This capacitor is the most common type, which is cheapest and simplest to construct.
It consists of two conducting plates parallel to each other and separated by a distance 'd', which is small when compared to the length of the plates. Practically the electric field is located between the two plates. There is a slight fringing of the field at its outer boundary. However, the fringing becomes less when the plates are brought more closer. There is a point when the fringing become neglected and field between the two plates are regarded to be uniform.
If there is vacuum between the two plates, then it can be proved that the electric intensity between two closely spaced parallel plates is given by
where 's' is the surface density of charge on either plate. If 'A' is the area of each plate and 'Q' is the charge on either plate, then
As the electric intensity is uniform between the plates, the potential difference is given by
V = Ed
where 'd' is the separation between two plates.
The capacitance of a parallel plate capacitor in vacuum is given as
