Define Capacitor Construction

In its most elementary state a capacitor having of two metal plates separated by a certain distance d, in among the plates lies a dielectric material with dielectric constant  =εoε, where εo is the dielectric of air. 

The dielectric material permits for charge to accumulate among the capacitor plates.  Air (actually vacuum) has the lowest dielectric value of εo = 8.854 x 10-12 Farads/meter. All other materials have higher dielectric values, since they are higher in density and can thus accumulate more charge.

The Physical meaning of capacitance can be seen by relating it to the physical characteristics of the two plates, so that, the capacitance is related to the dielectric  of the material in among the plates,