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How do thermometers work? |
by Mya Kagan (whyzz writer) >> more about the author
Keepin' Cool!
It's easy to see for yourself the way the liquid inside of a traditional thermometer rises from warmth and gets lower as it cool down.
Take a liquid thermometer and leave it sitting out on a table for a few minutes. The temperature it shows will be the same as the temperature in the room.
Pour a glass of ice water, and stick the tip of the thermometer into the water. Watch the way the liquid quickly shrinks down as it picks up on this new change in temperature!
Now, stick the end of the thermometer into a glass of warm water, and watch what happens! The red liquid inside will quickly shoot back up, showing you that it's now detecting a warmer temperature! Cool!!
Thermometers are special devices that are used to determine temperature – that is, how hot or how cold something is!
One of the most common kinds of thermometers looks like a long, enclosed, clear tube with colored liquid inside (often red). The type of liquid inside the tube naturally expands and gets bigger as it gets warmer and gets smaller as it cools down. This causes the liquid to climb up the thermometer when it detects heat, and to drop down when it detects cold. The outside of the thermometer has a scale on it, which tells you what temperature the liquid has detected!
Lots of people now also use digital thermometers. Instead measuring temperature by how much a liquid does or does not expand, most digital thermometers use sensors that detect heat. Some of these measure from inside your ear or under your tongue to tell you the temperature of your body!
The most common temperature measurements are degrees of Fahrenheit and Celsius. These scales give numbers to certain temperatures based on how cold it must be for water to freeze, and how hot it must be for water to boil. The scales assign certain degrees to these measurements so that we can use them to talk about freezing, boiling, and everything in between!
Keepin' Cool!
It's easy to see for yourself the way the liquid inside of a traditional thermometer rises from warmth and gets lower as it cool down.
Take a liquid thermometer and leave it sitting out on a table for a few minutes. The temperature it shows will be the same as the temperature in the room.
Pour a glass of ice water, and stick the tip of the thermometer into the water. Watch the way the liquid quickly shrinks down as it picks up on this new change in temperature!
Now, stick the end of the thermometer into a glass of warm water, and watch what happens! The red liquid inside will quickly shoot back up, showing you that it's now detecting a warmer temperature! Cool!!
