What type of electrical current is used in cathodic protection?

In cathodic protection, direct current (DC) is utilized to prevent corrosion on metal surfaces, particularly those that are buried or submerged in water. By applying a DC voltage, an electrochemical process occurs that reduces the oxidation reactions responsible for corrosion. This process effectively protects the anodic areas by providing electrons to the metal surface, turning it into a cathode and halting the corrosion process.

The choice of DC over alternating current (AC) is crucial in this application. AC can cause varying potential levels and is not effective in providing a consistent protective layer as it changes direction and intensity, making it less suitable for preventing corrosion.

Pulsating current, while it may have some applications in specific contexts, does not provide the steady and suitable conditions that DC does for cathodic protection. Therefore, identifying DC as the correct answer showcases an understanding of the fundamental principles underlying cathodic protection and its effective utilization in preventing corrosion.