https://turbowarp.org/930116954?clones=Infinity Mouse moves magnet. "Iron filings" show magnetic field. You can turn off mouse-controlled.
3 major changes: dark mode, you can tell field direction (dot is south), and the dipole is exact for a point (idk the equation for a bar magnet). I can guarantee that the divergence of this field is always zero, thus following gauss’s 2nd law (Δ•B = 0).