Kinds of optically induced force derived from laws of conservation of the momentum and energy

Abstract

Optically induced forces (OIF) applied to a transparent optical medium are analyzed. We deliberately do not use any assumptions about a nature of optically induced force and analyze thought experiments where only notions and laws of conservation are used. Two unambiguous but contradictory thought experiments are used as a ground of an analysis. It is shown that only two kinds of well-known OIF is sufficient to match contradictory results of the experiments. This is the kind of density force known in electrostatics that is responsible for the density force arising in an inhomogeneous dielectric located in an electrical field. This is the Abraham density force arising at propagation of a light pulse in an optical medium. The force is located in the regions of the optical medium where leading and trailing edges of a light pulse are propagating. OIF in a homogeneous optical medium located in an inhomogeneous electrical field is equal to zero at a steady-state. This result contradicts to that obtained by means of the widely used approach based on the Lorentz density force.