Task: Text Categorization
Input (English): quantum version of this quantity is equal to electron charge squared times the density of states at the Fermi energy and is used to describe two dimensional electron gases. For a concentric sphere with opposing charges on the spheres, this quantity is derived by first using Gauss's law to find the Electric Field between the spheres. Eventually, that method gives a value of 4 pi times the product of the two radii divided by the difference of those two radii for the concentric sphere. In (*) series, it is calculated as the harmonic sum of the individual values of this quantity, while in parallel, this quantity is additive. It is often calculated by dividing charge by voltage. For 10 points, name this quantity measured in farads, defined as the ability to store electrical charge.
Output (English): Science