Abstract
The motion of the particles made of several kinds of materials between voltage applied electrodes is observed by a high speed camera. The motions are classified to three categories such as cyclic up and down motion, cyclic motion accompanying bounding, and motion with obvious staying at electrode. The classification is considered reasonably from the view point of the ratio of contacting time to electric relaxation time. The charge amount of the metal particle is estimated from the motion to be approximately saturation charge value induced by the external electric field.