So these two electrodes are in there, so they're made from the same exact material. And what happens is we connect these guards to an outside power source, like a battery or a voltage cell. Now, what happens is this battery powers. It allows electrons to transfer in this direction. So if they transfer this way, that means this metal obtains these electrons. So this metal or electrode forms a negative charge, while this electrode forms a positive charge, because electrons will be taken away from this electrode.