A slab of material of dielectric constant K has the same area as that of the plates of a parallel plate capacitor but has the thickness d/2, where d is the separation between the plates. Find out the expression for its capacitance, when the slab is inserted between the plates of the capacitor

Now, the gap between plates is divided in two parts, for distance t there is electric field E and for the remaining distance (d—t) the electric field is { E }_{ 0 }

If V be the potential difference between the plates of the capacitor, then