Any two conductors that are insulated and close to each other can be considered a capacitor, and these two conductors are the two classes of the capacitor. The process by which a capacitor is charged is called charging. At this point, one of the two plates is positively charged and the other is negatively charged by an equal amount. A charged capacitor has an electric field between its plates.
The loss of charge after charge is called discharge. When the two stages are connected, it begins to discharge. After discharge, there is no electric field between the two plates.
When the capacitor is charged, a voltage is generated between the two plates, so the ratio of the charge of the capacitor to the voltage between the plates is called the capacitance of the capacitor. Q represents the capacitance charge, U represents the voltage, and C represents the capacitance, so the formula is C=q/U.
The unit of the capacitor is F. The smaller units are UF (micro method) and PF (skin method), whose conversion relation is 1F=106 times micro method =1012 power skin method.
There are three common types of capacitors;
Fixed capacitor, its capacitance is fixed, according to the medium is divided into electrolytic capacitor, ceramic capacitor, mica capacitor, metal film capacitor, etc.
Its capacity can vary within a certain range. It consists of two sets of opposite metal plates, one set that does not move, called the fixed plate. Another set can be rotated, called dynamic slices. The capacitance can be changed by changing the relative areas of the two sets of metal plates.
It consists of two sets of small metal spring plates sandwiched between the medium. Adjusting the metal plate with a screw can change its capacitance in a small range.
Note: Some capacitors have polarity, do not connect wrong, otherwise it will be damaged.
In addition, the allowable error of capacitor capacitance value is divided into plus or minus 1%, plus or minus 2%, plus or minus 5%, plus or minus 10% and plus or minus 20% according to the accuracy. General capacitors are marked with capacitance, allowable error, rated voltage, pay attention to.