This book is an original study aimed at understanding how vacuum magnetic fields change with time. Specifically, it describes the waves that radiate from a sphere when the electric current on its surface is turned on or off, either suddenly, gradually, or periodically. Numerical simulations are an invaluable source of information about this and related subjects, but they are often more difficult to interpret than exact, closed-form solutions that can easily be applied to a variety of situations. Thus, the objective here is to obtain an exact solution of Maxwell’s equations in closed form—something simple, yet rigorous, which can be used as a model for understanding transient magnetic fields in more complicated situations. The work therefore stands as a self-contained solution of Maxwell’s equations for an electric current wrapped around the surface of a sphere. This study assumes a strong background in electromagnetism or a relatedresearch area. Online animations are available for each figure to better illustrate the motions of magnetic field lines.