Final answer:
The flux density in a capacitor with two dielectrics in series is the same across both materials, due to the conservation of charge and the fact that the same charge is present on each capacitor.
Step-by-step explanation:
The flux density in a capacitor that has two dielectrics in series is equal to the same flux density across both dielectrics. This occurs because the electric field across each dielectric material in series must be the same due to the conservation of charge and the fact that the same charge is present on every capacitor in the series combination. The flux (electric displacement) D is related to the electric field E by the equation D = ϵE, where ϵ is the permittivity of the dielectric material. However, even though the electrical field is the same, the charge induced on the surfaces of dielectrics may differ due to their respective dielectric constants.