Using the Tafel equation, determine the activation polarization (voltage loss) associated with operation at 50 mA/cm2 and 500 mA/cm2 for: (a) a proton exchange membrane fuel cell with exchange current density of 10-4 A/cm2, and symmetry factor (transfer coefficient) of 0.5, (b) a solid oxide fuel cell with exchange current density of 0.1 A/cm2 and symmetry factor of 0.4. (c) Calculate these same losses using the Butler-Volmer equation. (d) Discuss any differences (or similarities) observed.