Current Distribution on a Rotating Disk below the Limiting Current

The uniform current density on a rotating disk electrode at the limiting current is not achieved at lower currents because the edge of the disk is more accessible than the center as a result of the ohmic potential drop in the solution. The current distribution is calculated for well‐stirred solutions and also for lower rotation speeds where surface overpotential, concentration over‐potential, and ohmic drop are all significant. The current density at the center can vary between 50 and 100% of the average current density, and the ohmic potential drop to the center of the disk is 27.3% greater for the uniform current than for the primary current distribution.