What is a thermometer and how is it used?

Answer 1

Thermometers are devices that measure temperature.

The Italian scientist Galileo invented the first air thermometer around 1600 and it has, and will continue to be, improved upon. A thermometer is often made from a sealed glass tube with a small amount of either Mercury metal or alcohol at the bottom. The mercury or alcohol changes volume as a function of its temperature (it expands when hotter), and will rise up into the shaft of the thermometer as it gets hotter. The hotter the temperature, the higher it rises. The temperature is simply read off markings on the tube at each height.

Temperature Scales

Early thermometers (like the one Galileo invented) did not have any scale (markings with numbers) to determine precise temperature.

The 1st precise scale was developed by Anders Celsius in 1742. He used 'degree' as the unit of temperature. All of his standards for comparison to make his markings (on his scale) were based on the properties of water.

Ø 0 degrees was assigned the temperature at which ice melts at sea level .

Ø 100 degrees was assigned the temperature at which liquid water boils at sea level.

Ø The region between (above and below, as well) these two extremes was separated into 100 equal units (degrees) .

Ø The two fixed temperatures that Celsius chose can be used to calibrate a thermometer.

Pressure also affects the freezing and boiling points of water. Extremely high pressure can cause ice to melt at a temperature below 0o (Ice skaters actually glide on a thin layer of water). Low pressure enables water to boil at a temperature below 100 degrees. (On top of Mt. Everest, water boils at 69 degrees).

Absolute zero is the coldest possible temperature - negative 273 degrees and is used by scientists. The Kelvin scale was developed by William Thomson - a.k.a. Lord Kelvin - and the markings on the scale are not called degrees, but are simply called kelvins. (0 degrees Celsius are equal to 273.15 Kelvin).
There is nothing called a "thermomoeter"

Perhaps you meant thermometer.

It is an instrument made to measure temperature.

There are many different ways to make a thermometer. One of the most common is to have a liquid that changes volume when its temperature changes (thermal expansion) inside a very narrow tube so that the small changes in volume of a reservoir (in a bulb) will be magnified and become easier to read.

1. Put the bulb where you want to measure the temperature
2. Wait until the system has stabilized (the liqid has stopped expanding)
3. Read the temperature