^PPC with a metal slab in plates

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. E_net = 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

C_DS > C_CS > C_o