A thermometer measures temperature through a glass tube sealed with mercury that expands or contracts as the temperature rises or falls. The tiny size of the bulb and micro-fine size of the tube help the mercury reach the temperature of what it is measuring very rapidly.

How does a thermometer work scientifically?

A thermometer has a glass tube sealed at both ends and is partly filled with a liquid like mercury or alcohol. As the temperature around the thermometer's bulb heats up, the liquid rises in the glass tube. ... When it is hot, the liquid inside the thermometer will expand and rise in the tube.

What are the 4 types of thermometer?