Thermomètres

Thermomètres are instruments used to measure temperature. The most common type relies on the principle of thermal expansion, where a substance changes its volume in response to temperature fluctuations. Traditionally, liquid-in-glass thermometers are widely recognized. These consist of a sealed glass tube containing a liquid, typically mercury or colored alcohol, within a bulb at one end. As the temperature increases, the liquid expands and rises up the calibrated scale etched onto the glass. Conversely, a decrease in temperature causes the liquid to contract and fall.

Digital thermometers utilize electronic sensors to detect temperature. Thermistors and thermocouples are common types of electronic temperature sensors. Thermistors are resistors whose resistance changes significantly with temperature. Thermocouples generate a voltage that is proportional to the temperature difference between two dissimilar metals. These electronic signals are then processed and displayed as a numerical temperature reading on a screen. Infrared thermometers, another electronic type, measure the thermal radiation emitted by an object without direct contact. This makes them useful for measuring the temperature of distant or moving objects, or in situations where contact is undesirable. Thermomètres are essential tools in various fields, including meteorology, medicine, industry, and scientific research.