Double Math

Celsius Thermometer

Water’s freezing and boiling points are 0° and 100° respectively on the Celsius scale. As a result of the 100-degree interval between the defined points, the Celsius scale was invented by the Swedish astronomer Anders Celsius in 1742. To convert a Fahrenheit (°F) temperature into a Celsius (°C) value, use the following formula:

°C = 5/9(°F − 32).


There are three main components of the Celsius thermometer: a transparent thick glass tube, a capillary tube closed from one end, and a mercury bulb filled with mercury attached to the other end.


Celsius thermometers have no constriction above the mercury bulb, the scale goes from zero degrees Celsius to 100 degrees Celsius, and each degree is represented by one part.

A Celsius thermometer can reach a temperature of 200 degrees Celsius in some types. The lower fixed point on a Celsius thermometer is 0 degrees Celsius, the melting point of water or the freezing point of ice, and the upper fixed point is 100 degrees Celsius, the boiling point of water.

A thermometer may display two scales, one representing the Celsius scale (°C) and the other representing the Fahrenheit scale (°F).

0°C = 32°F

100°C = 212°F

Why mercury is preferred in making thermometers?
  • It is a good conductor of heat and can be seen through the thermometer glass, so mercury is used in thermometers.
  • The capillary tube wall does not adhere to mercury, as it is an expanding material that expands regularly. This makes mercury an accurate estimation.
  • Since it remains liquid between (−39°C) and (357°C), it can measure a wide temperature range.
  • Capillary tubes do not stick to their walls, so it returns to the bulb easily.

A thermometer might have two scaling systems, one for Fahrenheit and another for Celsius (°C).

How to Read a Celsius Thermometer?

Get to know how the Celsius temperature scale works. Under one standard atmosphere of air pressure, the Celsius scale is defined by the temperatures at which water freezes and boils. Water has a zero (zero) freezing point and a hundred (one hundred) boiling point. Every 100 degrees or parts of the temperature interval between are equal.

Temperature scales in Fahrenheit and Celsius should be understood. A water’s freezing point is 32 degrees Fahrenheit, and its boiling point is 212 degrees Fahrenheit. Therefore, 212 minus 32 = 180 degrees on the Fahrenheit scale. There are 1.80 Fahrenheit degrees for every Celsius degree. A Fahrenheit degree is equal to 5/9 of a Celsius degree.