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Author Topic: Electromagnetic Archimed's screw  (Read 2218 times)
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Moreover, only an electric field can move charges when performing work. A magnetic field can only deflect moving charges.

I would add to this that only an electric field can accelerate charges (TPU).  For a long time I was under the misconception that a magnetic field could move and/or accelerate charges but it doesn't.  Logically then, this would leave us with some type of modulated electric field to move charges in an SM TPU which then these moving charges would create a moving magnet field as SM demonstrated.

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a rotating electric field will also cause a compass to rotate if the needle is conductive

   
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I would add to this that only an electric field can accelerate charges (TPU).  For a long time I was under the misconception that a magnetic field could move and/or accelerate charges but it doesn't.  Logically then, this would leave us with some type of modulated electric field to move charges in an SM TPU which then these moving charges would create a moving magnet field as SM demonstrated.

Pm
Since charges that can move are generally electrons that have spin, have a magnetic dipole moment and act like tiny bar magnets, they can be moved by magnetic fields.  A magnetic dipole within a non-uniform magnetic field can endure a linear force and hence an acceleration.  Of particular interest are the conduction electrons in Fe that are partially responsible for its magnetization, I.e.they can become spin-polarized when the Fe ions become magnetically aligned.  IMO there is much that can be done with Fe wire using this electron spin to get anomalous magneto-electric effects.
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Following on from my last post if a Fe rod passes through a toroidal core the electric field from AC current in the toroidal coil will move conduction electrons in the Fe and if that rod has PM's at each end so as to magnetize the rod you will then get some moving magnetization.  Could this be used for making an unusual magnetic motor?

What about a magnetized Fe hoop within a rotating magnetic field?  Can that field create bunching of the conduction electrons with those bunches driven round the hoop at the field rotation rate?  Those bunches will move at much greater speed than drift velocity, can this be used to good effect?  With that hoop passing through four toroidal cores having sequentially phased coil currents you can get similar rotating electron bunches (and hence also bunched electron magnets) creating magnets whirling at enormous speeds well beyond that obtainable mechanically.

So many possibilities!

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Since charges that can move are generally electrons that have spin, have a magnetic dipole moment and act like tiny bar magnets, they can be moved by magnetic fields.  A magnetic dipole within a non-uniform magnetic field can endure a linear force and hence an acceleration...

I agree with that. This only occurs in a non-uniform magnetic field. In all cases, the magnetic field does not work (in the referential of the observer).
 
When the charges rotate (or spin), they undergo the electric field E=VxB due to their speed. It is this electric field, the only one they can feel, that exerts a force. The main effect of this field is to exert a torque by aligning their rotation plane perpendicular to B, and also to move them by the same force F=q.E (where E=VxB) until they are (quickly) balanced by electrostatic forces from coulombian fields. Then no force is exerted, which is why a magnet in the Earth's constant magnetic field cannot move forward, only rotate.
If the field is not uniform, then the static equilibrium cannot be reached, so the charges move.

The key to understanding is to know that in the Lorentz force F=q.VxB, V is the speed of the charge seen by an observer, the one who also observes the B field. But in the proper referential of the charge, V=0, the Lorentz force does not exist, the charge only sees an electric field E, of intensity VxB where V and B are defined in the observer's referential.
If you put yourself in the position of the charge and take its point of view, everything becomes clearer about what it will do.



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a rotating electric field will also cause a compass to rotate if the needle is conductive

You should see the MP4 here: http://exvacuo.free.fr/div/index.php?q=boussole

In this experiment, I had put 2 perpendicular magnets, each powered by two synchronous sine signals of about 1 Hz and out of phase by 90°.
We see that the needle rotates while the field is fixed: we just have the intensity of the field which decreases in front of one magnet while increasing in front of the other, and so on and again, which forces the needle to align with the resultant of the two superposed fields.

At most we can talk of "rotating field" but it's a figure of speech, the field doesn't really rotate.




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a rotating electric field and a rotating magnetic field are two different things
   
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The  circular movement of the compass needle is a  not necessarily a proof of rotation of field at the poles. If you begin to move the frequency lower than 1 Hz, you may observe that the needle just moves between one or the other pole and does not have enough momentum to break free and create full rotation.

However, the compass needle when fully rotating is the rotating magnetic field, since it is a pre-magnetized  dipole in rotation about it's neutral point.

edited for hopefully more clarity, but of course I may be wrong about this as my own experiment may have been faulty in some manner.
« Last Edit: 2019-01-30, 03:29:49 by ion »


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You should see the MP4 here: http://exvacuo.free.fr/div/index.php?q=boussole

In this experiment, I had put 2 perpendicular magnets, each powered by two synchronous sine signals of about 1 Hz and out of phase by 90°.
We see that the needle rotates while the field is fixed: we just have the intensity of the field which decreases in front of one magnet while increasing in front of the other, and so on and again, which forces the needle to align with the resultant of the two superposed fields.

