Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. The most common form of charge storage device is a two-plate capacitor. If the charges on the plates are +Q and −Q, and V gives the voltage difference between the plates, then the capacitance is given by » :C = frac where C in this case has the units of length. The dielectric constant for a number of very useful dielectrics changes as a function of the applied electrical field,… (More on Capacitance)