Quote from: alan calverd
"Lines of force" was translated by my old physics teacher as equipotential contoursIn a "bar magnet" magnetic field, the equipotentials would be a a set of nested doughnut-shaped surfaces.
- The Earth's magnetic field can be roughly approximated as a bar magnet
- If electrons orbited the equipotential surface, they would need to circle the entire planet
- This does not align with the observed linear structures in the aurora
- These lines of force seem to follow the path of a small "test compass", from one pole to the other; a path rather than a surface
This is equivalent to the situation with an electric dipole, where the lines of force follow the path of a small test charge. I expect these would cross the equipotential surfaces at right angles.