Regions of constant earth magnetic fields

<div>Approximating the magnetic field surrounding the Earth to be due to that of a dipole, we determine effective regions of constant field. Each region was identified utilizing as basis the outline of a circular trajectory for a charged particle that travels in the equatorial plane. The trajectories were obtained by indicating the center and radius of the circles. It was found that as the distance of the center of the circular trajectory from the Earth is increased, the radius of the trajectory increases.