Final answer:
AC electrodes are made from inert materials like platinum to prevent chemical reactions during use. Magnesium can be used as a sacrificial electrode to protect other metals from corrosion.
Step-by-step explanation:
Electrodes designed for AC use are often made from materials that are inert and highly conductive so that they do not react chemically during use. A common material used for such electrodes is platinum, which remains stable and does not participate in the overall redox process in applications like sacrificial protection or powering various AC devices. Sacrificial electrodes can sometimes be made from materials like magnesium to protect underground tanks or pipes by sacrificing themselves to corrosion instead of the protected metal.