Thermodynamic temperature
... at 273.16K as the fundamental fixing point. Other scales kinetic energy remains in a substance at absolute zero (see have been in use historically. The Rankine scale, using Thermal energy at absolute zero, below). the degree Fahrenheit as its unit interval, is still in use as part of the English Engi ...
... at 273.16K as the fundamental fixing point. Other scales kinetic energy remains in a substance at absolute zero (see have been in use historically. The Rankine scale, using Thermal energy at absolute zero, below). the degree Fahrenheit as its unit interval, is still in use as part of the English Engi ...
6. Macroscopic equilibrium states and state variables (Hiroshi
... is a macroscopic quantity that we measure using a thermometer. Below we will explain what we mean by this definition. As the notion of temperature is derived from a notion of “equilibrium state,” we must first carefully define the equilibrium state. Equilibrium states of an isolated system with a co ...
... is a macroscopic quantity that we measure using a thermometer. Below we will explain what we mean by this definition. As the notion of temperature is derived from a notion of “equilibrium state,” we must first carefully define the equilibrium state. Equilibrium states of an isolated system with a co ...
Basic Concepts and Definitions
... The gas in a cylinder is assumed to contain a large number of molecules each having same mass and velocity independent of each other. In order to describe the thermodynamic system in view of microscopic approach, it is necessary to describe the position of each and every molecule which is very compl ...
... The gas in a cylinder is assumed to contain a large number of molecules each having same mass and velocity independent of each other. In order to describe the thermodynamic system in view of microscopic approach, it is necessary to describe the position of each and every molecule which is very compl ...
On the Foundations of Classical Thermodynamics, and the Tolman
... into the colder surroundings until the body has cooled down and the heat gradient has vanished. After uniformity of hotness has been established, no more changes will occur, and at this point the body is said to have reached thermal equilibrium with its surroundings. The meaning of the term ”hotness ...
... into the colder surroundings until the body has cooled down and the heat gradient has vanished. After uniformity of hotness has been established, no more changes will occur, and at this point the body is said to have reached thermal equilibrium with its surroundings. The meaning of the term ”hotness ...
Black-body radiation
Black-body radiation is the type of electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and non-reflective body) held at constant, uniform temperature. The radiation has a specific spectrum and intensity that depends only on the temperature of the body.The thermal radiation spontaneously emitted by many ordinary objects can be approximated as blackbody radiation. A perfectly insulated enclosure that is in thermal equilibrium internally contains black-body radiation and will emit it through a hole made in its wall, provided the hole is small enough to have negligible effect upon the equilibrium.A black-body at room temperature appears black, as most of the energy it radiates is infra-red and cannot be perceived by the human eye. Because the human eye cannot perceive color at very low light intensities, a black body, viewed in the dark at the lowest just faintly visible temperature, subjectively appears grey (but only because the human eye is sensitive only to black and white at very low intensities - in reality, the frequency of the light in the visible range would still be red, although the intensity would be too low to discern as red), even though its objective physical spectrum peaks in the infrared range. When it becomes a little hotter, it appears dull red. As its temperature increases further it eventually becomes blindingly brilliant blue-white.Although planets and stars are neither in thermal equilibrium with their surroundings nor perfect black bodies, black-body radiation is used as a first approximation for the energy they emit.Black holes are near-perfect black bodies, in the sense that they absorb all the radiation that falls on them. It has been proposed that they emit black-body radiation (called Hawking radiation), with a temperature that depends on the mass of the black hole.The term black body was introduced by Gustav Kirchhoff in 1860. When used as a compound adjective, the term is typically written as hyphenated, for example, black-body radiation, but sometimes also as one word, as in blackbody radiation. Black-body radiation is also called complete radiation or temperature radiation or thermal radiation.