Practical Capacitors:

It is out of the question to build a capacitor of the previous dimensions. Though, two sheets or strips of foil can be positioned one atop the other, divided by a thin, non-conducting sheet like paper, and then the entire assembly can be rolled up to acquire a large effective surface region. Whenever this is done, the electrical flux becomes great sufficient that the device exhibits important capacitance. Two sets of numerous plates can be meshed altogether, with air in among them, and the resulting capacitance is important at high ac frequencies.

In a capacitor, the electrical flux concentration is multiplied whenever a dielectric of a certain kind is positioned among the plates. Some plastics work well for this aim. The dielectric raises the effective surface area of the plates therefore a physically small component can be made to have a large capacitance. The Capacitance is directly proportional to the surface area of the conducting sheets or plates. Capacitance is also inversely proportional to the separation among conducting sheets; the closer the sheets are to each other, the better is the capacitance. The capacitance also based on the dielectric constant of the material among the plates. This is the electrostatic equal of magnetic permeability. The vacuum has a dielectric constant of 1. Dry air is around similar as a vacuum. Some substances have high dielectric constants which multiply the effective capacitance many times.

In theory, when the dielectric constant of a material is x, then placing that material among the plates of a capacitor will rise the capacitance by a factor of x as compared with the capacitance whenever there is only dry air or a vacuum among the plates. In practice, this is only true when the dielectric is 100 percent proficient-when it does not turn any of the energy contained in the electrical field into heat. It is also true only when all the electrical lines of flux among the plates are forced to pass via the dielectric material. Such are ideal scenarios, and while they can never be achieved absolutely, many manufactured capacitors come close.