At most we can talk of "rotating field" but it's a figure of speech, the field doesn't really rotate.
Well you agree that the resultant of the two fixed field does rotate.  The resultant of two vectors is itself a vector, so in my mind that is a rotating field.
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If it is the electric field that causes charges (electrons) to move,how exactly dose the homopolar generator work when the magnets are rotated with the copper disk,meaning a non changing uniform field through the disc,and where there is no electric field until current starts to flow through the radius of the disc?.


Brad


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If it is the electric field that causes charges (electrons) to move,how exactly dose the homopolar generator work when the magnets are rotated with the copper disk,meaning a non changing uniform field through the disc,and where there is no electric field until current starts to flow through the radius of the disc?.
The magnetic field from the PM comes from electron orbits or spins, and those charges are moving at near light speed, the spin rates are enormous.  It is the movement of the electrons in the disc relative to those enormous speeds that create the effect.  Rotating the magnet at the low spin rate does little to those relative velocities.  Think of the magnet as simply a container of those enormous spins, rotating the container doesn't really have a significant effect, you still have those enormous spins inside and that is what the disc "sees".
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The magnetic field from the PM comes from electron orbits or spins, and those charges are moving at near light speed, the spin rates are enormous.  It is the movement of the electrons in the disc relative to those enormous speeds that create the effect.  Rotating the magnet at the low spin rate does little to those relative velocities.  Think of the magnet as simply a container of those enormous spins, rotating the container doesn't really have a significant effect, you still have those enormous spins inside and that is what the disc "sees".
Smudge

Yes,and so it matters not whether the magnets are stationary or rotating with the disc.

Now,as the field remains the same,and the effect upon the electrons in the disc remains the same,why dose the electron flow direction change with the rotational direction of the disc when the magnets rotate with the disc?

Changing the polarity of the magnets around leading to a change in electron flow direction through the disc is understandable,but when the magnetic field remains the same,and only the rotational direction of the disc is changed, which causes the electrons to flow through the disc in the opposite direction needs more thought i think?.


Brad


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...when the magnetic field remains the same,and only the rotational direction of the disc is changed, which causes the electrons to flow through the disc in the opposite direction needs more thought i think?.

It is the Lorentz force that acts on electrons. F=q.VxB. If you reverse the angular speed, the linear speed V becomes -V, so F becomes -F: the force is reversed too.


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It is the Lorentz force that acts on electrons. F=q.VxB. If you reverse the angular speed, the linear speed V becomes -V, so F becomes -F: the force is reversed too.

Well no actually.

The disc and magnets may remain stationary,and only the outer brush rotated around the disc's circumference,and a current will still flow through the disc,and a voltage will be produced across the disc.


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I forgot the MHD. I agree, it's really the same principle. I would just like the system to be solid state. In MHD, forces act on the charges of a conductive fluid to provide relative motion.
I'm looking for a way so that the forces on the charges provide a current. We are in 3D: an electric field along X to move electrons back and forth in a current I along X, a transverse magnetic field B along Y, synchronous with I, and which deflects electrons perpendicularly, i. e. along Z, always in the same direction. Therefore, we should detect a current along Z, a kind of full wave rectified current. Even if we don't have the DC component, we should see this double frequency signal. But I never could detect it. Something must be missing or wrong.

A rotating magnetic field created between two perpendicular windings driven in quadrature will accelerate charges, but it will not accelerate them in the directions depicted in the diagram below - which you seem to think. 
Hint: Charges will not be accelerated at all in the middle of the depicted apparatus (along the Y axis and close to it) creating a kind of an "acceleration hole" there.



You have to consider the tangential velocity of the rotating magnetic field line with respect to every charge and then you will get the correct directions of charge acceleration.

The matter is further complicated by the fact that magnetic field lines always form closed loops, and the returning flux is rotating, too (at least in free space - if not guided by a core). 
That returning flux accelerates charges, too ...but in opposite direction. To illustrate this, I have drawn one positive charge in green color which is inside the return flux.

P.S.
Yes, it is true that positive and negative charges will be accelerated by the q.VxB force in  opposite directions, but according to the convention of our scientific jargon these opposite motions of opposite charges constitute current in THE SAME DIRECTION !!!
Conversely, two opposite charges moving IN THE SAME DIRECTION constitute electric current in opposite directions  :o   It is just a matter of jargon - not a matter of direction of motion.   Smudge mentioned that but you seemed to misunderstand him.
« Last Edit: 2019-01-30, 17:13:36 by verpies »
   
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The disc and magnets may remain stationary,and only the outer brush rotated around the disc's circumference,and a current will still flow through the disc,and a voltage will be produced across the disc.
...

When the outer brush rotates around the circumference of the disc, it is exactly the same. It is enough to take into account the electrons in the moving circuit. They cross the magnetic field lines so that F=q.VxB still applies, and F is reversed if V or B changes sign (but not both at the same time).

