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Re: [Phys-l] induced electric field



I wasn't playing close enough attention as this thread was evolving, but I just took the time to read from the the archives and I am confused and unsettled about what I see, especially with regard to Carl's discussion of the figures at

http://home.minneapolis.edu/~carlsoro/note.htm

I completely agree with Carl's expressed concerns. Subject only to what seems to me the completely uncontroversial interpretation that we are asking about the E field that is induced by the specified time changing B field and are disregarding any other preexisting or background fields, it is clearly (is it not?) the case that the lines of the induced E-field are closed and exhibit considerable symmetry, but are non-circular. Indeed, I would expect them to approach circularity as r -> 0 and as r -> infinity, but to be somewhat "squarish" for radii near L/2.

In any event the calculation of E shown in Note 2 is clearly wrong because it assumes in step 2 a symmetry that does not exist. The same objection applies to Note 3.

It may very well be that I am simply misunderstanding John Denker's points, but I keep reading them as suggesting that the lines will indeed be circular and that there is nothing fundamentally wrong with the derivations that Carl questioned.

John Mallinckrodt
Cal Poly Pomona