Parallel-Plate Capacitor: Fringing Fields & Dielectric Insertion (2D)

This 2D companion is a genuine finite-difference electrostatic solver, not a diagram of one: a Gauss-Seidel/SOR relaxation with a spatially varying permittivity solves ∇·(ε∇V)=0 on a grid for a real parallel-plate capacitor, so the bulging field lines at the plate edges, the live capacitance and stored energy, and the capacitance increase from sliding a dielectric slab into the gap are all read straight off the numerical solution rather than approximated with the idealized C=ε0·εr·A/d formula alone.