There are numerous uses for magnetic shields in research and consumer electronics. In geophysical research, magnetic shields are used in paleomagnetic laboratories to protect samples and improve the performance of sample magnetometers. Research shields range in size from 10 cm to 15 m.
The irony in magnetic shielding theory is that a shield actually adds another magnetic field. This new field is specifically designed to be equal and opposite to the existing field, resulting in a nullification of, not a removal of the ambient magnetic fields. This is analogous to gravitational forces at Lagrangian points, or the balance of centripetal and gravitational forces on orbiting bodies, or noise cancellation by antiphase headphones.
Diverse materials and techniques are used for magnetic shielding. The choice depends on the kind of fields to be opposed (e.g., AC vs DC) and the specific application. In general, shielding can be accomplished by using one of two physical phenomenon,...
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