hmérsékletmérk

Hmérsékletmérk is the Hungarian word for thermometer. A thermometer is a device that measures temperature or the temperature gradient used in a system. It is a common household item used to check for fever, and in industrial settings, it is used for precise temperature control.

The most common type of thermometer in use today is the mercury-in-glass thermometer, although these are being replaced by digital thermometers due to concerns about mercury. Other types include alcohol thermometers, bimetallic strip thermometers, and infrared thermometers.

The principle behind many thermometers is thermal expansion. Most substances expand when heated and contract when cooled. In a mercury or alcohol thermometer, the liquid inside a glass tube expands or contracts, and this movement is calibrated against a temperature scale. A bimetallic strip thermometer uses two different metals with different expansion rates bonded together. When heated, the strip bends, and this bending is used to indicate temperature. Infrared thermometers measure the thermal radiation emitted by an object, allowing for non-contact temperature measurement.

The development of the thermometer dates back to the late 16th and early 17th centuries. Galileo Galilei is often credited with inventing an early form of thermometer, though it lacked a standardized scale. Later, scientists like Daniel Gabriel Fahrenheit and Anders Celsius developed more accurate and widely adopted temperature scales, which are still in use today. The Celsius scale is primarily used in most of the world, while the Fahrenheit scale is still common in the United States.