The simplest general equation for the capacitance(effectiveness holding a charge) of a capacitor isC=?A/z. The three variables are: ?, the permittivity or polarizability of the insulating layer (in this case the glass or plastic); A, the total area of either conductive layer in contact with the insulator; and z, the thickness of the insulating layer: What are the three ways to improve a Leyden Jar, in theory, based on this equation?