If you have ever used your cell phone inside an elevator, you have surely noticed that the signal is lost and you cannot make or receive calls. This is due to neither more nor less than the Faraday Cage effect.
What is a Faraday Cage?
The Faraday Cage is a metal enclosure whose interior is protected against the action of external electromagnetic fields. It was conceived by physicist Michael Faraday, who noticed that a conductive material, such as a metal, reflects and deflects electromagnetic waves from the outside. In this context, an elevator made up of metal walls and ceilings behaves like a Faraday Cage in which cellular signals from the outside cannot penetrate the interior of the enclosure, leaving the phone without a mobile connection.
This effect can be verified with a home experiment that consists of covering a cell phone with aluminum foil and then trying to make it receive calls from outside. Cellular signals will not be able to penetrate that homemade Faraday Cage.
Beneficial effects of Faraday Cages
But not everything is negative in relation to Faraday Cages. On the contrary, it has beneficial effects that manifest themselves in a variety of situations. For example, during an electrical storm, a car or an airplane, due to its metal structure, works like Faraday Cages, protecting passengers from lightning bolts.
In research laboratories, the use of Faraday Cages is common to protect technical personnel from electrical overloads and electronic equipment from electromagnetic interference. Cables that transmit cable television or broadband Internet signals also use the Faraday Cage effect to block outside interference.
Finally, microwave ovens also behave like Faraday cages. The metal-lined cavity of the device prevents electromagnetic waves from escaping to the outside and producing harmful effects, but it is also intended to keep them confined and thus take better advantage of their cooking effect on food.