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Author Topic: Magnet Myths and Misconceptions  (Read 605747 times)

SeaMonkey

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Re: Magnet Myths and Misconceptions
« Reply #180 on: October 12, 2014, 03:22:18 AM »
Knowns, unknowns, and beyond.

TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #181 on: October 12, 2014, 03:23:36 AM »
Hey Dave

Ever seen these mono polar motors with the disk mag magnetized to the AA battery and the wire loop that spins around it?  Well this should be similar except im not using 1 wire as they are, but have a rotor with the say N poles of multiple mags very close to the inside windings of a toroid coil. Like Faraday, with current flowing in all the wires the same direction, the rotor should spin with DC applied to the coil.

The other way of doing it would be to have say 2 copper rings, a top and bottom with many thin wires attached from the bottom ring to the top ring, probably as many as possible so there is no spacing between thin wires, then apply dc or pulsing to the top and bottom rings so all the thin wires conduct current in the same direction. This should make the rotor move, all mags with same pole outward.  The first one like I said was simple rough slap together, nowhere near perfect. But the rotor would pop into acceleration just tapping the coil ends with voltage.  I dont know why it would go in either direction at times. could have been spacing of the toroid windings. Inside the say air core toroid, when dc current is applied, the field is oriented in one direction internally, and on the outside of the windings the field is oriented in the opposite direction. So using the toroid model may pose issues as to how it affects the facing field of the magnets once current is applied, due to the field of the mag is inside an outside of the toroid winding before current is applied. But my 2 rings with thin wires vertical from the bottom and top ring eliminates some of the toroidal core area concentration. 

Im planning the build at my shop as we speak. Going with the top and bottom ring with thin wires. Thought of just a short copper tube, 2in is what I have, but I believe there would be too much eddy currents vs thin vertical wires in parallel.  ;)    Plus, in the tube,  if we attach input wires to the top and bottom of the copper tube, would currents be equal and in the same straight up or down direction in all portions of the tube. 

hope to complete today.

Mags
If I am understanding your description properly, I made a device something like that back in 2000 sometime. It was the first AC homopolar generator I encountered. Not super efficient but if you spun it you could clearly see the alternating current it generated.

In your reversible one, are you sure you weren't seeing the Marinov Ball Bearing Motor effect in your bearings and shafts, instead of the homopolar dynamo effect in the disc?

TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #182 on: October 12, 2014, 03:24:18 AM »
This is not good TK-can you not get it all shiped down to you?. Would be awsome to see all your old gear up and running again.
Yes, it is not good. Please check your PMs!

Magluvin

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Re: Magnet Myths and Misconceptions
« Reply #183 on: October 12, 2014, 04:17:09 AM »
If I am understanding your description properly, I made a device something like that back in 2000 sometime. It was the first AC homopolar generator I encountered. Not super efficient but if you spun it you could clearly see the alternating current it generated.

In your reversible one, are you sure you weren't seeing the Marinov Ball Bearing Motor effect in your bearings and shafts, instead of the homopolar dynamo effect in the disc?


Hey T

While looking through all my stuff(good junk ;D ) to build the dual ring, thin wire design, I found the toroid coil and rotor I messed with back then.  The toroid is wound on a pvc board ring, about 4in in dia 1/2in thick and 1/2in deep I wound it tight with 26awg 1 layer all the way around.  The rotor was not as good as I have shown in previous projects, a lil off center. Rotor has 4 1/4in x 1/8in neo disks. Im going to fix that setup to see more what was happening and show.

So the mags of the rotor are all N out, or south, but all the same. Ill have to check if N, but I usually tend to favor N in these cases just to do so. The rotor is mounted inside the toroid so mags are all facing the inside of the coil as it spins.  I imagined that the rotor would spin when dc was applied to the coil. But sometimes the rotor would just jerk into motion, one direction or the other when the source dc was first applied. but no constant spin. I got sidetracked soon and went to another seemingly more important project. 

