In reply to Harry Veeder's message of Thu, 01 Oct 2009 02:20:00 -0400: Hi, [snip] >> The "'positive' in between" is what makes the equations work out. I >> think you >> are having a problem because you expect the net EMF to integrate to >> zero (begin >> point = end point), which it would do if you take the "step" into >> account. Note >> that the EMF does not change monotonically around the complete >> loop. It does >> along the wire (assuming a constant resistance/length ratio), >> however there is >> at least one step when you hit the electrodes. (In the case of a >> battery perhaps >> more accurately one step at each electrode). >> Regards, >> >> Robin van Spaandonk >> >> http://rvanspaa.freehostia.com/Project.html >> > >Explaining the steady current in terms of EMFs does not lead to a >contradiction >so this is not where my problem lies. However, if the steady current is >rigorously explained in terms of electric fields a contradiction seems >to arise.
How is EMF different from "electric field"? IOW why do not have a problem with the former, but you do with the latter? >The steady current requires that the electric field lines >around the loop (i.e. from '-' to '-') form a closed path, otherwise the >current would be fleeting instead of steady. >On the other hand this >contradicts the rule that electric fields cannot form a closed loop when >the B field is not varying as is the case with a *steady* current. ...but individual field lines don't form a closed loop. They end on positive and negative charges in between. That's what the discontinuity is all about that I mentioned in my previous post. It's where the voltage step happens. This is most clearly seen where the separator is a capacitor, and no current flows through the dielectric of the capacitor. All you really have is a "bent" wire connection with two ends. Current flows from one end to the other. This is also true in a battery, but the break isn't as obvious as it's at the atomic level, where electrons and ions separate. Actually there are more like two breaks in a battery, one at each electrode, resulting in two currents, an external electron current, and an internal ion current. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/Project.html
