Visualization of the Fleming’ s Left Hand Rule Using the Vortex Motion Caused by Motion of Ion Species During Electrochemical Reactions in the Magnetic Field

Abstract

To visualize the Fleming’ s left hand rule using ion species as charged particles in aqueous solution, the discharge reactions of the Daniel’ s cell and the redox reaction of Fe²⁺/Fe³⁺ were carried out under vertical magnetic field. A copper tube was united with a circular transparent acryl resin plate, which was employed as an electrolytic cell. A zinc or carbon rods was centrally inserted into the acryl resin plate of the cell. The cell was placed on a permanent magnets (neodymium and ferrite magnets) or an originally prepared electromagnet. The geometrical arrangement was shown in Fig. 5. The cell was filled with electrolyte solution : 0.1 mol/L CuSO₄ aqueous solution for the discharge reaction of the Daniel’ s cell and 0.1 mol/L H₂SO₄ aqueous solution containing 0.1 mol/L FeSO₄ and 0.1 mol/L Fe₂ (SO₄) ₃ for the redox reaction of Fe²⁺/Fe³⁺. The vortex motion of the electrolyte solutions originated from the Lorentz’ s force was clearly observed as soon as the cell reactions and the redox reaction took place under the vertical magnetic field caused by the electromagnet. The vortex motion visualized Fleming’ s left hand rule. The magnitude of the vortex motion was estimated by the rotation rate (rotation number a second) . The higher the rate became, the larger the electrolytic current of the redox reaction of Fe²⁺/Fe³⁺or the stronger the magnetic field was, which showed the quantitative relationship of the Lorentz’ s force. On the other hand, for the Daniel’ s cell, the rate decreased accompanying a decrease of the discharge current in time. The experiment was introduced for college students as estimators.