Do Magnetic Flux Lines Ever Intersect?

There are some great physics applets available to assist in visualizing and understanding interactions of the kind of which the OP has inquired.

http://www.falstad.com/emwave2/

This one is interactive and very easy to use.

BBB.....

Thank you very much for that link to electrodynamics. I think it will take time for me to try out different versions.

Many times I thought "A diamond is used to cut another diamond" and from that started an idea to "Use one magnet to stop another magnetic field".

I also going to look at behavior of (soft or permanent) magnetic fluids under another magnetic fields etc etc.

different guest:

Maybe invest some time understanding vector addition and representation - possibly using basic (static) mechanics. In mechanics, you will find that the strength of a vector is usually represented by its length, but gravity can quite reasonably be represented by field lines similar to those of electrostatics. Once you start to add gravity fields using algebra and numbers rather than pictures you will soon see that the effects you desire cannot be caused in the abstract way you are looking for. The problem here lies mainly in trying to make a representation stand for something it does not.

Which rather brings me to your tag line "To succeed, you have to believe in something with such a passion that it becomes a reality." The thing you believe in does at least have to be possible - unless you redefine success (many do). Must dash, I'm off to breakfast with the white queen...

as I understand it, the right hand rule rules... so the weaker field is displaced, and not cut (intersected) in a direction that complies with the rule. We are swimming in oceans of magnetic fields from the earth, sun, moon, and universe.. Like gravity, the fields approach zero, but are never actually zero I think.. so in that regard, your first magnet is also intersecting some other field.. your compass is a small magnet orienting to north Because the fields don't intersect. (evidence?) (I think it more accurate to say "Cut" than interesect)

Chris

Flux lines are merely a construct to help us visualize the field. The field does not exist as individual lines. The field is more of a vector space, the intensity of the field is the some of the vector spaces

Cheers

Martin

I'm no physicist, but when I studied electrical fundamentals, they told me that Nothing can cut a magnetic line of force.. on this basis, motors work, as the magnetic lines from the stator are not cut by the lines from the rotor, but repulsed due to the inability to cut each other...? I've heard that the 'lines' are a graphic representation.. but really are they??

cheers,

Chris

It would seem like they cancel each other out - this is how we reduce inductance in bus plates, and I think this is how twisted pairs work.

Ed Galicki

San Diego, Ca.

Hi Ed,

maybe I'm misreading the OP's question... but otherwise I would have to disagree.. I think that they displace based on the 'rule'.

cheers,

Chris

No, bus plates are placed at right angles to prevent mutual induction, not to cancel anything out. Twisted pairs increase common mode rejection by evening out the induced currents on each line

Cheers

Martin

Dear drobertson,

so what you are saying is that all the rest of the subatomic world is quantized... except magnetism? and there, we only pretend it is quantized?? What is the evidence that magnetic fields are Not quantized into lines?

Cheers,

Chris

Electromagnetic force is an effect, not a particle. I am sure that physicists who are much smarted than I am have integrated electromagnetic force into quantum theory, but the concept of lines of force is still wrong under that model. I have no problem with the use of field lines to show the intensity of a magnetic field vector in a way that is similar to contour lines on a map. It helps to visualize what is happening by using the lines, but just like the real world that is represented by the map isn't made of lines on the ground, neither is electromagnetic force made of lines in the air. Any description of "cutting through magnetic field lines" is very inaccurate and needs to be corrected.

Hope this helps a bit.

-Doug

I would think that if a magnetic field was quantized into "lines", one would have a constant variation in the field strength. High at a line, low between lines. But in reality, the force field is homogenous and varies in strength slowly across the field.

Magnetism is of course quantised. But this is not necessarily a matter of localisation (if anything it would give uncertainty of position, so its effect would be the reverse of the field line representation). It is simply that the magnitude of any event is quantized. But the other thing to realise is that at "DC" the magnitude of the quantization would be zero*. It's only at non-zero frequency that the size of the quantum is significant (E=hν).

