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Thermometer- How Does It Work?
The thermometers they use today are different than the ones Galileo may have used. There is usually a bulb at the base of the thermometer with a long glass tube stretching out the top. Early thermometers used water, but because water freezes there was no way to measure temperatures less than the freezing point of water. So, alcohol, which freezes at temperature below the point where water freezes, was used.
A thermometer is a tool that measures the temperature of things. The name is made up of smaller words: 'Thermo' means heat and 'meter' means to measure. You can use a thermometer to tell the temperature outside or inside your house, inside your oven, even the temperature of your body if you are sick.
Of the earliest inventors of a thermometer was probably Galileo. They know him more for his studies about the solar method and his 'revolutionary' theory (back then) that the earth and planets rotated around the sun. Galileo is said to have used a tool called a 'thermoscope' around 1600 - that is 400 years ago!!
Fahrenheit is named after the Italian physicist Gabriel D. Fahrenheit who developed his scale in 1724. Ice freezes at 32 degrees Fahrenheit (F for short), and water boils at 212 degrees F. They arbitrarily decided that the difference between the freezing point and boiling point of water ought to be 180 degrees.
The red colored or silver line in the midst of the thermometer moves up and down depending on the temperature. The thermometer measures temperatures in Fahrenheit, Celsius and another scale called Kelvin. Fahrenheit is used mostly in the United States, and most of the remainder of the world makes use of Celsius. Kelvin is used by scientists.
The Celsius scale is named after Anders Celsius. The Celsius scale was four times called the 'centigrade' scale. Centigrade means 'divided in to 100 degrees.' Anders Celsius developed his scale in 1742. They started with the freezing point of water and said that was 0 degrees Celsius (C for short). At the point where water boils, they marked that at 100 degrees C. This scale is much more scientific because the measurement is broken down in to an even 100 degrees. This is similar to the scientific method of measuring distance and weight called the metric method.
Kelvin is named after Lord Kelvin, whose full name is Sir William Thomson, Baron Kelvin of Largs, Lord Kelvin of Scotland. His scale starts at 0 degrees Kelvin, which is called absolute temperature.
Lord Kelvin took the idea of temperature step further together with his invention of the Kelvin Scale in 1848. The Kelvin Scale measures the coldest temperature there can be. They said there was no upper limit of how hot things can get, but they said there was a limit as to how chilled things can get. Kelvin developed the idea of Absolute Zero. This is at minus 273.15 degrees Celsius (or -523.67 F)! At this temperature, absolute zero is the lowest feasible temperature, occurring when no heat energy remains in a substance. Absolute zero is the point at which molecules do not move (relative to the remainder of the body).As far as scientists know, nothing in the universe can get that chilled!