Temperature to broil steak суббота 21 январь 2023 г. Moon times precise to the second. Exclusive calendar templates for PDF Calendar.
On this Wikipedia the language links are at the top of the page across from the article title. This article is about the physical quantity. Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. This section needs additional citations for verification.
Please help improve this article by adding citations to reliable sources. Temperature scales need two values for definition: the point chosen as zero degrees and the magnitudes of the incremental unit of temperature. It was called a centigrade scale because of the 100-degree interval. The Fahrenheit scale is in common use in the United States.
At the absolute zero of temperature, no energy can be removed from matter as heat, a fact expressed in the third law of thermodynamics. Since May, 2019, the kelvin has been defined through particle kinetic theory, and statistical mechanics. Since May 2019, the magnitude of the kelvin is defined in relation to microscopic phenomena, characterized in terms of statistical mechanics. Historically, the temperature of the triple point of water was defined as exactly 273. Today it is an empirically measured quantity. There are various kinds of temperature scale. It may be convenient to classify them as empirically and theoretically based.
Empirical temperature scales are historically older, while theoretically based scales arose in the middle of the nineteenth century. Empirically based temperature scales rely directly on measurements of simple macroscopic physical properties of materials. For example, the length of a column of mercury, confined in a glass-walled capillary tube, is dependent largely on temperature and is the basis of the very useful mercury-in-glass thermometer. Such scales are valid only within convenient ranges of temperature. In spite of these limitations, most generally used practical thermometers are of the empirically based kind. Especially, it was used for calorimetry, which contributed greatly to the discovery of thermodynamics. Nevertheless, empirical thermometry has serious drawbacks when judged as a basis for theoretical physics.
Theoretically based temperature scales are based directly on theoretical arguments, especially those of kinetic theory and thermodynamics. They are more or less ideally realized in practically feasible physical devices and materials. Theoretically based temperature scales are used to provide calibrating standards for practical empirically based thermometers. In physics, the internationally agreed conventional temperature scale is called the Kelvin scale. Apart from the absolute zero of temperature, the Kelvin temperature of a body in a state of internal thermodynamic equilibrium is defined by measurements of suitably chosen of its physical properties, such as have precisely known theoretical explanations in terms of the Boltzmann constant.