4. The plates of the parallel-plate capacitor shown in the figure has an area of A and a separation of d. Assume that the electric field in the medium has only a z component. The upper plate is held at a potential of Vo-and the lower plate is grounded. The dielectric between the two plates has a permittivity of e = az", where a and n are constants.

(b) Determine the electric field intensity in the medium, (c) Determine the potential distribution in the medium, (d) Determine the electric flux density in the medium, (e) Determine the charge distribution on each plate, and (f) the capacitance of the parallel-plate capacitor.