Djsquires@aol.com wrote:
>
> Justin,
>
> The levitron works by having opposing like poles facing each other
> to float the rotating one. The gyroscopic forces of rotation stabilize
> the floating one from flipping over. Even then it is really tricky to
> get it going and stable.
>
> The levitron has the magnetic field oriented north to south as up and down.
> So you won't see any changing field lines because the rotation is on-axis
> and there is no variation in field strength as it rotates. You would get
> nothing
> out even if you did have a coil wrapped around it.
> It is necessary to have a field at least varying in field strength or
> changing from north to south to create current flow.
>
> If you did have the field changing it would not be the copper coils
> that would cause the drag and stop rotation.
> It is the back emf generated if you tried to draw current out of the
> coil. This opposes the changing field and couples to the rotating
> magnet and would stop it dead pretty fast. The rotating magnet
> supplies the energy to push electrons through the coil. If any
> are allowed to move by completing a circuit then presto you
> have energy pulled from the rotational energy of the magnet
> and it looks just like air friction or even worse. So the rotation
> would stop. But this is a moot point since the field orientation
> is not right to start with.
>
> Dave Squires