There must be no one who doesn’t know what is a thermometer! We all get thermometer used on us as infants and understand the importance of the device called thermometer, of vital medical use even if we are not doctors or in the medical profession.
A definition of thermometer is simple a device that is used to measure temperature or a temperature gradient.
What is a thermometer made up of?
- A sensor – bulb of mercury in a glass thermometer causing physical change to indicate temperature.
- Means of converting the visible physical change and relating to a numeric value – a scale marked in a glass thermometer.
Other than its medicinal use a thermometer is widely used to regulate and control various processes in the industry – to study things like weather or for areas of scientific research. Without the knowledge of temperature many a devices would be redundant and insignificant.
Thermometers across the world operate on the principles – of thermal expansion that occurs in solids or liquids when they succumb to temperature changes and on the change in pressure of a gas under heat or cold conditions.
The infrared energy emitted by an object is measured by radiation-type thermometers. This is done by measurement of temperature yet without any contact.
Metals normally remain solid in room temperatures and are good conductors of heat. Mercury is one and only that is in liquid state when in room temperature and shows a high coefficient of expansion. Which means that even the slightest change in any temperature effects the state of mercury and suitable for a thermometer.
As a result mercury and alcohol are used in the device too check temperature called thermometer.
It is amazing to know that as early as two thousand years ago Greek philosophers knew the about the principles of the thermometer. Over the period of time the modern use of thermometer has evolved from thermoscope to an additional scale that was installed in the early 17th century. The standardization occurred in the 17th and 18th centuries.
Temperature is to measure the degree of hotness – and every thermometer has a different reading not comparable unless they follow the same scale. The current official thermometer scale is called International Temperature Scale of 1990.
Thermometers for Medical use:
- Ear thermometers – are infra red thermometer.
- Forehead thermometers are made of a liquid and crystal.
- Oral and rectal thermometers are made of mercury and are overtaken by thermistors that have a digital readout.
A number of thermometric techniques have been used since time immemorial – for example Galileo thermometer to thermal imaging.
Food and Safety – Thermometers are very useful to monitor the food and safety because the safety of the food is lost if subjected to high temperatures and are prone to bacterial growth that cause food borne illness.
Maintaining temperatures in food especially when it is served under heat lamps or hot water baths. Even while cooking the temperature at which the food is cooked determines if the food is cooked. There are meat thermometers used to aid in cooking and in preventing over cooking.
Sometimes Candy thermometers are used to achieve a specific water content present in a sugar solution when it in its boiling temperature.