The change in energy stored in the electric field will just be that corresponding to removing a volume (d1w)δx of dielectric-free space where the field is E 0 Volts/m and rep...The change in energy stored in the electric field will just be that corresponding to removing a volume (d1w)δx of dielectric-free space where the field is E 0 Volts/m and replacing it with the volume (wd) δx of dielectric material subject to the field E 2 plus the vacuum volume w(d1−d)δx subject to the field E 1 . This change in energy will be independent of the exact shape of the end of the slab providing that the extent of the non-un…