A crude model of the Earth’s magnetic field consists of a circular loop of current with a radius of 500 km with its center coincident with that of the Earth’s. Assuming the plane of the loop to be approximately in the equatorial plane, and using a value of 0.10 mT for the magnitude of the Earth’s field at the poles,
(a) Estimate the current in the theoretical loop.
(b) What would be the magnetic moment (magnitude and direction) of this supposed loop?