thanks all for your comments!
Been thinking a bunch since original post (catalyzed by your helpful comments), and with the add of cracking my physics texts to the right pages (spurned by your comments), I think I see my original question was a bit ill posed. In short, there's no real...
untruncated version of question: As electrons move through a wire, is the direction of the curl of the magnetic field lines observed derivable from an underlying property?
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more detail (only to further clarify my question as useful):
> looking for a mechanistic...