Answer to Question #93203 in Electricity and Magnetism for Miracle Nnoli

Question

How would you screen a sensitive instrument from stray magnetic fields

Answer 1

To screen sensitive instruments from stray magnetic fields, a shield (or screen) is required. These stray magnetic fields may induce currents in the instruments and hence cause noise. A shield is a magnetic material with high permeability. This material, in which the instrument is enclosed, makes the magnetic field stay (enclose) inside this material and only small insignificant part of the field can pass through the shield. The instrument will be "insulated" from the magnetic field.

At home you can conduct a very simple experiment. Take a strong (neodymium for example) magnet and a steel nail or screw. Keep this piece of steel at some distance (1-2 cm) from the magnet. Of course this metal piece attracts to the magnet. However, if you take a thin steel plate and put it between the magnet and the nail, you'll feel that the attractive force disappears or becomes way more weaker. Congratulations, you isolated an object from the magnetic field.