Which of the following describes the working principle of a hydrometer?

💡 Solution & Explanation

A hydrometer operates on Archimedes' principle, which states that any floating object displaces a weight of fluid equal to its own total weight. By observing the depth to which the weighted glass bulb sinks in a liquid, one can directly determine relative density or specific gravity. This instrument is widely used in industries ranging from brewing to battery maintenance for testing fluid concentrations.