π Inventions and machines π§ Machines and tools
Thermometers
π In short
A thermometer is an instrument that measures temperature. We use it to measure the air temperature to know if we need a coat, body temperature to know if we're ill, and the temperature of ovens, fridges and water.
π€© Did you know?
- Galileo invented one of the first instruments for measuring temperature around 1593.
- Water freezes at zero degrees Celsius and boils at 100.
- On the Fahrenheit scale water freezes at 32 and boils at 212.
- If your body temperature is over 38 degrees, you may have a fever.
π Find out more
π How does it work?
An old thermometer has a thin glass tube with colored liquid inside. When the liquid warms up it expands and rises up the tube, and when it cools it shrinks and falls, and we read the number beside it.
π The digital thermometer
A modern thermometer is electronic, with a small sensor that measures temperature and shows the number on a little screen. Some take the temperature from your forehead without touching it!
π‘ The Celsius scale
We usually measure temperature in degrees Celsius: water freezes at zero and boils at 100. Your normal body temperature is about 37 degrees.
π― Fahrenheit
Some countries, like the United States, use another scale called Fahrenheit, where water freezes at 32 degrees and boils at 212 degrees.
πΈ More pictures
𧩠Test yourself
1 What is roughly the normal temperature of the human body?
2 At how many degrees Celsius does water boil?
3 Water freezes at zero degrees Celsius and boils at ?? .
4 Which picture shows βThermometersβ?
π Discover more
π· Picture sources: Wikimedia Commons
- Menchi Β· CC BY-SA 3.0
- Original uploader was Tijuana Brass at en.wikipedia Β· CC BY-SA 3.0
