1. It has charging and discharging characteristics and the ability to prevent the passage of direct current and allow the passage of alternating current.

2. In the process of charging and discharging, the charge on the two plates has an accumulation process, that is, the voltage has a process of establishing, therefore, the voltage on the capacitor cannot be changed suddenly.

     The charging of the capacitor: the two plates are respectively charged with the same amount of different kinds of charges, and the absolute value of the charged amount of each plate is called the charged amount of the capacitor.

     The discharge of the capacitor: the positive and negative charges on the two poles of the capacitor are neutralized by the wire. There is a short current on the wire during the discharge.

3. The capacitive reactance of a capacitor is inversely proportional to frequency and capacity. That is to say, when analyzing the magnitude of capacitive reactance, the frequency and capacity of the signal must be related.