Are capacitors and capacitors the same?

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It is generally considered that capacitors and capacitors are the same. What people usually call capacitance refers to capacitors. A capacitor consists of an insulating dielectric sandwiched between two metal electrodes.

Capacitance is a physical quantity that describes the performance of a conductor or conductor system to hold an electric charge.

The capacitance of the isolated conductor charges the charge Q to the isolated conductor, its potential U is proportional to Q, Q/U has nothing to do with Q, only depends on the shape and size of the isolated conductor, it reflects the ability of the isolated conductor to hold the charge, so it is defined as the capacitance of the isolated conductor, expressed by C, C = Q/U. The capacitance of an isolated conductor is equal to the amount of electricity required for the conductor to raise its unit potential. The international unit of capacitance is the farad, abbreviated as the method, which is denoted by F and is a very large unit. If the Earth is considered an isolated conductor, its capacitance is only 709×-6 method, so it is usually measured in μF (=-6F) or pF (=10-12F).

If another negatively charged conductor is moved closer to an isolated conductor, the potential of the latter decreases, and it can be seen that the potential of a non-isolated conductor is not only related to the amount of electricity it carries, but also depends on the relative position of other surrounding conductors.

Capacitor If the charged conductor A is surrounded by a closed conductor cavity B, the potential difference between AB is not affected by the charged body outside the cavity due to the shielding effect of the cavity, and the amount of electricity carried by A is proportional to the potential difference between A and B.

In fact, the limit of cavity sealing is not too high, even if the two conductors A and B are a pair of conductor plates (coaxial cylindrical or parallel planar plates) that are not much apart, if QA is the amount of electricity on the side opposite conductor B on conductor A, the above proportional relationship remains unchanged. This pair of conductors insulating each other forms a capacitor, and this pair of conductors is called a pair of plates of the capacitor.

Connect the voltage U to a pair of plates of the capacitor, and they obtain a charge of equal magnitude and opposite signs±Q, and the potential difference UA-UB=U defines the capacitance of the capacitor as C=Q/U. Capacitance is the characteristic constant of the capacitor, which depends on the shape, size and relative position of the two conductors; When the conductors are filled with insulating material, the capacitance of the capacitor is also related to the relative passivity εr of the insulating material. If εr is related to the strength of the electric field, the capacitance C will change with the applied voltage U, and this capacitor is called a nonlinear capacitor.

The reciprocal of the capacitance 1/C=U/Q=S is called the inverted capacitance.

The capacitance formula for a simple capacitor is shown in the table.　Parallel and series connection of capacitors n capacitors are connected in parallel as shown in Figure A, their voltages are equal to u, and the charged charges are Q1, Q2 、...、 QN. The total charge q= obtained by this parallel combination is C=, i.e. the total capacitance of the shunt capacitor bank is equal to the sum of the capacitors. 　n capacitors are connected in series as shown in Figure B, they are charged with equal charge Q, and the voltages are U1, U2、...、un, respectively. The total voltage u=of this series combination is S=, i.e. the total inverted capacitance of the series capacitors is equal to the sum of the respective inverted capacitors.

Performance parameters and uses of capacitors Capacitance is one of the main performance parameters of capacitors. In addition, the performance parameters of the actual capacitor are withstand voltage (or operating voltage), loss and frequency response, which depend on the breakdown field strength, medium loss and frequency response of the charged medium, respectively.

There are many types of actual capacitors and different uses. Large power capacitors are mainly used to improve the power factor of power equipment to reduce transmission losses and give full play to the efficiency of power equipment. Capacitors are widely used in electronics to provide AC bypass stabilized voltage, as interstage AC coupling, and as filters, phase shifters, oscillators, and so on.