...perpendicular to its path? OK; let's say you have any charged particle moving perpendicular to a magnetic field; does it describe a gigantic polygon or a perfect circle? I think it's a polygon; the particle absorbs a "quantum of force" from the magnetic field, so to speak, and changes direction. It then travels some distance in a straight line and then the process is repeated. Of course the length of a side is incredibly small and macroscopically it will look like a circle. S.A.