The motion of carbon powder in a vibrating vessel has been investigated by measuring electrical conduction through the powder bed. The carbon powder used in this study consisted of spherical particles with the diameter of 80∼180μm and with the bulk density of 0.9g/cm3. The sample powder was packed into an acrylic vessel equipped with nine pairs of electrodes. The vessel was oscillated vertically by a vibrator and the electric current flowing horizontally through the powder bed was measured. Both the effective current and the cyclic shape of the current varied with the frequency and the maximum acceleration of oscillation. When the maximum acceleration was less than 1g, the duration in which the current was off, was not found in a period of oscillation. On the other hand, when the maximum acceleration was increased beyond about 1g, the duration in which the current was off, appeared. This is attributed to the appearance of the duration in which the particles fall freely without exertion of forces on each other. An exceptionally steep decrease in the effective current was found when the maximum acceleration exceeded about 1g. The critical acceleration which caused the steep decrease in the effective current became greater as the location of electrode was lowered. This is due mainly to the frictional forces between particles. The shape of current associated with the oscillation of powder bed was sinusoidal up to the maximum acceleration of about 1g and deviated from the curve beyond 1g. The phase lag in the oscillation of current against that of the vessel was also measured. The resonance phenomena between the frequency of oscillation and that of the alternating electric field applied to the electrodes were observed.