*Of course, DC doesn't really exist - this just means that the quantum can be arbitrarily small if you are patient enough (see Heisenberg).

Basically from the contributions made by so many I understand that flux lines do not intersect. Mr drobertson has summed up towards the end by brining up the issue of nearness and strength of the magnetic lines of force etc.

For some of those who state that the magnetic flux lines are only concepts - I wish to state that - we need a visual medium to understand. Let us not forget that magnetic flux lines influence (visual or non does not matter).

Now let me mention why I raised this issue. I have worked in electronic energy meters filed. There has been a need to find ways of warding off influence of tampering external magnetic field. This is a global need. As we all know there are no magnetic mono-poles. Hence it is extremely difficult to come up with magnetic shields - thick or thin.

Hence this simpel idea of using one magnetic field placed permanently in a plain to block tampering magnetic (DC or AC) field penetrating into undesirable area / enclosure. This can be extended to larger areas (call it mesh) also by having grids of permanent magnets.

Magnetic flux lines do not intersect simply because they are force fields applied on a ferronmagnetic particles.

When ever there is more than one force applied (think about the mechanical force), the resultant force at that point is the vector sum of individual forces.

In the same way, the imaginary flux lines (like any other imaginery force lines) will converge (tangentially) and redirect themselves based on the nett force on that point.

The Shielding against magnetic - stationary/dynamic is not possible by another magnet since one can bring in a magnetic field stronger than what you have put.

Only way is to use natural lays (usual shields- eddy is used to cancel out the imposed field- dynamic) , superconductors are next step. However if you put a stationary field to then except superconductor all other will fail, unless your screen to rotates at the speed of the disk.

Electronic meters are hoewver not supposed to be affected by this or are they?

I hope the responders to the thread are now able understand what I am looking for. Kindly see another response above - where two magnets N &S which may be less powerful, but are so closely placed that a powerful magnetic filed fro a larger distance may have same effect. Let us not keep arguing too much about how much weak, how much powerful, how much distance etc etc. The external magnetic field can be diverted (vector addition) and its effect can be minimized or nullified.

Basically let us see how to take advantage of this simple statement - magnetic lines of force can never intersect. (whether they exist, seen , not seen etc is least of the point). Look at end application. Superconductors etc etc are there - but at what cost, at what temperature etc etc.

You mention some speed of rotation !!! A permanent magnetic field will deflect an in coming AC filed of any frequency- direction of deflection will change- but in any case it can never penetrate a permanent magnetic invisible screen !!! Electronic meters are affected (when current sensing is by CT). Recently some people told me even shunt performance is affected.

Look at the vector diagram.

You have one field made of the PM and the other disruptive field, let me say the one I am imposing to tamper the meter.

At any point , the field strength and direction will be the vector sum of the two fields.

If my disruptive field is too strong, the PM field will be simply punctured by it, and most likely the PM will lose its magnetism/ its magnetism will be aligned along the new magnetic field. is not that exactly what happens when you put a ferro magnet or even a magnet inside a strong (magnetically) solinoid?

The only way to negate is the usage of eddies- which simply by the effect of inductance will try to oppose any imposed field.

The problem is when it is a DC field. Now sooner or later (in non-superconductor) the resistance will wane and the sheild will shield no more.

Effectively what you need is a device like the antinoise - which will sense the external field (noise) and create one at 180 degrees out of phase with it.

No. Think of the flux lines as little arrows pointing in the direction of the magnetic field. If they intersected, then at some point the magnetic field would be in two different directions.

Let me simplify and try explain this in a layman's language: As we all know the magnetic field is the force originated from magnetic poles. The field is like an ever expanding circle with the pole at its center and magnetic force coming out radially in all directions. In your case the two poles are at a distance from each other and they do interfere with each other. Now, the magnetic effect on any point in these two fields is merely a consolidation of these two fields and whichever is the nearer pole, will exert the net force. The flux, as you say, do not cut each other, but can nullify each other and the net effect at a point equidistant from these two poles will be zero.

