Answer to Question #93215 in Electricity and Magnetism for UduakObong Nicholas Luke

Question

How would you screen a sensitive instrument from stray magnetic fields

Answer 1

As we know, magnetic fields propagate infinitely in space. The reason why all magnetic materials do not attract to each other or why not all instruments suffer from noise can be explained by the fact that the intensity (or magnitude) of these fields decreases with distance. That is why it is not possible to fully isolate sensitive instruments from stray magnetic fields, but it is possible to decrease magnetic fields so that they won't influence the function of sensitive instrument. One can use a magnetic material with high permeability $\mu=0.063\text{ H/m}$ and more to make the field pass through that material and only infinitesimal part of the field that can't influence the sensitive instrument will reach the device we need to screen.