Which phenomenon results from contact of dissimilar metals in an electrical system?

• A. Induction
• B. Capacitance
• C. Galvanic action
• D. Hysteresis

Answer: (C)

Dissimilar metals touching in the presence of an electrolyte form a tiny electrochemical cell. The more active metal acts as the anode and corrodes, while the less active metal acts as the cathode. This electrochemical interaction, driven by differences in electrode potentials, is galvanic action. It can produce a small current and accelerate corrosion at the metal interfaces, especially in damp or salty environments. Induction involves currents from changing magnetic fields, capicatance is about charging between conductors separated by a dielectric, and hysteresis is the lag between magnetic field and response in a material. So the contact of dissimilar metals directly leads to galvanic action.