Faraday paradox revisited,magnetic field rotation question.

[guest1289]

    Actually,  I have to admit that I still think that  'Technically'  the  'Disk-Permanent-Magnet' in my question is supposed to be rotated by the electromagnetic-field from the wire.

   I especially think so,  if you place the wire near the outer-rim of the  'Disk-Permanent-Magnet' , like in the  diagram  below .

   Because,  thats exactly how the  homopolar-motor works  :

       https://en.wikipedia.org/wiki/Homopolar_motor
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  PolaczekCebulaczek

   The  'Faraday-Disk-Generator'( homoplolar-generator ) should also function as a  motor,  if you run DC-current through the metal-disk( a non-magnet ) .

     https://en.wikipedia.org/wiki/Homopolar_generator

     Your Question :
      - So,  what happens when you increase or decrease the DC-current when using the 'Faraday-Disk-Generator' as a  motor,  does the speed change  ?
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    The electric-field ( electrostatic charge ),  and magnetism,  are almost the same thing, intertwined,   this was unified in einstein's theory of relativity( or one of his main theories ).
    The rotating/moving electron's electric-field is basically what the magnetic field is made of,  in a magnet of course the atoms?/electrons? are all aligned in one direction.
     I'm sure there must be all sorts of opposing theories,  because there's no proof for any theory regarding what the magnetic-field is made of.

[lumen]

I see it like this:
An electron that changes a shell level in a gas emits a short magnetic pulse that is in the light spectrum. So an electron that is moving at a constant rate will generate a constant magnetic field.

The moving electron creates the magnetic field but a moving magnetic field does not create an electron but only causes it to move and create a counter magnetic field.

It all seems to come when energy moves in space. So then if mass moves in space, what does it cause?

[allcanadian]

Nobody seems to be making any headway so I will give you the solution.


We have three scenario's.


1)only the conductive disk rotates relative to a stationary magnet... a voltage is induced.


2)the conductive disk and magnet rotate together...a voltage is induced.


3)only the magnet rotates... no voltage is induced.


Scenario 2 is unique in that we do not need a conductive disk if the magnet itself is made of conductive material. A magnet rotating on axis will induce an Emf or voltage from center to perimeter or vice versa thus a separate conductive disk is not actually needed.


Let's look at the experiments, in scenario 2 when the conductive disk and magnet rotate together we cannot induce an emf unless the field is stationary. There must be relative motion to induce an emf according to Faraday's Law and if the field rotates with the magnet then there is no relative motion between the disk and the magnet and it's field. Therefore the field must be stationary as the magnet and disk rotate together to induce an emf.


As well in scenario 3 when only the magnet rotates relative to a stationary disk we see no induced emf in the disk. If the magnetic field did rotate with the magnet we should see an emf in the disk however we do not proving the magnetic field is not rotating but stationary. This is Faraday's Law...it does not matter how the change occurs (a magnetic field change) only that it does. Obviously the external field did not change in the disk otherwise we would see an emf. Think about that for a moment... the magnet rotates but there there is no induced emf in the stationary disk as we thought there should be but there is an induced emf present. Do you know where?, unfortunately I'm guessing no. I already told everyone that scenario 2 is unique in that the magnet in itself will induce and emf if it is made of conductive material so yes there is an induced emf just not in the stationary disk but in the magnet.


At which point we may address the confusion some have with these scenario's. Some have argued that in scenario 2 when both the disk and magnet rotate together the induced emf in the disk should generate eddy currents and drag. They imagine a scenario where the stationary field of the rotating magnet induces the rotating disk which then generates eddy currents in the disk acting on the stationary field. The scenario where an apparatus "acts on itself" which is not the case here. The stationary field is uniform and when the disk rotates it produces a uniform radially acting emf from let's say center to perimeter. Thus the uniform radial emf cannot loop back on itself to produce an eddy current because the direction of the emf is always from center to perimeter at all points of the disk. This is generally the reason why this seems so confusing to most because they are looking for something which does not actually exist... there are no eddy currents and no drag because the emf is uniform and acts radially outward or inward at all points of the disk. The Lorentz Force dictates that if the field change is uniform and it is then in this case the induced radial emf must be uniform and it is.


Note when only a magnet with no disk rotates there is still an emf induced in the magnet. However there is also no drag associated with the rotation of the magnet relative to the stationary field because no eddy currents or current loops are generated within the magnet. The emf is uniform and can only act radially from center to perimeter or vice versa with no reversal to generate eddy currents or current loops hence all confusion.


Next we have scenario 3 where only the magnet rotates and we see no induced emf in the stationary disk. In my opinion this is where logic and reason should have entered the equation however for reasons I cannot explain it did not. If in fact the magnetic field was rotating with the magnet then by Faraday's Law we must see an induced emf in the stationary disk and yet we do not. Pretty simple concept... Faraday's Law states if the magnetic field has any relative motion there is an induced emf.

In my opinion the worst case scenario is that somehow for reasons completely unknown to me some believe the magnetic field has induced a massive emf in the external wires closing the circuit. However they forgot a few simple laws found in every high school textbook. One is the inverse square law and in a homopolar generator with two magnets and a conductive disk in between there is basically no external field thus no appreciable field to cut or more so induce any external conductors. Again we have a major flaw in logic and reason of epic proportions. If there is no external field to induce the external conductors then how exactly could any emf be induced?... obviously this theory it is completely absurd.


This is basic grade school science, Faraday's Law, and then someone introduced a variable which caused everyone to lose their mind... I'm not sure what the problem is here.


AC

[lumen]

@AC
How many different conditions are there?

Did you include rotating only the external conductor with magnet and disk stationary?
Did you include rotating the disk and external conductor with only the magnet stationary?

What are the results?

[guest1289]

allcanadian
   I don't even know if  'my own'  question belongs in this thread.
       I will be re-reading that last post a few times,  to try and understand it all .
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   In accordance with what PolaczekCebulaczek and citfta said,  the DC-Motor in the animated-diagram below,  should not rotate( with or without commutation ),   if the 2-magnets were replaced with 1-ring-magnet

https://en.wikipedia.org/wiki/File:Ejs_Open_Source_Direct_Current_Electrical_Motor_Model_Java_Applet_(_DC_Motor_)_80_degree_split_ring.gif   

   (  NOTE : In this animated-diagram,  I can only see that the  electromagnetic-fields  from the relevant sections of the rotating-wire,  are actually  'Parallel'   to the  Magnetic-Field occurring between the 2-permanent-magnets,   instead of being   'Perpendicular'   ? ,     that has given me more possibilities for my own question    )

   SO,   'if'   that DC-Motor would rotate inside of a  ring-magnet,  then,  the ring-magnet could be the rotating-component in that DC-Motor,  which means that the  Disk-Magnet  in  'my-own' question should rotate.
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  The thing I can't understand is when current is passed through 'Permanent-magnets',  which seems to be done in some homopolar-motors,  unless I'm wrong.
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   The 2-scenarios in the  diagram below  -  Is it true that no rotation will occur in both scenarios,  if no current is allowed to flow through the permanent-magnets in that Faraday-apparatus(  if the permanent magnets were sealed in glass/plastic ) .

    https://en.wikipedia.org/wiki/File:Faraday_magnetic_rotation.jpg
       
    I'm sure that rotation would still occur,  but I assume I'm wrong