So all this talk here reminded me of it. So Im putting it back on the table.  The 2 copper rings with thin wires soldered from the top ring to the bottom would be to simulate the inner side of the toroid windings without the complete wraparound of the toroid, so all the wires from top ring to bottom ring have current in the same direction, down or up.  In order for it to be a dc gen, I would say that mags would have to be all the way around the rotor as to affect all the vertical wires equally, or close to equally, otherwise the wires not induced by the mags would dissipate the currents generated output due to all wires in parallel connected to the top and bottom rings.

Sort of if instead of 1 loop of wire from top to bottom of a AA battery with a magnet stuck to the bottom of the battery, we encompass the whole battery/mag combo with many wires. Also, instead of the magnet at the bottom(or top) of the AA battery as we have seen many times, we get the magnet(rotor mags) close to the surface of the spinning wire(my case spinning rotor), instead of working the magnet at a distance as shown in these simple 1 wire loop motors.

Hope that makes sense till I get it together. Working on it tomorrow.

Mags

TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #184 on: October 12, 2014, 05:05:57 AM »
@Mags... ok, I see. Yes, it makes sense. And I have a new little homopolar motor that I'll be showing in a little while myself, nothing new but perhaps a little different than what is normally shown.

Here's something for you to try: But you have to use a saturable-cored toroid for this. Instead of having the rotor and toroid in the same plane, mount the axle of the rotor along a diameter of the toroid, so that they are at right angles. Then you will have the rotor magnets "cogging" at the closest approach to the toroid... and then if you pulse the toroid, it will saturate the core and reduce the rotor magnet attraction for as long as the pulse is on. You can turn this effect into a motor drive. It's the basis of the Steorn Orbo, actually, what I call a CEPM, core effect pulse motor, a very interesting critter, it operates not on repulsion or attraction, but by reducing attraction as the magnet moves away from the "cogging" position.
Good luck, I will be very interested in what you come up with. I'd love to follow along on my own but I can't maintain the necessary tolerances with my present restricted toolkit.

allcanadian

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Re: Magnet Myths and Misconceptions
« Reply #185 on: October 12, 2014, 05:34:09 AM »
I thought I would throw this out to everyone here for consideration.
Now at the beginning of this thread poynt99 suggested that a magnet had no transition point near the field center. I would agree with the notion that a magnet may have an aggregate polarity internally relating to magnetic domains however I would disagree that the external field reflects this line of thought and what is depicted in every textbook.


I found the image below a few years ago at this site: http://physicsworld.com/cws/article/news/2008/apr/08/new-probe-measures-magnetic-fields-inside-solids.


I should also state that I had mapped the magnetic fields of many magnet shapes using an Arduino/labview interface and a purpose built Hall Effect Array many years ago. The image below peaked my curiosity because my hall effect mapping was almost identical to the image I have illegally copied or not found below but that is neither here nor there.


Now you know I just have to ask the question?, which is why most everything I know disagree's with Poynt99's thought's concerning the magnetic field. I'm not pointing fingers or saying anyone is right or wrong here... persay. I'm just saying I find it fascinating that two intelligent and well educated people could come to such different conclusions.


I will let everyone here decide which is obviously a bad choice and I hope Poynt99 chimes in because I believe we all want the same thing despite our differences in opinion. We all want the truth and my truth would seem to be very different than the common consensus. So yes poynt99, you started this thread let's get it on and see where it leads us.


AC

Magluvin

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Re: Magnet Myths and Misconceptions
« Reply #186 on: October 12, 2014, 05:53:22 AM »
@Mags... ok, I see. Yes, it makes sense. And I have a new little homopolar motor that I'll be showing in a little while myself, nothing new but perhaps a little different than what is normally shown.

Here's something for you to try: But you have to use a saturable-cored toroid for this. Instead of having the rotor and toroid in the same plane, mount the axle of the rotor along a diameter of the toroid, so that they are at right angles. Then you will have the rotor magnets "cogging" at the closest approach to the toroid... and then if you pulse the toroid, it will saturate the core and reduce the rotor magnet attraction for as long as the pulse is on. You can turn this effect into a motor drive. It's the basis of the Steorn Orbo, actually, what I call a CEPM, core effect pulse motor, a very interesting critter, it operates not on repulsion or attraction, but by reducing attraction as the magnet moves away from the "cogging" position.
Good luck, I will be very interested in what you come up with. I'd love to follow along on my own but I can't maintain the necessary tolerances with my present restricted toolkit.

