Relativistic Rotating Electromagnetic Fields

Figure 5

Speed of the observers of vanishing Poynting vector for the superposition of a Coulomb field and the magnetic field of a point dipole. With respect to the -axis, the left half is approaching while the right half is receding. The white dotted line corresponds to the vanishing of the first electromagnetic invariant; inside it, the speed field for is plotted, while outside for . The field is everywhere of the nonpure type, except on the equatorial plane. Only on the equatorial plane, inside the surface , the electromagnetic field rotates rigidly. Notice that the speed of light is reached only on the light ring (the intersection of the surface and the equatorial plane ), where ; only there the electromagnetic field is of the pure null type; notice that this is in complete agreement with Equation (16).