Hi Horace, >The main reason is that the sum of the forces around a closed circuit is >zero. If a circuit is analysed in two parts, the force on one part (the <snip big elongated explaination>
Actually, my reasoning was simply that forces will arise in inductors carrying a constant current such that the induction of the circuit will increase. That is the case with my example of a permeable member being drawn into a coil, and is the case here where the total inductance of the hairpin loop of wire increases as the armature moves away from the stationary coil. I agree with your analysis, although I'm reluctant to make a blanket statement about the impossibility of a motive force arising in electromagnetic systems. For a long time it was thought that levitating permanent magnets was impossible due to Earnshaw's theorem. It never hurts to do that experiment. K.
