Capacitors: the bascics, applications

A capacitor is a device designed for the purpose of storing a charge, similar to a battery, although it is unable to produce new electrons - it only stores them. The Basics: Like a battery, a capacitor has two terminals. Inside the capacitor, the terminals connect to two metal plates separated by a dielectric. The dielectric can be air, paper, plastic or anything else that does not conduct electricity and keeps the plates from touching …

…block DC voltage. If you hook a small capacitor to a battery, then no current will flow between the poles of the battery once the capacitor charges. However, any alternating current (AC) signal flows through a capacitor unimpeded. That's because the capacitor will charge and discharge as the alternating current fluctuates, making it appear that the alternating current is flowing. One big use of capacitors is to team them up with inductors to create oscillators.