The earth's magnetic field at the magnetic north pole is directed vertically downward and has a magnitude of 0.62 G. The earth's field is approximately that of a current loop located at the center of the earth.
(a) Find the magnitude and direction of the earth's magnetic moment.
(b) It is believed that the earth's magnetic field is produced by electric current in the earth's liquid metallic outer core. Suppose that the magnetic moment were produced by a current through a simple circular path of radius equal to the average radius of the outer core (2300 km). Find the direction and magnitude of this current.