What is a capacitor? In a way, a capacitor is a little like a
battery. Although they work in completely different ways,
capacitors and batteries both store electrical energy. Inside
the battery, chemical reactions produce electrons on one
terminal and absorb electrons on the other terminal. A capacitor
is much simpler than a battery, as it can't produce new
electrons -- it only stores them. Inside the capacitor, the
terminals connect to two metal plates separated by a non-
conducting substance, or dielectric. You can easily make a
capacitor from two pieces of aluminum foil and a piece of paper.
It won't be a particularly good capacitor in terms of its
storage capacity, but it will work. In theory, the dielectric
can be any non-conductive substance. However, for practical
applications, specific materials are used that best suit the
capacitor's function. Mica, ceramic, cellulose, porcelain,
Mylar, Teflon and even air are some of the non-conductive
materials used. The dielectric dictates what kind of capacitor
it