PPC with a metal slab in plates
If a metal slab (dielectric constant K = ∞), thickness t < d is placed between the plates of a PPC, then due to the electric field between the capacitor plates the dielectric gets polarized & an electric equal to E0 is induced in it, as a consequence net electric field in dielectric is found to be zero i.e. Enet = 0.
Due to this field electric field net potential difference across the capacitor plates becomes
Using C = q/V, capacitance of capacitor becomes
If the conducting slab occupies the entire space available between the plates of capacitor i.e. when t =d & K = ∞, then C = ∞
Comparing (a), (b) & (c) we can say
CDS > CCS > Co