Question

Which of the following cases in which the metal structure is protected?

(a) Current passes from metal to electrolyte

(b) Current enters it from the electrolyte

(c) Electrical contact with dissimilar metals

(d) Connecting the positive terminal of the power supply

This question was posed to me by my school teacher while I was bunking the class.

This is a very interesting question from Cathodic and Anodic Protection topic in chapter Corrosion Prevention of Corrosion Engineering

Answer 1

The correct answer is (b) Current enters it from the electrolyte

The best explanation: Metallic structure can be protected when the impressed current is arranged to enter it from the electrolyte. Whereas current passes from metal to electrolyte, electrical contact with dissimilar metals, and connecting the positive terminal of the power supply results in accelerated corrosion.