Introduction

Capacitor is a passive electrical component, which consists of electrodes that are separated by a dielectric and have different electrical potential. It is used to store electric charge. The basic type of the capacitor is a plate capacitor. For more information visit http://en.wikipedia.org/wiki/Capacitor.

Preprocessing

Select "New" in the menu "File" and choose Electrostatic field, from dialog window. Program enters the properties settings mode. Here, choose Coordinate type "planar". Then click on the symbol of electrostatic field and set following values:

Fig. 1.: Editing of proprties of the problem

Geometry

Fig. 2.: Editing of the geometry

Boundary conditions

Select "New boundary condition" from the menu "Problem", or press Alt+B and gradually define three boundary conditions.

Materials

Select "New material" from the menu "Problem", or press Alt+M and define dielectric material embedded between the electrodes.

Processing

Mesh

Select "Mesh area" from the menu "Problem".

Solve

Select "Solve problem" from the menu "Problem", or press Alt+S.


Postprocessing

Calculation of capacity

Select "Volume integrals" from the toolbar and click into the area "Dielectric". In panel "Volume integrals" you ca find value of "Energy" in group "Electrostatic field".

Fig. 3.: Volume integrals calculation
Capacity of the capacitor can be then calculated according to formula

W_e = 4 \cdot \frac{1}{2} CU^2,
which can be adjusted to
C = \frac{W_e}{2 \cdot U^2}.