Which type of capacitor is least likely to be classified as a high-voltage capacitor?

High-voltage capacitors are typically required to handle higher electrical potentials without breaking down or failing. Electrolytic capacitors are primarily designed for low to medium voltage applications because they rely on a thin oxide layer for their dielectric. This oxide layer can only withstand relatively low voltage levels, often making them unsuitable for high-voltage applications.

In contrast, film, ceramic, and tantalum capacitors can effectively operate at higher voltage levels. Film capacitors, with their robust dielectric materials and higher voltage ratings, are often used in high-voltage situations. Ceramic capacitors can also handle high voltages, depending on their construction and class, particularly Class 1 ceramics. Tantalum capacitors, while more sensitive to voltage, can be designed for specific high-voltage applications as well.

Given these characteristics, electrolytic capacitors are the least likely to be classified as high-voltage capacitors. They have limitations stemming from their design that restrict their application in high-voltage scenarios compared to the other types mentioned.