Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] induced electric field



Off-list I was pointed to the following URL:

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

Looking at the 2nd panel (Note 2), I venture to say that circled step 2 does not actually give E because I think E isn't constant along a circle inside a square B-field region. However I could replace E in that step by E-tan-avg (the average value of the component of the E-field tangential - or azimuthal - along the circular path).

I think I can also say that by symmetry E must be purely tangential at certain points along the circle, namely at the 4 points where it intersects the straight diagonal lines and at the 4 points where it intersects similar horizontal and vertical lines, ie. at the 8 compass points N, NW, W, etc.

So all this is a start. Can anyone go on and say more so we can make more progress? -Carl

ps: The question of how to produce a uniform B inside a square region (and zero outside) is a different issue, and also not particularly obvious to me. Just winding a solenoid around a square form presumably won't do the trick. (Because we then have a similar problem to the lack of circular symmetry for Faraday's law - except now for Ampere's law.) I could use a C-shaped magnet with square cross-section and a tiny gap and ignore (probably to my peril) the fringing field.
--
Carl E Mungan, Assoc Prof of Physics 410-293-6680 (O) -3729 (F)
Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-1363
mailto:mungan@usna.edu http://usna.edu/Users/physics/mungan/