Faraday cage, what it is, how it works and where it is used in the modern world

Back in 1836, the English physicist M. Faraday invented a device for shielding equipment from all kinds of electromagnetic fields. Despite the venerable age of the invention, it is still relevant today. This is a Faraday cage. I will tell you about it today.

What is a Faraday cage and how does it work

So, this device is a cage, which is made of metal with high electrical conductivity and in most cases is grounded. And the principle of operation of this device is extremely simple:

Under the influence of an external electromagnetic field inside the metal of the cell, free electrons begin to move. As a result, the opposite sides of the cell of the structure acquire such a charge that the field formed by it tends to compensate for the effect of the external electromagnetic field.

But a Faraday cage is unable to protect against a constant or slowly changing magnetic field. For example, in such a cage, the compass still correctly points to the north, which tells us that the earth's magnetic lines freely penetrate into the inner volume of the cage.

In order to screen high frequency radiation, the cell size must be smaller than the radiation wavelength.

Moreover, the effectiveness of shielding directly depends on the shape of the conductive material.

In this case, the following dependence is traced: the faster the electromagnetic field changes, the more the material resists the penetration of the field into the cell.

But at the same time, the following is also true: the higher the field frequency, the better it penetrates through the mesh with a fixed cell size.

If the source of an alternating electromagnetic field is placed inside an ungrounded Faraday cage, then it can be seen that electromagnetic waves are damped to a lesser extent than the incoming ones.

Note. It is a common misconception that the Faraday cage completely blocks the electromagnetic field. It (the cell) only minimizes its effect and the degree of this decrease depends on the following factors:

1. Cell size and electrical conductivity of the cell metal.

2. The frequency and shape of the electromagnetic wave.

3. Distance from the radiation source.

4. The power of the study source.

And it turns out that a cage made of solid sheets of steel is much more effective at suppressing radiation than any mesh.

The use of Faraday cells in the modern world

So, the principle of operation is clear and extremely simple, now let's see where such cells are used now. And for this we do not need to go to the laboratory, but just go into the kitchen and look at the microwave.

Its body is made of solid metal, and a special metal is applied to the transparent door perforated iron sheet with a cell from 1 to 3 mm, which successfully blocks radiation with a wavelength of 12 cm.

Also, if you look at the most ordinary television cable, you will see a shielding sheath in it, which is also a Faraday cage.

Modified cages are also used in special protective suits for service personnel of substations with voltages above 330 kV.

Even these few examples are enough to understand that the invention of the great M. Faraday lives and is very actively used in the modern world. If you liked the article, then like it and thank you for your attention!