Thanks T.   Yes I am familiar with the orbo principle.  ;)   

https://www.youtube.com/watch?v=FrtGzxOKpwQ&list=UUjjcpZL8tkpn4WGkU2y_lPQ

And, maybe you hadnt seen the Orbonbon solid state orbo that I created about 2 months before Naudin had shown his solid state version....  There was a thread back then discussing solidstate orbo possibilities, and this is what I had come up with.

https://www.youtube.com/watch?v=9Ljx1py-BUs&list=UUjjcpZL8tkpn4WGkU2y_lPQ

https://www.youtube.com/watch?v=JYXU_ClBrIA&list=UUjjcpZL8tkpn4WGkU2y_lPQ

It was about the size of a bonbon.  ;)   I gave it a name as you had the Orbette.  ;D

Back to the subject.

What Im thinking is just like Faraday showing 1 wire wants to move when current is applied to it while it is perpendicular to the pole of a magnet, im trying to have a succession of wires next to each other with current flowing in all of them in the same direction but the magnet moves instead. Like I said earlier, the toroid coil may have caused issues with continuous spin due to the concentration of field within the core(plastic, air, etc) vs the field outside the winding in the opposing direction.  I had many thoughts before fiddling, as to the possibility that the field within the toroids core could possibly pull the magnet around, or the field outside the winding would pul the rotor the other way. Get it? :)   But I got strange results. So we will see those results when I straighten out the rotor balance issue and make a vid of that. Then Ill make the vertical wires setup after.  With all the many vertical wires in parallel around the rotor. Ill try current limiting for dc input and pulsing input like used in a very low ohm switching supply primary to eliminate the current limiting.

Im interested to see what you have come up with here also. ;) ;D

Mags


Magluvin

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Re: Magnet Myths and Misconceptions
« Reply #187 on: October 12, 2014, 06:08:30 AM »
I thought I would throw this out to everyone here for consideration.
Now at the beginning of this thread poynt99 suggested that a magnet had no transition point near the field center. I would agree with the notion that a magnet may have an aggregate polarity internally relating to magnetic domains however I would disagree that the external field reflects this line of thought and what is depicted in every textbook.


I found the image below a few years ago at this site: http://physicsworld.com/cws/article/news/2008/apr/08/new-probe-measures-magnetic-fields-inside-solids.


I should also state that I had mapped the magnetic fields of many magnet shapes using an Arduino/labview interface and a purpose built Hall Effect Array many years ago. The image below peaked my curiosity because my hall effect mapping was almost identical to the image I have illegally copied or not found below but that is neither here nor there.


Now you know I just have to ask the question?, which is why most everything I know disagree's with Poynt99's thought's concerning the magnetic field. I'm not pointing fingers or saying anyone is right or wrong here... persay. I'm just saying I find it fascinating that two intelligent and well educated people could come to such different conclusions.


I will let everyone here decide which is obviously a bad choice and I hope Poynt99 chimes in because I believe we all want the same thing despite our differences in opinion. We all want the truth and my truth would seem to be very different than the common consensus. So yes poynt99, you started this thread let's get it on and see where it leads us.


AC

Interesting. ;)   lets say there were lines of force just for example. Also for example sake, N and S have a flow direction, from N(outside the magnet) to south. So in the pic you have shown, the field line exits the N and enters the S.

I can imagine that a N out field line may not just be attracted to only the S pole, but can loop back toward any part of the side of the magnet as if it were a bunch of little magnets(domains) in a row or  train of little magnets. Especially the N field lines exiting the N pole close to the outer ends of the face of the N pole, and the lines from the center of the pole possibly go out the furthest and end up reaching to the S pole side of the mag. Like if we break or cut the magnet in half, each will have the same magnetic orientation as the original. So your pic makes perfect sense to me as compared to just the N field line turning all the way back to just the S pole. 

As with a coil, there just might be the same circumstances. Not sure.

