What type of pressure does gauge pressure represent?

Gauge pressure specifically refers to the pressure measurement that is relative to the atmospheric pressure. This means that when gauge pressure is measured, it accounts for the ambient atmospheric pressure. So if a gauge reads 20 psi, for instance, it means the pressure is 20 psi above the atmospheric pressure at that location.

In the context of the other choices, the difference between absolute and atmospheric pressure captures a broader concept that does not focus solely on the gauge measurement, as it involves both absolute and atmospheric pressures. Similarly, total pressure is a measure that encompasses all pressures acting on a specific point, rather than focusing on the difference from atmospheric pressure alone. The maximum pressure in a system can refer to various conditions and does not specifically define gauge pressure as it could also include conditions above atmospheric levels without reference to ambient atmospheric conditions.