In lecture last week my professor asked us why the electric arcs formed by the Jacobs Ladder demonstration device rose up into the air. I answered that the magnetic field created by the metal rods exerted an upwards force on the moving charge in the arc. My professor told me this was getting ahead and that the cause had to do with the heating of air particles due to ionization. Was I correct in believing magnetic force has a significant impact on the arc? Or is it negligible? Thanks PF.