Final answer:
The electric field between two infinite, charged parallel plates is constant and perpendicular to the plates, but becomes zero within a conducting slab placed between them.
Step-by-step explanation:
The electric field between two infinite, charged parallel plates is uniform and perpendicular to the plates. When these plates are separated by a conducting slab, the electric field within the conductor becomes zero due to the static equilibrium of charges in the conductor. The surface charge on the conducting slab rearranges itself such that the net electric field inside is neutralized. This scenario is an extended case of the parallel-plate capacitor concept, where an electric field E exists between the plates and is given by E = σ / ε0, with σ representing the surface charge density and ε0 the permittivity of free space. The field is considered constant and uniform as long as we are far enough from the edges of the plates.