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Canceling Earth's magnetism
Earth has a magnetic dipole moment of 8.0 X 10^22 J/T. (a) What current would have to be produced in a single turn of wire extending around Earth at its geomagnetic equator if we wished to set up such a dipole? Could such an arrangement be used to cancel out Earth's magnetism (b) at points in space well above Earth's surface or (c) on Earth's surface?
Shouldn't the answer to b and c be the same? If you cancel the dipole don't you cancel it for all points?
Customer support service by UserEcho
Yes, they would if the earth acted as a giant dipole then it would be true for every point outside of the Earth's dipole moment range.
Keep in mind that while current loops created a dipole moment, they are not point-dipoles or "perfect dipoles." At a large distance away, the fields look just like perfect dipole, but up close they do not.
Hope this helps!