Editing Faraday cage (section)

==== Exterior fields ====
[[File:Skin depth by Zureks-en.svg|thumb|350px|Skin depth vs. frequency for some materials at room temperature, red vertical line denotes 50-Hz frequency:{{ubl
|Mn–Zn – magnetically soft [[Ferrite (magnet)|ferrite]]
|Al – metallic [[aluminum]]
|Cu – metallic [[copper]]
|steel 410 – magnetic [[stainless steel]]
|Fe–Si – [[grain-oriented electrical steel]]
|Fe–Ni – high-permeability [[permalloy]] (80%Ni–20%Fe)
}}
]]

Effectiveness of  the shielding of a static electric field is largely independent of the geometry of the conductive material; however, the static magnetic fields can penetrate the shield completely.

In the case of varying electromagnetic fields, the faster the variations are (i.e., the higher the frequencies), the better the material resists magnetic field penetration. In this case the shielding also depends on the [[electrical conductivity]], the magnetic properties of the conductive materials used in the cages, as well as their thicknesses.

A good example of the effectiveness of a Faraday shield can be obtained from considerations of [[skin depth]]. With skin depth, the current flowing is mostly in the surface, and decays exponentially with depth through the material. Because a Faraday shield has finite thickness, this determines how well the shield works; a thicker shield can attenuate electromagnetic fields better, and to a lower frequency.