, not just the point of interaction.
bcause changes on one side of the field, affect the opposite side, as well as whats going on in the center.
So what is your conclusion based on this? Not going to say I 100% understand this .. yet.
well,. if your attempt is to avert the sticky spot
by passing the magnets through a central "0-field" region of the magnet stack, then resume the 'driving action' of the magnetic motor,
i would arrange the magnets in a manner like, they would be a machine, in operation.
and focus on where the "0-field" shifts to throughout each step in the cycle. this will also give you an idea of how that relates to the changes going on at the outer ends of the field.
If you are looking for a consistent energy value, of the particular magnetic pair
Repulsion offers a more accurate depiction.
an ammount of mass lifted by the magnet will be consistent.
In attraction, the distance is very small, so the break-away energy is very high.
This is inneficient from the very start,. unless your machine is 30 meters tall to counteract the force.
For instance,. whatever height your test was done at, you had to lift that ammount of water.
E = mgh, + E = mgh of the now freed magnet and container, falling distance x
now,.. im sure at some distance... maybe basketball goal? two story house? you will make up for the energy lost due to the magnetic attraction. But generally speaking, thats a losing battle. Theres a reason we use them to hold sh^%& to our refridgerators.
If your goal is to simply measure the break-away force, i would start by mimicing the situation in which that would occur, not physically attached to one another,.