Parallel Plate capacitor; Formula for capacitance

A parallel plate capacitor is a simple type capacitor in which parallel plates of area A are separated by a distance 'd'. The plates are any shape of square, rectangular or circular. If 'd' is very small compared with the area of 'A', the electric field between the plates will be uniform as shown by equidistant parallel lines of force. However, the field will not uniform at the outer edges of the plates. This shown by curved lines of force in figure. This is called 'fringing' and can be neglected when d<A.

When there is no material in between the plates, air fills the space and acts as dielectric with air as the dielectric, the capacitance of the parallel plate capacitor in terms of plate area(A), distance between the plates 'd' is given by