3. What is Thermometer? A thermometer is Greek word. It is the combination of two words. Thermo Warm Meter to measure A thermometer is an instrument that measures the temperature of a system in a quantitative way.

4. Early history Galileo invented the first thermometer in the 1600s. The exact year is not known, but historians estimate that it was in 1593. He was a famous Italian Mathematician and Scientist whose inventions and mathematical theories are still in use today. The basic principle behind a thermometer, the expansion of air by heat and contraction by cold. Though Galileo is often said to be the inventor of the thermometer.

5. Principle It is a device that measures temperature or temperature gradient using a variety of different principles. A thermometer has two important elements: the temperature sensor (e.g. the bulb on a mercury thermometer in which some physical change occurs with temperature, plus some means of converting this physical change into a value (e.g. the scale on a mercury thermometer).

8. secondary thermometer Secondary thermometers are most widely used because of their convenience. Also, they are often much more sensitive than primary ones. For secondary thermometers knowledge of the measured property is not sufficient to allow direct calculation of temperature. They have to be calibrated against a primary thermometer at least at one temperature or at a number of fixed temperatures. Such fixed points, for example, triple points and superconducting transitions, occur reproducibly at the same temperature.

10. Medical thermometer

11. Beckmann differential thermometer

12. Bi-metal mechanical thermometer

13. Mercury-in-glass thermometer

15. Medical thermometer Medical thermometers are used for measuring human body temperature, with the tip of the thermometer being inserted either into the mouth (oral temperature), under the armpit (axillary temperature)

16. Beckmann differential thermometer A Beckmann thermometer is a device used to measure small differences of temperature, but not absolute temperature values. It was invented by Ernst Otto Beckmann (1853 – 1923), a German chemist.

17. Bi-Metal mechanical Thermometer A bimetallic strip is used to convert a temperature change into mechanical displacement

18. Mercury-in-glass thermometer mercury-in-glass thermometer, invented by German physicist Daniel Gabriel Fahrenheit, is a thermometer consisting of mercury in a glass tube. Calibrated marks on the tube allow the temperature to be read by the length of the mercury within the tube, which varies according to the heat given to it. To increase the sensitivity.

19. Alcohol thermometer It is also the earliest efficient modern-style instrument of temperature measurement, being first invented in 1654. The Alcohol thermometer is an alternative to the Mercury-in-glass thermometer, and functions in a similar way.

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