Electronic – Electrical Machines based on Electric Fields

"Vehicle detection loops, called inductive-loop traffic detectors" are one pretty common method. A groove is cut in the pavement, wire is layed in the groove, the groove is filled in with a sealant, and the wires go to a processor which makes the wire act like a metal detector - the vehicle interacts with the e-mag field, and the processor detects that.

Are you allowed to sawcut the area in question? If not, then a different method should be selected. Maybe just tubes across the road as one finds leading into or out of a town so the local municipality can count how many cars are using a road. I imagine they just detect change in air pressure as cars drive over the tubes.

Well, you cannot deny there is a force between rotor and stator. It's exactly the same force between two fixed permanent magnets. They are fixed but if let loose would collide with each other. This can't happen in a motor because the rotor is constrained radially. Does torque also exist? Yes it does - to overcome windage and friction exhibited by the rotor. That's the no load scenario and clearly an increase in torque exists when mechanical load is applied.

It's also interesting to note that if the rotor was mechanically lossless, the rotating mag field would be physically coincident with the exact centre of the rotor pole aligned with it. As load is applied there becomes a misalignment that inevitably produces a hight force between rotor and rotating field. Maybe this is a more satisfactory explanation?