Hydrometer

A densimeter or hydrometer is a bulb-shaped instrument with a projecting stem, designed to measure the density of liquids. Hydrometers are commonly used for quick and operational density measurements. Each hydrometer is calibrated for a specific range of liquid densities. In the model shown, the hydrometer is designed for measuring the density of water. When the hydrometer is immersed in a liquid, it floats at a certain depth based on the liquid's density, following Archimedes' principle. This principle states that the depth of immersion of the bulb and stem depends on the density of the liquid. If the hydrometer is placed in a liquid with a density similar to that of water, the stem will float at a specific depth, and the scale on the stem will indicate the density in kilograms per cubic meter (kg/m³). When placed in a liquid with a higher density, the hydrometer will float closer to the surface, while in a lower-density liquid, it will sink deeper.