Motivation
The point was to prove that an electric coil can be used instead of a permanent magnet to produce exactly the same effect.
Orientation of the magnetic field
The magnetic field of the electric coil corresponds to the magnetic field with the permanent magnets set up, where the magnets on the other side of the copper disc, facing in opposite directions.
![](https://unipolarmotor.erwin-research.com/wp-content/uploads/2024/06/electric-coil-magnetic-orientation-1024x576.jpg)
The magnetic field is described by a simple torus field.
Direction of rotation
An interesting observation is that the direction of rotation does not depend on the direction of the current. This behavior can also serve as a proof that it is the same effect as caused by a permanent magnet, because this can only be explained if the current from the axis to the coil has a part in the force of the rotation.
![](https://unipolarmotor.erwin-research.com/wp-content/uploads/2024/06/current-flow-left-1024x576.jpg)
Here the current flows from the axle to the coil, the magnet field (B) is caused by the current which flows from the inner winding to the outer one.
![](https://unipolarmotor.erwin-research.com/wp-content/uploads/2024/06/current-flow-right-1024x576.jpg)
Here the current flows from the coil to the axle, the magnet field (B) is also changed because the current in the coil flows from the outer winding to the inner one.