I grasp the concept of induction motors - with a rotating magnetic field. A good example is this one: http://upload.wikimedia.org/wikipedia/commons/f/f1/3phase-rmf-noadd-60f-airopt.gif" [Broken] Each outer coil is arranged 120 degrees away from one another and their current is 120 degrees out of phase with respect to their neighbour, and thus the magnetic field vector over time will rotate one way or another. With a magnetic field like this: http://www.physics.sjsu.edu/becker/physics51/images/29_19_Solenoid_Ampere's_law.JPG" (flux into or out of the cross-section of coil) The arrangement that confuses me is this one: http://upload.wikimedia.org/wikipedia/commons/7/7a/RMFpatent.PNG" [Broken] Whereby the solenoids are now not facing towards the center, but instead are actually wrapped around a ring core. I am not entirely clear why these designs work, or even if they are any better? Arrangement 1 is more intuitive to me, in the sence that each coil will produce a magnetic vector in the middle which can be seen to rotate, much like what would be seen if a compass was placed within it. Arrangement 2 however I cannot see a similar picture. Have I overlooked the obivous? Or has detailed calculations shown the two arrangements to work like one another? Thanks for any responses.