Two flat plates parallel to each other and separated by a dielectric make up a flat capacitor. This is the simplest representative of capacitors, which are designed to store dissimilar energy. If the plates are given a charge equal in magnitude, but different in modulus, then the electric field strength between the conductors will double. The ratio of the charge of one of the conductors to the voltage between the plates of the capacitor is called the electrical capacity:
C=q/U
If the location of the plates is unchanged, then the capacitance of the capacitor can be considered a constant for any charge of the conductors. In the international system of measurements, the unit of electrical capacity is Farad (F). A flat capacitor has a strength equal to the sum of the strengths created by the conductors (E1 +E2 …+ En). Vector values. The electric capacitance value is directly proportional to the area of the plates and inversely proportional to the distance between them. This means,that, in order to increase the capacitance of the capacitor, it is necessary to make the area of the plates larger, while reducing the distance between them. Depending on the dielectric used, the flat capacitor can be:
- Paper.
- Mica.
- Polystyrene.
- Ceramic.
- Air.
Let's consider the principle of the device using the example of a paper capacitor. Paraffin-treated paper is used in this case as a dielectric. A dielectric is laid between two strips of foil, which act as conductors. The whole structure is rolled up into a roll, into which leads are inserted for connection to an electrical circuit. This model is placed in a ceramic or metal case. A flat air capacitor and other types of charge storage devices are of a similar design, only the materials after which the capacitor itself is named are used as a dielectric medium. When solving problems in which it is necessary to find the desired values, do not forget to use the value that characterizes the dielectric - the permittivity of the medium.
In radio engineering, liquid and dry types of capacitors are used. Liquid capacitors are an electrolyte solution in which an oxidized aluminum plate is placed. This substance is located in a metal case. The electrolyte used is a solution of boric acid and some other mixtures. Dry type of drives is madeby folding three tapes, one of which is aluminum, the other is metal, and between them is a gauze layer impregnated with a viscous electrolyte. The roll is placed in an aluminum case and filled with bitumen. The flat capacitor has a wide range of applications and low cost. Unfortunately, these models will not replace batteries for us, because the energy of a flat capacitor is very small, and the charge “leaks” very quickly. They are not suitable as sources of electricity, but they have one advantage - when charged through a low-resistance circuit, they instantly release the stored energy.
