“Oh! Your body is hot let me check your temperature.” Someone takes out a thermometer put it in your mouth and get to know the body temperature. A sudden question flashes your mind – what is this thermometer all about? How can it read the body temperature?

Everyone has seen thermometer. It has two parts: the temperature sensor (some physical changes with increasing or decreasing temperature) and the scale (which converts the physical change into

a value). It is used to measure temperature (hotness or coldness) of body. This device is based on various principles. It contains mercury. Mercury is a liquid metal which changes its physical state with change in temperature. These are calibrated to a constant-volume gas thermometer. Calibration is the process of putting a scale to a thermometer. There are various methods to it. Care should be taken for accuracy. Thermometers can be either electrical or mechanical and cannot be separated from the system, they control.

It finds its application in:

• Telling us the hotness and coldness of environment.

• Telling us the food temperature in kitchen.

• Telling us the temperature of human body in different units, say, Fahrenheit or Celsius scales.

• Keeping the temperature of the oven and refrigerator constant.

• Letting us know the off and on time for furnaces.

Digital Hygro thermometer provides room temperature and relative humidity, the sensors for which are in-built. It is used in food industry as it is more accurate and quick response-time. It is necessary to ensure safety of meat, poultry and egg products. These should be cooked at right temperatures so that harmful microorganisms are destroyed.
Automatic thermometers have different ranges and scales and can also display it. It can also automatically switch-off and is used in vaccine shipments.

Deformation thermometers are used in household temperature controls. It uses bimetal and gets deformed when heated.

Aircraft uses electrical thermometers and measures engine-cylinder temperatures. It depends on the predictable change of electrical resistance in metals or semi-conductors. Current flows through a circuit with galvanometer inserted in it.

Diode thermometers are used to measure the temperature when power transistors are used.

Hence we see that thermometers play a vital role in our day to day life, from knowing the temperature of a particular thing to maintaining it at the standards. So next time you see a thermometer, take it in your hand and see how it works. Use methods to maintain your body temperature as well as environment temperature to be happy.

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