A large parallel-plate capacitor with height d is filled with two layers of dielectric slabs. The dielectric constant of the layer between z=0 and z=0.8d is ∈ᵣ₁ and the dielectric constant of the layer between z=0.8d and z=d is ∈ᵣ₂. The bottom plate at z=0 is grounded and the top plate at z=d has a constant potential U₀. Assuming negligible fringing effect, determine the potential ∮ and electric field E inside the capacitor.