What phenomenon is caused by differences in potential between copper and steel in soil?

The phenomenon caused by differences in potential between copper and steel in soil is galvanic action. This occurs when two different metals, such as copper and steel, come into contact with an electrolyte, which is often moist soil, creating a situation where electrochemical reactions take place. In this scenario, the more noble metal (copper) does not corrode as readily as the less noble metal (steel). Instead, the steel tends to corrode faster due to the electrochemical potential difference between the two metals.

Galvanic action is essential to understand in many applications, especially in construction and infrastructure, where different metals may be used together. By recognizing how these metals interact and the potential for galvanic corrosion, steps can be taken to mitigate damage, such as using protective coatings or insulating materials to prevent direct contact.

The other options do not accurately describe this specific phenomenon. Electromagnetic interference refers to the disruption of electronic signals caused by electromagnetic fields, while static electricity build-up involves the accumulation of electric charge and is unrelated to the interactions between metals in soil. Corrosion, while related, does not specifically denote the galvanic process, which explicitly involves the interaction of dissimilar metals.