🔍 Key Concepts

• cathodic protection and how it prevents corrosion • difference between impressed current systems and sacrificial anode systems • what role zinc anodes traditionally play on a ship's hull

💭 Think About

• Ask yourself: when we add electrical current to protect steel, what older corrosion‑control method is this modern system improving on? • Which of the answer choices is directly related to corrosion control of steel in seawater rather than magnetic influence or cosmetics? • Think about how ships were commonly protected from rust below the waterline before impressed current systems became widespread.

✅ Before You Answer

• Identify which options are specifically about corrosion protection of underwater steel surfaces. • Eliminate options that deal mainly with appearance (cosmetic coating) or magnetic fields rather than electrochemical corrosion. • Recall that traditional hull protection often used blocks of a more active metal attached to the hull—match that idea to the correct choice.