A solid material fuse is typically filled with which substance?

The correct answer is that a solid material fuse is typically filled with compressed boric acid. This substance, boric acid, is used in fuses due to its properties as a non-conductive material which helps to effectively snuff out electrical arcs and extinguish the heat generated during a fuse operation.

Boric acid also has a relatively high melting point and thermal stability, making it efficient in preventing undesired conduction. This contributes to the safety and reliability of the fuse, ensuring that it can perform effectively under various electrical load conditions.

While other substances might be used in different contexts, they do not serve the same purpose as boric acid in solid material fuses. Compressed air, for example, is not suitable due to its conductivity and inability to absorb heat effectively. Liquid mercury, while it can conduct electricity, poses significant safety risks and does not function adequately within the context of a fuse. Sand, although it can offer certain insulating properties, lacks the specific chemical properties of boric acid that enhance fuse performance. Thus, the use of compressed boric acid is the best choice for solid material fuses.