What type of static charge is characterized by gradual extension under tensile stress?

The type of static charge characterized by gradual extension under tensile stress is known as creep charge. This phenomenon occurs when materials are subjected to mechanical stress over time, leading to a slow buildup of static electricity as the material deforms.

In the context of process safety management, understanding how materials can accumulate static charge during stress is crucial for preventing discharge events that could lead to fire or explosion hazards. Creep charge is particularly relevant in industries where materials experience continuous stress, as it highlights the importance of monitoring and managing static electricity to mitigate risks associated with ignition sources.

The other types of charges mentioned, such as brush charge, spark discharge, and corona charge, involve different mechanisms of static electricity generation or discharge. Brush charge, for example, refers to the transfer of charge due to contact and separation of materials. Spark discharge involves a sudden release of static electricity, which is more instantaneous compared to the gradual development seen with creep charge. Corona charge is related to the ionization of air near charged objects but does not correlate with mechanical stress in the same way that creep charge does. Thus, the focus on the slow and gradual nature of charge buildup under tension identifies creep charge as the accurate answer.