Different types of thermometers

Thermometers are not a strange instrument to us. We all know what is a thermometer and its uses? Through this article I explain about the various types of thermometers. Also this article contains the peculiarities of the thermometer, the history of the thermometer and the units used in the thermometers for measuring temperature.

Thermometer is the device which used to measure the temperature. We could able to find the level of temperature easily with the help of a thermometer. We use thermometer in our daily life. There are different types of thermometers. Through this article I explain about them. Read on.

History of the thermometer

It was Galileo Galilei the first man who made the equipment to measure the temperature of a body. It was in 1592. But it didn't help to measure the temperature correctly. Thus many scientists tried to develop more accurate one. At last an ideal equipment to measure the temperature came into effect through the hands of Daniel Gabrial Fahrenheit in 1714.

Different types of thermometers

There are different types of thermometers around us. They are:
1. Liquid Thermometer
2. Gas Thermometer
3. Resistance Thermometer
4. Thermo Electric Thermometer
5. Vapour Pressure Thermometer

Liquid Thermometer

In this thermometer the expansion of liquids is used. Mercury thermometer and Alcohol thermometer are good examples for the liquid thermometer. Mercury or Alcohol will be filled in a capillary tube. When the temperature increases the mercury or alcohol inside the tube will expand and we could able to identify the temperature easily.

Gas Thermometer

When the gas filled in the container is heated the pressure increases. This change is made utilized in the gas thermometers. Hydrogen gas thermometer is one example for the gas thermometer. It has a range of -2500 °C to 15000 °C.

Resistance Thermometer

Resistance Thermometers are also known as Resistance Temperature Detectors or Resistive Thermal Devices (RTDs). As the Resistance Thermometers are also made using Platinum, they are also called Platinum Resistance Thermometers (PRTs). The resistance of a current carrying conductor changes with temperature. This principle is utilized in the construction of the Resistance Thermometer.

Thermo Electric Thermometer

Thermo Electric Thermometer is a thermometer which utilizes thermo electric current to measure the temperature. The ends of two different types of conductors are joined. If the connections are in different temperatures voltage will be produced according to the temperature variation. This principle is made use in the Thermo Electric Thermometers.

Vapour Pressure Thermometer

Vapour Pressure Thermometer is the thermometer which works by using the pressure of vapour. The relation between the vapour and the temperature is utilized in the Vapour Pressure Thermometers.

Units for measuring temperature

Temperature is the content of the substance. Temperature of a substance is proportional to the average kinetic energy of its molecules. Some units are used to express the temperature of an object. These units are used in various thermometers for measuring the temperature accurately. They are:

1. Fahrenheit – Fahrenheit (°F) is one of the units used to measure the temperature. This unit was introduced by the famous scientist Daniel Gabrial Fahrenheit. The unit Fahrenheit is used in many thermometers, for example the unit used Clinical Thermometer is Fahrenheit.

2. Degree Celsius – Degree Celsius (°C) is another unit used to measure the temperature of a substance. Previously this Celsius scale was known as Centigrade. On 1742 Anderse Celsius developed a Centigrade scale thermometer. Its unit was degree Centigrade. Afterward in 1948, this scale was renamed as Celsius scale.

3. Kelvin – Kelvin is another unit to measure the temperature. Kelvin is one of the seven base units in the International System of Units (SI). This unit is symbolized by the letter K. This unit named as Kelvin as an honor to the famous engineer and physicist Lord Kelvin (William Thomson 1st) who lived in 1824 – 1907. Kelvin is the primary unit of measurement in the physical sciences. Kelvin is defined as the 1/273.16 of the thermodynamic temperature of the triple point of the water.

4. Rankine – Rankine is a thermodynamic temperature scale. This unit scale is introduced by the famous engineer and physicist William John Macquorn Rankine. The unit Rankine is assigned by the letter R.


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