Mags



allcanadian

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Re: Magnet Myths and Misconceptions
« Reply #188 on: October 12, 2014, 06:18:03 AM »
check your pm, personal messages


CANGAS

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Re: Magnet Myths and Misconceptions
« Reply #189 on: October 12, 2014, 08:08:14 AM »
The magnetic field produced by a current-carrying wire is _around_ the wire and you can visualize it as circular loops of field. Polarity is "direction" of the loops, there aren't really "N" and "S" poles to a circular field line or the field itself. The conventional direction of electricity flow is from the positive pole of the source to the negative pole. So if you point your right thumb in this direction along the wire and curl your fingers around the wire, the fingers will be describing the "direction" of the magnetic field around the wire. And you can demonstrate this with a magnetic compass. Believe it or not, for at least 20 years after electricity was being demonstrated in the laboratory, people did not understand that there was a magnetic field associated with current-carrying wires. The story is that it was actually discovered by accident during a classroom demonstration intended to prove that there was NO field around the wire, by Oersted in 1820.
http://en.wikipedia.org/wiki/Hans_Christian_%C3%98rsted#Electromagnetism
Inside the battery, there is a lot of electrochemistry happening and there isn't really a large coherent region where electron current flows. If you had small enough and sensitive enough instruments you could find net magnetic fields inside batteries, but you can demonstrate for yourself that batteries and ordinary magnetic fields don't interact much, by bringing a strong magnet near to a battery that is powering something.
 
"Dose it change from one end to the other-from positive side of the battery to the negative side. Or do we have a monopole field?" Neither one. The field is constant all along the wire and there is no such thing as a "monopole" magnetic field. You can arrange magnets, as in Halbach arrays, so that you only _see_ one polarity outside the bulk structure, but you can be assured that every field line emitted by the thing is in fact a closed loop that has no terminations. DivB=0.

Now it should be plain that if you have a field that is like onion skin shells around the straight wire, if you coil the wire into a solenoidal coil, the "shells" reinforce and add, and you now get a structure that makes "poles", where one end of the solenoid has a lot of field line "directions" coming out, and the other  end has field line "directions" that go in, and they loop completely through and around the whole solenoid. Again, the in and out are conventions, nothing is really flowing along the "lines of flux" of a magnetic field, unless you put it there.


Tink (this is simply a convenient way for me to use less keystrokes to refer to you, if you are in the least offended I will gladly do something else); you are doing OK till you get to the last sentence.

Quote
Again, the in and out are conventions, nothing is really flowing along the "lines of flux" of a magnetic field, unless you put it there.

I explain. Using the lines of flux, or, lines of force, as our mutually agreeable arbitrary model, we do need to visualize something as flowing on the lines. Momentum. The direction of the lines of force is a reliable indicator of the way in which momentum is transferred between one magnetic body and the other body which is being influenced. The imagining of an in and out flow of momentum along field lines is a necessary consequence of the use of "field lines" as an arbitrary visualization aid.


CANGAS 88*

*Hey look at me, I'm like the first rock n roll song Rocket 88.

TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #190 on: October 12, 2014, 08:26:34 AM »
Can you provide some reference for this idea of momentum flowing along magnetic field lines?


Anyhow, here's the small homopolar motor I promised. What is making it turn? What is being pushed against, and how?

http://www.youtube.com/watch?v=wFMq1Cvtg1s

bboj

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Re: Magnet Myths and Misconceptions
« Reply #191 on: October 12, 2014, 08:43:37 AM »
Argh. Charge, motion, field: one thing. One.

