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A device used to measure the temperature of gaseous, liquid or solid matter or of a chemical reaction such as fire.
Temperature measurement is important to a wide range of activities, including industry, scientific research, and health care. In health care, thermometers are used to measure the temperature of the human body.
They include the following types:
1. Oral thermometers (those placed under the tongue)
2. Rectal thermometers (those placed within the rectum)
3. Multi-purpose thermometers (those that can be placed under the tongue, in the rectum or under the armpit)
4. Eardrum thermometers (those placed inside the ear).
5. Basal thermometers (highly sensitive thermometers placed under the tongue or in the rectum to measure slight temperature changes indicating that ovulation has taken place in a woman).
When the liquid is heated it expands into a narrow tube that has been calibrated to indicate the temperature.
Temperature can be recorded in Celsius, Farenheit, or Kelvin, therefore, it is important to note which scale the thermometer is calibrated for.
Analog thermometer
BASIC PRINCIPLE:
The basic principal for all thermometers is thermal expansion. In mercury or alcohol based thermometers, the temperature was measured on the basis of expansion.
BASIC PRINCIPLE:
The basic principle is When the Sensor which is located at the tip of the thermometer heats up and its resistance changes.
A small current passed through the sensor (small so that it does not itself cause warming) and this produces a voltage drop across the sensor.
The voltage drop is thus dependent upon the temperature.
In the best sensors, this voltage drop would ideally be a linear one, but in some semi-conductor sensors, it tends to be non-linear and has to be compensated for. The voltage across the sensor is then amplified and fed to an analog to digital converter.
The digital signal is then decoded into that required by the LCD or LED display.
There are two types of principle which can be described as follows:
Pressure type thermometer principle
• According to law, namely certain liquid expanding quality liquid, in its volume, under the condition of liquid pressure and temperature is linear. Gas, steam pressure and temperature are a certain function relation, and therefore the pressure gauge ear thermometer should be uniform type quintiles.
• Pressure type thermometer is by filling inductive medium temperature of temperature bag, transmitting pressure components (capillary) and pressure sensitive components (spring tubes) composition. Infrared measuring temperature meter principle
• any object can have infrared ray radiation, it represents the temperature of the objects
• . The higher the temperature radiation is bigger. With infrared receiver for sensors which is then given to the digital filter and amplified by amplifiers which calculates showing the reading of temperature.
• Infrared temperature-measuring plan by optical system, photoelectric detector, signal amplifier and signal processing.
• Display output components. Optical system gathering its field of view of the target ir radiation energy, infrared energy focus on the photodetector it converted to the corresponding signal, then through this signal conversion into target value being measured.
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