I want to know the usage of capacitor.

Capacitors are not necessarily columnar, but can also be flaky (ceramic), rice-grained (no feet, surface mount) and square (polyester film), many of which are not specified.

In the signal coupling circuit, it is mainly used to pass AC and block DC, in the rectifier circuit, it is mainly used for filtering, in the single-phase motor for phase-shifting starting, in the delay circuit for timing, in the high-frequency circuit for resonance, and so on.

How to identify the meaning of the code on the capacitor is popular in many countries, such as directly marking the data and using colors, which can't be written in more than ten pages. You'd better check the electrician's manual for details. Ask specifically if you don't understand.

How much voltage can the capacitor withstand-it's not obvious from the volume. Generally indicated on the capacitor. Some capacitors are small in size, but can withstand high voltage, such as the reverse capacitor of TV set.

On the first floor, the friend's foot-to-foot communication is an old almanac, which is not applicable now. Nowadays, many components are used to support the automatic plug-in machine (called bullet belt in the industry), and the feet of the products are often equal in length.