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Electromagnetic shielding
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Metal enclosures block fields.
Conductive enclosures block EM waves by reflection and absorption (skin depth). Needed in sensitive electronics and MRI rooms.
Cables with braided shields.
Holes must be smaller than the wavelength.
In more detail
Electromagnetic shielding uses conductors to block electromagnetic fields, reducing interference. Metal enclosures and mesh cages attenuate radio and electric fields.
Real-world uses
- Electronic devices are shielded to avoid interfering with other equipment.
- Shielded cables protect signals from noise.
- Hospitals and electronics labs use metal enclosures to block electromagnetic interference from nearby equipment.
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Frequently asked questions
Does a metal box block all fields?
It blocks electric fields and high-frequency radio waves well, but static magnetic fields need high-permeability shielding.
Does the shield need to be solid?
A fine mesh works well for most radio frequencies.
Does a metal box block all radio waves?
Most of them, provided there are no large openings compared with the wavelength.
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