Can a metal be used as a medium for a dielectric?

What is the dimensional formula for the intensity of polarization?

$A$ dielectric slab of dielectric constant $K$ is placed between the plates of a parallel plate capacitor carrying charge $q$. The induced charge $q^{\prime}$ on the surface of the slab is given by

The dielectric strength of air is . . . . . . .

The dielectric constant for a metal is

What happens if the magnitude of the capacitance of a capacitor is large? Define dielectric breakdown and dielectric strength.