Looking for help with basic understanding of faraday disk (please explain)

[d3x0r]

I would think a liquid in metal form would not work as well... but it may not matter.


What happens is... electrons are deflected in the magnetic field....


if you have everything stationary, there's of course no motion.  Once you start moving the metal (copper/gallium/etc) then the electrons in the outer orbits can be deflected by the magnetic field.  (moving the magnets does not move the magnetic field)...


without the magnetic field, the electron would be in a 'straight' path... well in a circular but it would be at a specific radius.  When deflected, then the electron moves less straight in that path and is pushed towards the inside or outside (depending on field direction and rotation direction)... as it moves sideways (and start to turn back on its own path), it starts to slow down, and is deflected less... but it has moved... and in a gross fashion electrons can be migrated towards one edge, but there's not much force in this motion...but you can move a lot of electrons at a time for large amount of amperage.


It's kinda like the skimmer paddle on a sewage treatment pond that goes around and gathers scum, and pushes it kinda toward the outside (although the anaology breaks down when reversing rotations etc)....


But; in the case of a metal, when the electron is deflected, it doesn't have to leave its orbital and can drag the rest of its atom with it... remaining kinds neutral, but causing more convections in the liquid maybe

[CANGAS]

Hello, I have spent several days now trying to wrap my head around the whole concept of the unipolar generator. I have developed a fairly clear understanding of many aspects of the device. I could easily build a working model given the materials. However there is a part I do not understand. Nor has any of the untold number of text I have read explained.

What actually occurs in the disk to produce the current? (induction obviously) OK, but what is the disk? (A conductor) OK, but how does the current flow? (in a radial pattern according to lenz law) OK. But why does the current flow? ? ?

(1) The best I can understand is that the disk is a thin section in profile of a very large wire. Is this correct?
(2) Does the current flow in a direct path from center to edge? Does the current move by a centrifugal force?
(3) does the current flow in a spiral pattern? Golden mean or otherwise...
(4) what actually causes the migration of electromechanical force?
(5) can anyone illustrate the flow path of the current in the disk? Does anyone know?
(6) along the flat plane of the disk does a current gradient exist from center to perimeter?
(7) does disk thickness effect current?

Those are questions I have not been able to find answers to on the internet
actually in reading my own questions I think I have determined some of the answers. interestingly enough.
However I will leave them in the hopes that persons with better understanding might impart they're knowledge to me.

Thanks, I know they are very basic questions. But as I stated I was unable to find the answers on the internet.

I too have the Valone book and have found it to be an excellent resource.

Tink has given you very good answers and I will add only a little bit extra. Tink porbly knew these extras too, but just didn't have the time.

(1) The best I can understand is that the disk is a thin section in profile of a very large wire. Is this correct?
(2) Does the current flow in a direct path from center to edge? Does the current move by a centrifugal force?
(3) does the current flow in a spiral pattern? Golden mean or otherwise...
(4) what actually causes the migration of electromechanical force?
(5) can anyone illustrate the flow path of the current in the disk? Does anyone know?
(6) along the flat plane of the disk does a current gradient exist from center to perimeter?
(7) does disk thickness effect current?

(2)......Every diagram or written description prepared by an expert in the field, including those coming from the hand of Tesla himself, which I have seen, have shown the path of the current to be a straight line between center and location of the pick-up on the perimeter. One of Tesla's drawings pointed out that eddy currents may, however, go round the back of the barn. Somewhere, I cannot possibly remember where, I have read an analysis of the effect of centrifugal force in a Faraday: the math shows there to be a quite small perturbation of the electrons in the electron gas, but, it is so small as to be worthy of neglecting it. Bear in mind that the actual velocity of individual electrons in the electron gas is about 1% of the velocity of light, so, the disk would have to be spinning pretty damn fast to produce a resultant that would be noticeable in the path of the electron. Although, if you wish to ponder drift velocity of current electrons, which in many everyday cases, such as the electric system of your car, is vaguely like maybe one foot per hour, then it could make sense, but there is the opposite problem; the disk would have to spin very, very, slow so the velocity resultant would be recognizable. I am not sure why Tesla recommended spiral shaped segments making up the disk. Is it possible that he understood more about the Faraday than me??

(3).....Hmmmm, maybe an eddy current current might go in a spiral path.

(4).....It has been helpful to me to visualize the interaction of an free electron in the electron gas within the disk, with a field line. 

(5).....Somewhere, don't remember exactly where, I have seen a diagram drawn by Tesla himself, perhaps, illustrating the path as he envisioned it to be.

(7).....Cross-section size of the conductor always has a direct effect on the resistance encountered by the current.

[8]....huh?! There ain't no 8, boss! I know, I'm just bein' cute. REMEMBER that the drift velocity movement of current electrons is ANTIPARALLEL, in the OPPOSITE DIRECTION, to the direction of movement of CONVENTIONAL CURRENT. You may give thanks to Uncle Ben for all the confusion. 


The study of the Faraday Disk is fascinating. Welcome on board!


CANGAS 141

[DreamThinkBuild]

Hi d3x0r,

Thank you for the reply. I see what your saying that there is a boundary effect between the changes in the velocity of the fluid as it travels outwards. Hmm.

I wonder if this could be changed to a liquid dielectric (ie: propylene glycol) the charge would then be parallel to the axis. Then use top and bottom concentric rings to tap off the charge. A homo-polar ultracap?

I'll move this if its going off topic.

[pomodoro]

An interesting experiment I did  with the setup as a motor is to replace the outside brush with a conducting solution.

With the magnet and center shaft vertical, like a pendulum, and kept stationary.
The magnet is made to dip in the liquid.

When power is applied to the liquid and central wire, the magnet wants to spin, but if kept stationary, the liquid begins to rotate around the magnet!