Question

Why is the buoyancy bulb of small volume used in a hydrometer for heavier liquids?

Answer 1

1. Upthrust on the hydrometer used for heavier liquids is supposed to be more because upthrust is directly proportional to the density of the liquid.
2. Upthrust is also directly proportional to the volume of the buoyancy bulb of the hydrometer.
3. Using a low-volume buoyancy bulb ensures that there is no excess upthrust on the hydrometer.
4. If the upthrust is in excess, it will hamper the working of the hydrometer.

Hence, to minimize the upthrust on the hydrometer, the buoyancy bulb of the hydrometer for heavier fluids is made of small volume.