Question

On what principle is a thermometer based?

Answer 1

ANSWER

thermal expansion

These liquid thermometers are based on the principal of thermal expansion. When a substance gets hotter, it expands to a greater volume. Nearly all substances exhibit this behavior of thermal expansion. It is the basis of the design and operation of thermometers.

Answer 2

$\huge\sf{Answer:}$

Thermometers are based on the principle of expansion in liquids.

When temperature increases mercury inside the thermometer expands to give reading of temperature.