Question

A hydrometer is based on

• A. Principle of floatation
• B. Pascal's law
• C. Bernoulli's principle
• D. Principle of Relative density.

Answer 1

The correct option is A

Principle of floatation

It is based on the law of floatation which states that when a body is floating in a liquid, the weight of the whole body is equal to the weight of liquid displaced by the immersed part of the body. A hydrometer consist of a glass tube. In the glass tube there is a scale so calibrated that the reading on it levels with the surface of the liquid in which the hydrometer is floating, which indicates the number of times heavier or lighter the liquid is than water, i.e., the Relative density of the liquid.