Drawing of a cylindrical ringmagnet with precisely computed magnetic field lines. The magnet consists of a flat cylinder of R/L=2 with a cylindrical hole of radius r/R=1/2 and is homogeneously magnetized  along the cylinder axis. The north-half of the magnet is painted red, whereas the south-half is green. The precise field distribution is obtained by numerical integration. The shape of the field lines is traced with a Runge-Kutta algorithm. The density of field lines corresponds roughly to the field strength, however due to 3D variations of the field, this cannot exactly be fulfilled. The heatmap and contour lines in the background shows the absolute field strength |B|, where blue indicates the strongest field.
Own work
Geek3