Capacitor is a kind of can store charge container. It is made of two pieces of sheet metal, who get close to, such as: mica, ceramic dielectric. Paper, electrolytic capacitor, etc.

On the structure, is divided into fixed and variable capacitor capacitors. Capacitors of dc resistance of infinity, namely with separated dc capacitor. Capacitor resistance affected by alternating current frequency of alternating current (ac), meaning that the same capacity of capacitor varies with different frequency of the alternating current capacitive reaction.

This is because the capacitor is depend on its charge and discharge function to work, when the power switch is not closed. Capacitor of two pieces of metal plate and other common metal plate sample is not charged.When switch S closed, the capacitor is the free electrons on the plate was attracted by the power, and pushed to the negative plate.Because of the capacitors between the plates have insulation materials, so ran from the positive plate of the free electrons in the negative plate piled up on top. Positive plate for electronic reduce bring positive and negative plate will bring a negatively charged by electronic gradually increase.There is the potential difference between the two plate capacitor, when the potential difference equals the supply voltage,Capacitor charging stop. 

At this point if cut off the power supply, stays a charging voltage capacitor.For the capacitor charging, if we use wire connects two plate, due to the potential difference between two plates, electronic will be through a wire, back to the positive plate, until the potential difference between the two plates is zero. Capacitor neutral state back to live, no current in the conductor. 

                                                                                               Dingfeng capacitor --  the Characteristics of Capacitor