EXPERIMENT ON THE MOTION OF A DIELECTRIC IN A PARALLEL-PLATE CAPACITOR

This article describes a relatively simple arrangement which can be us ed to study the motion of a dielectric slab in a parallel-plate capaci tor. An aluminum cart fixed above a linear air track, together with th e track itself, forms the capacitor, and a plastic rider serves as the dielectric. The electric force on the dielectric, partially withdrawn from the capacitor, is found to be proportional to the square of the voltage applied to the plates. Results for the motion of this dielectr ic are given for a fixed potential difference across the plates. A sim ple model including a frictional force is presented to describe this m otion.