A parallel-plate capacitor of plate area and separation is connected to a battery…
PHYSICS · Multi-part · CBSE · Physics · Electrostatic Potential and Capacitance · Electrostatic Potential and Capacitance
Problem
A parallel-plate capacitor of plate area A and separation d is connected to a battery that maintains a constant potential difference V0. A dielectric of constant κ and identical thickness d fills the space between the plates. An experimenter now slowly and uniformly withdraws the dielectric slab completely out of the capacitor while the battery remains connected. The process occurs quasistatically so that mechanical forces are balanced at every moment, and frictional forces are negligible.
(a) Determine expressions for the electrical energy stored in the capacitor (i) before any of the dielectric is removed and (ii) after the dielectric is completely withdrawn.
(b) Calculate the mechanical work Wext that the experimenter must perform to remove the dielectric slab fully. Express your answer in terms of A, d, V0, κ, and fundamental constants.
(c) During the removal process, energy is transferred among different forms. Identify each form of energy that changes and explain, using energy conservation, how the value of Wext you obtained in part (b) is consistent with those changes.