Could you ever imagine standing under a copper mesh roof and your mobile phone instantly looses its signal? That is exactly what Will, played by Johnny Depp in Transcendence, built in order to prevent any electronic eavesdropping or connections.
Only if it were true. In fact, what they were making reference to was the Faraday cage. A lot of buildings act as Faraday cages, too, if only by accident. With their plaster or concrete walls strewn with metal rebar or wire mesh, they often wreak havoc with wireless Internet networks and mobile signals.
A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. A Faraday cage operates because an external static electrical field causes the electric charges within the cage’s conducting material to be distributed such that they cancel the field’s effect in the cage’s interior. This indeed does stop electronic transmissions but requires one to be totally enclosed in the cage. Not just under a copper mesh roof. In point of fact any metal will do and you don’t have to use copper.
This phenomenon is used, for example, to protect electronic equipment from lightning strikes and electrostatic discharges. That is the case of lightning rod or lightning conductor that we see on top of buildings engineered to protect the structure in the event of lightning strike.
But the shielding effect most often benefits humankind. Microwave ovens reverse the effect, trapping waves within a cage and quickly cooking your food. Screened TV cables help to maintain a crisp, clear image by reducing interference. MRI (magnetic resonance scanning) is a more sophisticated form of the Faraday cages. MRI scans rely on powerful magnetic fields to create medically useful scans of the human body. MRI rooms must be shielded to prevent stray electromagnetic fields from affecting a patient’s diagnostic images. In fact, you can build your own Faraday Cage at home. Many websites such as National Geographic actually teach you how to build your own Faraday Cage with a simple solution.
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Source: Wikipedia, science.howstuffworks.com
Camilla G.//SMC Editor
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