 Temperature measurement

Temperature measurement infers temperature from a reproducible physical response of a thermometer. Examples include a liquid column's thermal expansion, a sensor's electrical resistance and the thermal radiation emitted by a surface. Calibration connects the response to specified reference temperatures or a physical temperature scale.

A contact probe must exchange heat with the object, so its reading depends on time and thermal coupling. A small probe can respond rapidly, while a large probe can noticeably disturb a small sample. Heat conducted along the probe stem and electrical self-heating can shift the reading away from the object's undisturbed temperature.

A useful immersion experiment is to insert a probe progressively farther into a well-stirred bath and wait after each movement. A reading that changes with immersion depth reveals a heat-leak or equilibration problem. Repeating a calibration does not by itself remove such measurement-condition errors.

Temperature measurement is the process of determining the degree of heat or coldness of an object or environment. It is an essential parameter in various fields, including meteorology, medicine, engineering, and environmental science. Temperature is typically measured using various types of instruments known as thermometers, which can operate on different principles.