What is moving? Charge. What is the smallest chunk of charge? The Unit Charge. Where are these charge chunks? The Negative one is carried by and is inseparable from the electron. The positive one is carried by the proton, and also the positron (the electron's antiparticle). Normally we never actually see those positive charge carrying particles because the proton is buried deep within the nucleus of atoms and the positron is only made in energetic reactions and doesn't stick around very long. So the positive charges we see, like on the top of a positive Van De Graaff machine, are actually "holes"... deficiencies in electrons, places where electrons should be to make everything neutral, but for some reason they aren't there.
OK, now in wires carrying current, you can think of the charge moving fast through the "electron gas" of conduction band electrons, like the momentum moves through a Newton's Balls system, or if it is easier you can think of the electrons themselves flowing along in the wire. Either way, the current (moving charge) is pushed along by the fact that at one end of the wire there is more negative charge than at the other. This of course also means that there is more _positive charge_ at the other end of the wire-- holes where electrons should be.
The reason metals don't flow and collapse from all this electron charge moving around is because there are a bloody _lot_ of electrons, a Coulomb is a huge number of them, and even with currents of kilo or megaAmperes we are still only moving a tiny fraction of the electrons in the wire.
Now, when you move a charge you get an associated magnetic field around it. The field has geometry and strength that is determined by the path and speed of the moving charge. You can think of it like the bow wave ahead of a moving boat. Each moving charge has its tiny "bow wave" of a magnetic field circling around the path of  motion. (But what acts as the "water" in this analogy? That's a very deep question.) But there are many many many charges moving in even the smallest currents. So if you were really tiny and could watch your wire, and a tiny single charge came by, being pushed from behind by MH's "field" or by charge pressure from the charges behind it (same thing) you would see a bump on your field detector as the charge came by. So a DC current--- a single moving charge -- generates a dynamic, changing field at your fixed location as the charge moves past. But there are many many many charges flowing in the tiniest real DC current, so you see what looks like a strong, static field at your measurement point, as the charges flow past so many and so fast your finest instrument can't tell them from a continuous flow of homogeneous fluid.

Now we do know why, or rather how, a boat makes a bow wave. You can't really move through the water without making one and the faster you go the bigger the wave. Charges make magnetic fields as they move relative to the observer. If the observer moves along with the charge... you don't see the magnetic field (because the field just describes how a thing will move and you are already moving that way) but you do see the electric field from the charge which isn't moving with respect to you. Now that duality of electric and magnetic fields, discriminated only by relative motion, is, to me, a grand mystery of the Universe. "Why" does that happen? Well, some people believe that that question can be answered in a meaningful way, and that's why they go out and build particle accelerators and learn complex mathematics. I just look around in awe, myself, and give thanks that things are the way they are. Maybe they could be different... but I doubt it.


eta: The electron's charge cannot be removed from it, but an electron isn't "just" a packet of the Unit Negative charge. It has mass and spin angular momentum as well. What is really weird is that it does not appear to have a "size"... it is considered a point particle, or a probability cloud.


I checked back.
I know what you mean. Thanks

CANGAS

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Re: Magnet Myths and Misconceptions
« Reply #192 on: October 12, 2014, 09:35:11 AM »
Can you provide some reference for this idea of momentum flowing along magnetic field lines?


Anyhow, here's the small homopolar motor I promised. What is making it turn? What is being pushed against, and how?

http://www.youtube.com/watch?v=wFMq1Cvtg1s


Can I provide a reference? If I had a dime for every time I have seen an internet shyster raise this as his defense, his skirt to hide behind.....

Well, you see, actually , Yo hero Tesla did not have a reference to provide all the time, did he?

The best reference for momentum and field lines would be your own physics wisdom and understanding, but you have just been seen to drop the ball and cleverly try to switch the subject so subtlely that nobody has noticed it.

You have evaded the issue momentarily, but I am not lured by any kind of sly trick you might pull out of your cuff. I know a bit about homopolar motors, and it is almost certain that any gimmick you might have to show is one that I have already discovered in my studies.

I do not do Youtube thingys for several reasons. So I have not looked at your Youtube thingy. But, of course, I bow down to the unlimited truth that everything that can be seen on a sleezy Youtube clip MUST be the perfect truth, OK?


CANGAS 89

TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #193 on: October 12, 2014, 09:42:01 AM »
So that would be a "no" then. And now you are back to being the CANGAS we know and love. I was worried about you there for a moment. When you start to agree with me, I need to go back and check my work very carefully.

bboj

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Re: Magnet Myths and Misconceptions
« Reply #194 on: October 12, 2014, 09:59:42 AM »
Can you provide some reference for this idea of momentum flowing along magnetic field lines?


Anyhow, here's the small homopolar motor I promised. What is making it turn? What is being pushed against, and how?

http://www.youtube.com/watch?v=wFMq1Cvtg1s



I think it pushes against the magnetic field induced in the brush.
The brush is not in contact all the time but is pulsing.