Michel Jullian wrote: > Couldn't a net magnetic field be generated by the varying paths of the > currents through the static track device I suggested, by the same > mechanism you suggested for the BB motor? I don't see how the fact > that one of the races moves in a BB, compared to a fixed circular > track, changes things fundamentally...
OH, I think I (finally!) see your point! Right, it doesn't. My thoughts about the moving track and its relation to the resistance in one direction or the other were muddled; that doesn't make any difference. View it from the frame of reference of the wire, rather than the sliding contacts, and it becomes pretty clear. I think the inductance of the race is the key, and the important think there is that there is one (or just a few) contact point to the outer track, and the point of contact by the ball bearing is moving. Rails or bearing race, should make no difference. > > The nice thing with a circular track is that it is simpler and doesn't > need lubricating, which makes the system easier to study, provided it > works of course. > > Your drift velocity considerations reminded me of a puzzle you > discussed here a few years back, where it was shown how relativistic > effects transformed a purely magnetic force exerted by a current loop > into a purely newtonian force. Could this have some relevance? > > Michel >
