A study on the physical behaviour of a dielectric slab inserted into a parallel-plate capacitor

Abstract

The aim of this study is not only to calculate the force acting on a dielectric slab and the direction in which this force acts, but also to provide the conceptual tools which allow for a correct interpretation of the phenomenon. The approach that we propose is based on energy considerations and it assumes the common simplifications which are made for such a system in an introductory physics course. Using graphical representations we have analysed the two situations which can be considered: a system at a constant charge and one at a constant potential difference. The differences found in both cases are discussed. The approach that we describe here is relatively simple and accurate, and it could help university level students to achieve a better understanding of the physical phenomena involved in the problem. Resumen. El objeto de este estudio no sólo es el cálculo de la fuerza que se ejerce sobre una lámina dieléctrica y el sentido en que actúa esta fuerza, sino también proporcionar las herramientas conceptuales necesarias para conseguir una correcta interpretación del fenómeno. El procedimiento que proponemos está basado en consideraciónes energéticas y asume las simplificaciones típicas que se tienen en cuenta en un curso de física general. Utilizando representaciones gráficas, analizamos las dos situaciones que pueden considerarse; sistema con carga constante y con diferencia de potencial constante. También discutimos las diferencias encontradas en ambos casos. El tratamiento que proponemos en este trabajo es relativamente simple y preciso, y podría ayudar a alumnos de un nivel universitario a una mejor comprensión de los fenómenos físicos implicados en el problema.

Electric power generation using a parallel‐plate capacitor

“…There are two situations that can be considered for any capacitor: (a) a system with constant charge and (b) a system with constant potential difference. The physical origin of the force acting on the dielectric slab is similar for both the cases …”

“…One of the objectives of the present study is to provide a novel method that overcomes the limitations and disadvantages of prior arts. As we know that the field is the physical origin of force acting on the partially inserted dielectric slab in a capacitor . The force on a dielectric slab at different positions (Figure ) with respect to plates of an isolated and charged parallel‐plate capacitor is expressed as …”

“…For partially inserted dielectric slab, the magnitudes of capacitance, electrostatic energy, and force acting on the dielectric slab depend upon the position of the dielectric slab. 24 Let us consider the case that the charge (Q) on the capacitor plates is constant. The capacitor is charged to voltage V c , and the voltage source is then disconnected.…”

“…As motion of conducting and dielectric plates is against the electrostatic force, mechanical force must be applied. The origin of force on partially inserted dielectric slab is nonuniform electric (fringing) field . This force originates from interaction between free charges on capacitor plates and the polarization charge on the dielectric surface .…”

“…The origin of force on partially inserted dielectric slab is nonuniform electric (fringing) field. [23][24][25] This force originates from interaction between free charges on capacitor plates and the polarization charge on the dielectric surface. 26 These mechanical forces can be driven by human or/and machine motion, eg, motor or slowmoving piston of a stirling engine.…”