What is the significance of the A field in understanding the Marinov Motor?

[Jdo300]

The "A" Field?

Hello All,

A while ago, I had a chance to read this research paper that was trying to explain how the "Marinov Motor" works. In the paper, they explain that it does not use regular induction through magnetic B fields, but instead makes use of the "A" field. I don't remember reading anything about this field in my physics book and was wondering if anyone could point me in the right direction to some good introductory info about it. I heard it has to do with magnetic potential or something. In case you are interested, I also attached the file I was looking over.

Thanks,
Jason O

 

[quasar987]

It is the magnetic vector potential. (One form of one of) Hemlhotz's theorem says that any divergenceless vector field $\vec{B}$ can be written as the curl of of a vector field:

$$\vec{B}=\nabla \times \vec{A}$$

Note that just as the electric potential or the potential energy function in mechanics, the potential vector $\vec{A}$ is not unique but rather for any $\vec{A}$ such that
$\vec{B}=\nabla \times \vec{A}$, $\vec{A}+\nabla\lambda$ where $\lambda$ is any (properly bahaved) scalar function is another vector potential for $\vec{B}$.Additionally (though this information might be superfluous at this point, it is very important), according to (another version of another) Helmhotz theorem, any vector field can be written as a function of its curl and its divergence only. Since we only need that the curl of A be B, we can litrally choose any value we want for the divergence of A.

 

[cesiumfrog]

This paper doesn't seem to refer to what google calls the http://www.electricstuff.co.uk/bbmotor.html" . The latter does not really depend on fields; a current selectively heats and deforms ball bearings so that they (through frictional forces) apply an acceleration.

 

[Jdo300]

This paper doesn't seem to refer to what google calls the http://www.electricstuff.co.uk/bbmotor.html" . The latter does not really depend on fields; a current selectively heats and deforms ball bearings so that they (through frictional forces) apply an acceleration.

That is not the Marinov motor I am looking into. Here is another document referencing it:

http://redshift.vif.com/JournalFiles/Pre2001/V05NO3PDF/v05n3phi.pdf

@quasar987,

Thanks for the info. What physical significance does the A field have? What physical entities does it react with? Or is it just some sort of mathematical abstraction?

Thanks,
Jason O

 

[quasar987]

I quote Feynman:

Nevertheless, the vector potential A (together with the scalar potential V that goes with it) appear to give the most direct description of the physics. This becomes more apparent the more deeply we go into the quantum theory. In the general theory of quantum electrodynamics, one takes the vector ans scalar potentials as the fundamenta quantities in a set of equations that replace the Maxwell equations: E and B are slowly disapearing from the modern expression of physical laws; they are being replaced by A and V.

From lecture 15 chapter 5 of volume 2.