The easiest way to understand "field lines" whether magnetic or electrical is to start from topographic maps in geography. If you draw a map with contour lines representing the local heights, the contours will be approximately equivalent to the so-called field lines. However, the rules that govern electric and magnetic fields are slightly different from those governing geography: in geography you could have an overhang, which would theoretically allow multiple height values at a single point - so the representational lines could cross; in classical electricity and magnetism there is no equivalent of an overhang, so the lines cannot cross.

In QM representations, nothing has a definite value until after the event; if you want field lines, they would be blurred. Some might say that the "potentials" become multivalued during a quantum transition, but this has no predictive value, so I believe it should be treated as meaningless

Have you considered doing an experiment with two horse shoe magnets of similar strength and some iron filings to see what happens?

In any infinitesimal volume range the vectors of any magnetic or electric field are parallel

Jaime

I think many trying to argue about geography, topolgy, imaginary line etc etc - must have read and understood that right in the beginning someone has mentioned Flemings Right hand rule.

I too came to the conclusion that two magnetic lines can never intersect based on Flemings left hand and right hand rules. The nature is such that there must be balance- no stresses. Hence when a conductor carrying current has a magnetic field around it, and an external magnetic filed is brought close to it, the conductor experience force- so that it tries to get into a position where the magnetic lines of current and external lines do not oppose, but are in same direction.

Hence Flemings Left hand rule of right hand rule to be applied here also. Instead of a magnetic field generated by current, I am keeping a permanent magnet which is firmly anchored as a gate/ barrier - to prevent entry of any other lines of force past the barrier. thus it cats as a low cost magnetic shield.

Using one magnetic field to prevent entry of another field (AC or DC) !!

"Let your imagination drive your vision." -- Susan Clampitt

To continue one of the posters idea I would like to point to a possibility of tampering a traditional energy meter. The electronic version can not easily be tampered, because they do not use electromechanical effects. But those meters with the rotating dish might be tampered by introducing an external magnetic field into the the gap of the magnetic core where the dish is rotating. However, this magnetic field must be strong enough to exceed the magnetic field strength in the gap. Since it is an AC meter, the external field must be AC too with the exactly same frequency and a stable and possibly adjustable phase angle with respect to the magnetic field in the gap. Provided all these measures it would be possible to e.g. spin the disc backwards and lower the counter of kWh. Very likely will one need a multiple of energy of the maximum amount of what the household may consume :-)

Some thoughts regarding magnetic flux: lines of flux are used to indicate the direction of the magnetic flux on e.g. paper or 2D media in general. If you use your universal 3D magnetic flux meter you will get for any point in the space which is exposed with magnetic field a reading with e.g. field strength in any of the three axes, X, Y and Z as well as frequency and phase shift. Upon moving the probe within the space the values will change but the will not jump to zero. The field strength reading will always be continuous, such that one could draw a flux lines at any arbitrary point in space.

Reffering to magnetic field generated by el. current , please visit my experiment

at http://commons.wikimwdia.org/wiki/File:ExperimentTORIS.JPG

thanks for attention.

I got a message web page not found. Kindly check up. I am keen to see.

try serching with google ,typing

File:ExperimentTORIS.JPG

or send to me your E-mail adress .

I am not an accademician. I did visit the web site you refred to. I could not correlate this experiement with what I am looking for.

There is doubt that two magnetic flux lines (imaginary, no-visible, conceptual) do not cross. PERIOD. Flemings left hand and righ hand rules support it. Rest is accedemic discussion going on now.

Kindly read my postings. Though I kept the original posting a little vague, look at posting at 20. I am looking for an industrial application.

Thanks for vist on my experiment "TORIS 1982" that demostrate , through measurement , an difference .....bethwen theorie and reality .

