Corrosion products increase the electrical resistance of what between surfaces?

The correct choice refers to how corrosion products can significantly impact the electrical performance and conductivity between surfaces, particularly at a joint. When corrosion occurs, it generally results in the formation of oxide layers or other corrosion by-products that can accumulate at the interface where two conductive materials come together. These products can act as a barrier, increasing the electrical resistance across the joint.

In avionics systems, where reliable electrical connections are essential for proper functionality, the increased resistance due to corrosion at a joint can lead to issues such as signal degradation, overheating, and ultimately, system failure. Understanding how corrosion impacts joints is crucial for effective maintenance and prevention strategies in avionics applications.

The other choices do not adequately represent the primary concern associated with corrosion; for instance, while corrosion can affect connectors or insulators, the specific context of increased resistance is most clearly evident at a joint where two conductive surfaces meet, making that the focus of the correct answer.