Electromagnetic Field

A simple example of a combination of electric and magnetic fields is the field from a single point charge, A demonstration of the effect of an electromagnetic field on an electron beam. The dark circles are the coils of wire of an electromagnet. Current flowing in the wire produces a magnetic field along the axis of the coils which deflects the electron beam in a direction perpendicular it. Photograph by John Howard. National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.

say a proton, traveling through space at a constant speed in a straight line. In this case, the field vectors pointing radially outward would have to be added to the spiral magnetic field lines (circles extend into spirals because an individual charge is moving) to get the total field caused by the charge.