# Current Loop equivalent to Earth's Magnetic Field

by .Scott
Tags: current, earth, equivalent, field, loop, magnetic
 P: 385 I'm trying to get a feel for the overall magnitude of the Earth's magnetic field. If I placed a superconducting belt around the Earth magnetic equator, how much current would that loop have to carry to approximate the Earth magnetic field? Currently, the field at the equator is about 31 microT and at 50 degrees latitude is about 58 microT. If I replace the Earth with a vacuum, it looks like I would need on the order of 20MA - but I have no confidence in that estimate. It looks to me as though the Earth's iron content might bring this number down.
 PF Gold P: 1,827 This document appears to have all the necessary data to answer your questions: The US/UK World Magnetic Model for 2010-2015 http://www.ngdc.noaa.gov/geomag/WMM/...010_Report.pdf
P: 385
 Quote by Bobbywhy This document appears to have all the necessary data to answer your questions: The US/UK World Magnetic Model for 2010-2015 http://www.ngdc.noaa.gov/geomag/WMM/...010_Report.pdf
That all very incredibly detailed - but I would settle for and answer that's off by a factor of 2.
I have the basic data and the B=uI/2R formula (for the center of a current ring). What I don't have is any experience calculating magnetic fields directly from currents - so I am very uncertain of my computations.

Also, the B=uI/2R is for the center of a current ring, not on the surface of a sphere girdled by a current ring - so I don't have a direct comparison. The B=uI/2R also assumes a constant permeability (u) which is not the case of a solid sphere hanging in a vacuum.

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