How do thermometers work?

Answer by  HilaryC (1382)

A thermometer works by the liquid inside the glass/plastic case heating up. When the liquid is heated up, it expands and travels up the tube. Mercury used to be used.

Answer by  RM49 (274)

When the heat in a room rises, the mercury inside the glass tube expands, showing you what the temperature is.

Answer by  GeorgeS58 (121)

The thermometer is a thin glass tube with a reservoir at the bottom. The reservoir is filled with mercury, inside the sealed tube is a vacuum (i.e., no air inside). As the temperature increases the mercury expands and rises up the tube which is marked for the corresponding temperature.

Answer by  jkc (258)

There are different types of thermometers that measure temperature the most common are glass thermometers used surgically that contain mercury or alcohol which expands proportionally to temperature.