Parallel Plate Capacitor (Without Dielectric) #8211; Most commonly used capacitor is parallel plate capacitor which consists of two charged parallel plates separated by a small distance. Capacitance of a parallel plate capacitor with vacuum between the plates is given by C = ε<sub>0</sub>A/d farad With Dielectric #8211; When a dielectric is placed between the capacitor plates, it polarises and produces an opposing field resulting in reduction of net electric field between the plates.