A U-tube manometer is principally used to measure what?

A U-tube manometer is principally used to measure pressure, specifically the pressure difference between two points in a fluid system. It consists of a U-shaped tube partially filled with a liquid, often water or mercury, which responds to pressure changes by indicating a height difference of the liquid column. This difference is directly related to the pressure being measured, allowing for accurate quantification of pressure levels.

In practical applications, the manometer provides visual indications of pressure variations, which can be critical in numerous industrial and laboratory settings. The operation is based on the hydrostatic principle, where the height of the liquid column is proportional to the pressure exerted on one side of the manometer. Pressures can be positive or negative, relative to atmospheric pressure, and the U-tube manometer remains a fundamental tool in fluid mechanics and engineering for this reason.