Beaming effect for a relativistic electron emitting synchrotron radiation. If the magnetic lines of force are perpendicular to the paper, an electron moving left to right will be accelerated to its right, due to the Lorentz force, resulting in the curved trajectory shown in dashes. In the first panel, a non-relativistic electron emits photons that propagate in two equal lobes away from the particle. In the second panel, a relativistic electron emits most of the power into the leading lobe. Image courtesy of Chris Flynn.