The higher the distance from the coil the lower the magnetic field. But there is no limit in the spreading of the magnetic field. At some distance there is a problem with measuring the magnetic field because it is too low but it is there, also if you are 1000 miles away from the coil. The problem is: How strong shall the magnetic field be to do some effects and if the coil is too far away it may not be effective anymore.
So the magnetic field will penetrate the whole body. As the magnetic field of the Earth is doing right now.
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