Others, using superconducting magnets, have performed nulling experiments on this sort of issue that have sub-ppm resolution; this was mainly to confirm constructional accuracy. These workers have so far found no discrepancy between theory and practice. You should therefore be confident that, carefully implemented and analysed, any "difference between theory and reality" with your toroid will be equal to the level of precision (both of model and of construction) at which you are able to work.

Let us look at some rather basic levels of modeling:

The crudest model pretends the toroid is a skin of current with perfect rotational symmetry around the axis of the toroid. This won't show anything, of course.
The next level for a simple winding would include a current skin that encloses the axis, showing that a unidirectional winding will indeed generate an axial magnetic field. This gives the initial information that the series winding with reverse spiral (the one I think you implement) is needed. At this point we need extreme care in the implementation.
Now, as you appear to have a reverse spiral wound around the outside of the first, we need to correctly locate the current skins that enclose the axis. With your arrangement as drawn*, the current skins for each winding will approximate a pair of planes that are parallel to the flat surfaces of the reel; the critical feature here is that the pair representing the reverse set of winding is axially separated by more than the first. This means that, at this level of approximation the axial field due to the first winding will be greater than the axial field due to the first winding. This is for coils that are perfectly constructed to your drawing. The overwinding is also likely to induce differences between the systematic bending of the inner and the outer coils - and the distance between the axis of the toroid and the circumferential contributors to the current is also important, as quite small departures (either in the orientation of the axial sections or the straightness of the near-radial sections) could have significant effects that would exceed what would be seen with ideal construction. Similarly, the BC sensor will need to be accurately placed, and the radial winding leavings both the BC sensor and the toroid will need to have near-zero area in all relevant planes (you probably need small-diameter coax, and the ability to check two orientations of coil without disturbing the location). That said, any noticeable difference between the coupling of my simplified model and your measurtements would merely represent a difference between design and construction - which is by no means a "difference between theory and practice" (at least in the sense you imply).

N.B. if you wish anyone to take this seriously, you need to indicate clearly the dimensions, constructional accuracy, number of turns, locations and design of pick-off wiring, drive currents, and measurement frequency of your system, together with the Voltage you have measured from the pick-up coil (28 years should be long enough to get this together - but maybe once you have done this you will see for yourself where the "discrepancy" might be coming from).

Fyz

*Windings appear either to be axial or to be guided by the plane surfaces of the bobbin

Erratum:

The sentence:
"This means that, at this level of approximation the axial field due to the first winding will be greater than the axial field due to the first winding"
should read
"This means that, even at this level of approximation, the axial field (as seen at your sensor coil) that is due to the first winding will be greater than the axial field due to the reverse winding"

the correct link to Experiment TORIS 1982 :

http://commons.wikimwdia.org/wiki/File:ExperimentTORIS.JPG

Inspired by Oersted''s affirmation in 1820-1820 on "spiral shape" of "conflictus electrici"( now magnetic field) I have realized an experiment with toroidal winings :

http://commons.wikimedia.org/wiki/File:ExperimentTORIS.JPG

Do magnets have a frequency?If so, what is the frequency of the Earth's magnetic field?

Do magnets ever lose their magnetism if their forces are applied or utilized? Do the permanent magnets in a motor ever wear out or lose their force of flux? A permanent magnet works in conjunction with an electromagnet to create a force to turn the motor, right? In that sense isn't a permanent magnet sort of like a fuel cell with stored potential energy?

I too wanted to understand this phenomena better. Kindly post it separately in another thread.

My response has appeared as though from a guest - as I seem to have closed the login window first !

I'm confused. I posted #27. I'm not sure how #30 answers #29 which is in regard to my question #27.

I'm responding a little late, but hope I can shed some light.

In effect....yes. The magnetic field strength from two sources are additive. Depending on the polarity, they can therefore also have a cancelling effect.

To protect or block a magnetic field, in my opinion and experience, the best approach would be to construct a shield with material like mu metals (and a provide better understanding of what you are protecting). I can understand why you would not (or could not) provide that in an open forum.