Dipole Field LinesThe invisible field around a set of bar magnets, made visible. Each curve is one thread of magnetism looping from a north pole to a south pole; as the magnets slowly turn, the threads snap and rejoin wherever the field briefly cancels to nothing.Michael Faraday drew these “lines of force” with iron filings in the 1830s and insisted they were real, not bookkeeping. Maxwell agreed and gave them algebra: every line traces a constant value of the potential A, and the places the lines cross are the null points that power solar flares when the Sun’s field reconnects.