Science Common Sense

230 - How do thermometers measure temperature?

A thermometer measures temperature by using a liquid or a metal that changes shape when it gets hotter or colder.

Here's how it works: 1. The liquid (usually mercury or alcohol) is inside a narrow tube. 2. When the temperature around it increases, the liquid expands and rises up the tube. 3. When the temperature decreases, the liquid contracts and goes back down the tube. 4. The temperature is shown on a scale on the tube, so you can read the temperature easily.

Some thermometers also use electronic sensors or metal expansion to measure temperature. But the basic idea is the same: a change in temperature makes the liquid or metal change shape, which tells you the temperature.