ABSTRACT
Electrostatic force per unit area is the mechanical pressure due to electrostatic field acting on the conductor–dielectric boundary. In electrostatic field, due to the presence of surface charges on the boundary, there is always a mechanical pressure that acts on any boundary. Mechanical pressure due to electrostatic field that act on a dielectric–dielectric boundary arise due to two reasons. The first one is the polarization of atoms and/or dipoles in the volume of the dielectric media under the action of electric field, while the second one is the change in the polarization vector that takes place at the boundary between two different dielectric media. If a charged parallel plate capacitor with air between the plates is partially submerged in a liquid dielectric then the mechanical force on liquid–air boundary within the capacitor will act from the liquid dielectric to air, as the permittivity of air is smaller than the permittivity of liquid dielectric.
