Where practicable, contact between dissimilar metals anywhere in the system shall be avoided to eliminate the possibility of ___.

• A. induction
• B. osmosis
• C. galvanic action
• D. hysteresis

Answer: (C)

Dissimilar metals in contact in a conductive environment create galvanic action. When two different metals touch and there’s an electrolyte present, they form a galvanic cell: electrons flow from the more active (anodic) metal to the less active (cathodic) metal, causing the anodic metal to corrode faster. This is why you avoid putting different metals together in systems or you insulate them or use protective coatings to break the electrical connection. The other terms describe different phenomena (induction is magnetic/electrical, osmosis is solvent movement through a membrane, hysteresis is a lagging response in magnetic or other systems) and don’t describe the corrosion mechanism at play here.