The Cause of the Earth's Magnetic Field

If one wants to understand the cause of the earth’s magnetic field one could go into the calculus version of the explanation or one could go back to very fundamental thinking in electricity and magnetism and this I choose to do. I will also limit my explanation to direct currents, which is the concept that the current flows only in one direction at a steady rate. First lets think of electrons flowing through a wire, then the explanation of the magnetic field produced around the wire can be understood by the left-hand rule. This rule states that if the thumb points in the direction of the motion of the electrons when the left hand is placed over the wire, the fingers will point in the direction that a north unit pole would travel if free to move. This is equivalent to saying that if a very sensitive compass were placed where the fingers were, then the north-seeking pole would point in the direction that the fingers were pointing and this would be towards a South Magnetic Pole.

Now lets apply this rule to the earth. If we are on the magnetic equator and our left-hand thumb points eastward, then the fingers would point in the direction that a north-seeking pole would travel if free to travel. The north-seeking pole would travel towards a South Magnetic Pole. This then indicates that a South Magnetic Pole is located at the North Geographic Pole.

We can extend this thinking to positive charges that are flowing eastward which requires us to apply the right hand rule for positive charges flowing eastward. If we are on the magnetic equator and our right thumb points eastward then our fingers on the right hand would point in the direction that a north unit pole would travel if free to travel. This tells us that a South Magnetic Pole is located at the South Geographic Pole. But this can’t be because we just used the left-hand rule and found that there was a South Magnetic Pole at the North Geographic Pole. If there were a magnetic reversal of the earth’s magnetic field then the latter case would be correct.

Again if we stand on the earth’s magnetic equator and let both thumbs point eastward simultaneously, then our fingers on one hand would be in opposition to the fingers on the other hand. This requires an explanation. There are two types of charges in the earth and they are both traveling eastward and both types of fields can be produced but not at the same time. At the present time the left-hand rule predominates therefore the field is due to electrons traveling eastward in the earth. If there were a reversal then the right hand rule would predominate indicating that the reversed field is due to positive charges traveling eastward. At the center of the earth the magnetic lines of force cannot go in both directions simultaneously. When the earth’s magnetic field is normal, the lines of force due to positive charges are cancelled out, however if the earth’s field reversed then the lines of force due to electrons are cancelled out.

When we measure the earth’s magnetic field on the surface of the earth we are measuring the difference between both types of magnetism and at the present time this field is due to electrons traveling eastward in the earth. If there were a reversal then we would be measuring the field due to positive charges traveling eastward in the earth. Both types of charges are in the center of the earth and traveling eastward.

Now about the center of the earth, the temperature is estimated to be about
6000 degrees and at this temperature there will be ionization taking place.
This means that electrons are being separated from the atom. Where do the
electrons go? At the temperature stated they would go towards a region of
cooler temperature, which means that they will travel radially outward from
the center of the earth. This will not be a one step operation but many steps of recombination and ionization until an equilibrium position is reached where the heat energy of the interior of the earth balances out the electrostatic forces of the positive charges in the interior. If there were a homogeneous mixture of positive and negative charges throughout the center of the earth, then there would be no magnetic field produced due to the rotation of the earth on its own axis.