In galvanic protection practice, which metal corrodes to protect the other?

• A. The more noble metal
• B. The less noble metal
• C. Both equally
• D. Neither

Answer: (B)

In galvanic protection, a metal pair in an electrolyte forms a galvanic couple where the more active (less noble) metal acts as the anode and corrodes, while the more noble metal stays protected as the cathode. The electrons flow from the less noble metal to the more noble metal, driving oxidation on the less noble metal and reducing reactions on the protected metal’s surface. This sacrificial behavior is how protection is achieved: the metal that corrodes away is the less noble one, intentionally sacrificing itself to shield the other metal from corrosion. For example, zinc anodes corrode to protect steel in marine environments. So the metal that corrodes to protect the other is the less noble metal.