WEBApr 17, 2020 · Solution: e = V + Ir. Or, e – V = Ir. Or, (e – V)/I = r. Therefore, r = (3.0 – 2.8)/0.37 = 0.54 Ohm. Due to the Internal Resistance of the cell, the electrons moving through the cell turns some of the electrical energy to heat energy. Therefore, the potential difference available to the rest of the circuit is: