How to enable a wire to keep rotating

An electrical coil between magnets produces a turning motion.

Opposing forces on a coil between two magnets

Then, the coil rotates to the point where there is no force to rotate the coil.

Equal and opposite forces on a coil between two magnets

Then, if through momentum the coil rotates even further, the forces on the coil would try to move it back in the opposite direction.

Opposing forces can cause the coil to spin

The way to change this is to use a commutator that reverses the direction of the current in the wire coil at point B so that at C the forces are maintained in the same direction.