Back in 1836, a certain English scientist Michael Faraday conducted a very curious and informative experiment. According to his instructions, a large wooden cage was pasted over with sheets of tin paper (stanoli). Then it was isolated from the earth's surface and heavily charged with an electric machine. The potential difference of such a design with the earth was so strong that when approaching bodies connected to the earth's surface, sparks flew out from its outer surface. It is not surprising that this Faraday cage inspired fear in many witnesses. The English physicist himself was inside his structure, holding in his hands a very sensitive electroscope.
What did the Faraday cage reveal?
During the test, a fully operational device showed in the hands of a physicist the complete absence of an electric charge. And this means that such a design can be effectively used as a shield. Later it was possible to find out that the ability of such a screen to neutralize electromagnetic radiation largely depends on the thickness of its material, the depth of the surface effect and the ratio of the size of the openings to the length of the acting waves. Thus, the experiments of Faraday allowed people to find a way to protect sensitive equipment and human health from the harmful effects of a powerful electromagnetic field. This property has been widely used in practice, and it is difficult to imagine what would happen to humanity if it were not for the ingenuity and courage of a brave physicist.
How does the Faraday cage work?
When a closed electrically conductive shell enters an electric field, it begins to act on free electrons, as a result of which the opposite sides of this design acquire charges, which in turn create a field that completely compensates for the external effect. It should be noted that a Faraday cage can protect only from an electric field. A magnetic field, provided that it is static, freely penetrates inside. Therefore, the compass inside this design will work correctly. In the case of a dynamic electric field, the following thing happens: it creates a dynamic magnetic field, which, according to the laws of physics, generates its own changing electric field, which prevents the creation of a magnetic field inside such a screen.
Modern Faraday cages
At present, the phenomenon discovered by an English physicist is used for radio-frequency cabins, shielded rooms, and RF boxes. Such premises are widely used wherever it is necessary to protect a person from the electric field. As an electrically conductive material, now usually a fine metal mesh or perforated steel sheets are used, and the structures themselves are necessarily grounded in order to dissipate any electric currents that may arise from external radiation.
In addition, the Faraday cage is widely used for all kinds of tests of computer equipment, electronic components, etc. There are even special individual screening kits, and some companies offer shielding people their apartments for greater security.