4. Consider a three slab geometry, where each slab carries a uniform charge density and has equal width W in the z direction and in?nite extent in x and y directions. In slab 1, extending over W < z < 2W; the volumetric charge density is given by rho1 = -4rho0, where rho0 is a positive number. In slab 2, which extends from -W < z < 0, the charge density is rho2 = rho0, while in slab 3, which extends from -2W < z < -W; the charge density rho3 = 3rho0. Determine and sketch the electric ?eld strength Ez(z) over the region -3W < z < 3W: Label both axes of your plot and denote the ?eld strength at each break point.Hint: Use superposition of shifted and scaled versions of the static ?eld con?guration of a single charged slab.