It's a question of relativity. We have a circuit with two parts that move relative to each other, all bathed in a magnetic field. The effect of one onto the other is reciprocal. We don't know which moves or is at rest because it's just a point of view from the observer, the observer can be attached to one or the other referential.



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The images posted by Verpies look like Marinov's MAGVID.
   
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a rotating electric field and a rotating magnetic field are two different things

Not true, just a question of viewpoint. A magnetic field is an electric field seen by an observer moving with respect to the charges of the field source.

All electromagnetism is perfectly explained by relativity. Relative movements make the coulomb field no longer isotropic, it compresses in the direction of movement because of the lengths contraction (see attached picture), hence the transverse magnetic force which is in fact only the electrical force seen by the moving electron.

See for example the explanation for the experience of Ampère wires in this great course from P Bickerstaff, § 14.8.2 on page 236.

And as already mentioned, a field does not really rotate because it is not a local phenomenon but local scalars related to a distant phenomenon. Its change is only made from the source, in a finite time. A field cannot therefore rotate as if it were a block. If we really want to understand, we must abandon all these easy images.

« Last Edit: 2019-01-30, 18:16:22 by F6FLT »


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Conversely, two opposite charges moving IN THE SAME DIRECTION constitute electric current in opposite directions  :o   
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That's what I said too. Has there been any misunderstanding?
It's the explanation I gave as why it's not possible to detect the current of charges deflected along the z-axis by the Lorentz force, in a dielectrics submitted to both an electric field creating a displacement current in the x-axis and a synchronous magnetic field in the y-axis.
Positive and negative charges move in the same direction, so the net current is null (because each current of charges of opposite sign is in opposite direction).
Perhaps the misunderstanding concerned the word "direction", depending on whether it is applied to charges or to current.

What is very surprising, however, is that the movement of negative electronic clouds is supposed to be of much larger amplitude than that of positive nuclei linked to the dielectric lattice, so the two currents should not cancel each other out.



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The images posted by Verpies look like Marinov's MAGVID.
No, MAGVID has a fifth coil that generates flux parallel to the Y axis.
   

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All electromagnetism is perfectly explained by relativity.
According to Larson, matter moves in all 3D spatial directions and pseudoscalarly in time (a 3D speed of light).
- Diminishing or cancelling one dimension of that motion produces electric effects.
- Diminishing or cancelling two dimensions of that motion produces magnetic effects.

That is why a stationary electric charge (e.g. electron) looks purely electric to a stationary observer and to a moving observer it appears partially as a magnetic dipole. 
If the observer was moving at the speed of light then the charge would appear as a pure magnetic dipole.
   

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It's the explanation I gave as why it's not possible to detect the current of charges deflected along the z-axis by the Lorentz force, in a dielectrics submitted to both an electric field creating a displacement current in the x-axis and a synchronous magnetic field in the y-axis.
These axis designations do not match my diagram.

The Lorentz force accounts for the sign of the charge, so opposite charges will be deflected in opposite directions.
That's why Beta radiation is deflected by a magnet in the opposite direction to the Alpha radiation.



Separating all positive and negative charges in space will create a large voltage potential.  Subsequent relaxation of this potential will result in electric current.

What is very surprising, however, is that the movement of negative electronic clouds is supposed to be of much larger amplitude than that of positive nuclei linked to the dielectric lattice, so the two currents should not cancel each other out.
The proton is 1830 times heavier then electron so there ought to be some differences.

Perhaps the misunderstanding concerned the word "direction", depending on whether it is applied to charges or to current.
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The Lorentz force accounts for the sign of the charge, so opposite charges will be deflected in opposite directions.
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Not in my case. You seem to have forgotten that charges are accelerated by an electric field, so they are accelerated in opposite directions but they are bathed in the same magnetic field.
V being opposite, q being opposite, and B identical, F=q.VxB is the same: the two types of charge move in the same direction. Only the direction of the currents are opposite, likely cause of their undetectability.

Quote
The proton is 1830 times heavier then electron so there ought to be some differences.
The question remains: why can't it be observed?



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A rotating magnetic field created between two perpendicular windings driven in quadrature will accelerate charges, but it will not accelerate them in the directions depicted in the diagram below - which you seem to think. 
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I can't seem to think that for the reason that I've never analyzed this experiment with regard to the issue of charges, but only with regard to the field.

In my answer, I indicated that the magnets increase the field here and reduce it there, and the needle orients itself according to the resultant of the field. It's just to show that a field doesn't really "rotate". We only shape it at a distance by varying the field intensity of each coil, nothing locally rotates, the field of each coil increases and decreases in cooperation and superpose at the position of the compass.


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No, MAGVID has a fifth coil that generates flux parallel to the Y axis.

are you Vencislav?
   
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