Is the obstruction to the free motion of positive & negative ions of the electrolyte by the viscosity of the electrolyte used in the cell. It is zero for an ideal cell. For a freshly prepared cell the internal resistance is very small & its value increases as the cell is put to more & more use. The internal resistance of a cell varies directly with distance of the electrodes concentration of electrolyte polarisation of the cell & varies inversely varies with the area of electrodes. Both emf & internal resistance are different for different cells & depends on the nature of electrolyte & nature of rods used.