Texas A&M University (TAMU) GEOL 104 Physical Geology Exam 1 Practice Exam

The magnetic field is generated by a geodynamo in the liquid outer core, where molten iron-nickel conducts electricity and moves in complex flows. As heat escapes from the inner core and the planet rotates, convection in this conducting fluid creates electric currents. Those currents generate magnetic fields, and the interaction between the flow and the magnetic field sustains the overall geomagnetic field over time. The solid inner core cannot supply the necessary convective motion, and the silicate mantle is not a good conductor and doesn’t participate in the dynamo. The atmosphere is a gas and also not a conductor large enough to generate the field. So the source is the molten metallic outer core.