Cathodic Protection Tester Practice Exam

What type of current flows consistently in one direction?

1. Alternating current

2. Pulsed current

3. Direct current

4. Transient current

The correct answer is: Direct current

The correct answer is that direct current flows consistently in one direction. Direct current, commonly known as DC, is characterized by a unidirectional flow of electric charge. This means that, unlike alternating current (AC), which periodically reverses direction, direct current maintains a constant polarity and flows steadily in a single direction. This characteristic of direct current makes it essential for various applications, including battery-powered devices and electrochemical processes such as those used in cathodic protection systems. In cathodic protection, direct current is utilized to mitigate corrosion on metal structures by providing a continuous and stable flow that can effectively protect against corrosive elements. On the other hand, alternating current changes direction periodically, which does not provide the consistent flow required for effective cathodic protection. Pulsed current involves a series of pulses rather than a steady flow, and transient current refers to temporary current flows that can occur due to changes in the electrical system, making them unsuitable for applications requiring a constant flow like cathodic protection.