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Black Body Spectrum Blackbody radiation Blackbody radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and nonreflective body). It has a specific spectrum and intensity that depends only on the body's temperature, which is assumed for the sake of calculations and theory to be uniform and constant.[1][2][3][4] The thermal radiation spontaneously emitted by many ordinary objects can be approximated as blackbody radiation [...More...]  "Black Body Spectrum" on: Wikipedia Yahoo 

Chromaticity Chromaticity Chromaticity is an objective specification of the quality of a color regardless of its luminance. Chromaticity Chromaticity consists of two independent parameters, often specified as hue (h) and colorfulness (s), where the latter is alternatively called saturation, chroma, intensity,[1] or excitation purity.[2][3] This number of parameters follows from trichromacy of vision of most humans, which is assumed by most models in color science.Contents1 Quantitative description 2 See also 3 References 4 External linksQuantitative description[edit] In color science, the white point of an illuminant or of a display is a neutral reference characterized by a chromaticity; all other chromaticities may be defined in relation to this reference using polar coordinates [...More...]  "Chromaticity" on: Wikipedia Yahoo 

Temperature Temperature Temperature is a physical quantity expressing hot and cold. Temperature Temperature is measured with a thermometer, historically calibrated in various temperature scales and units of measurement. The most commonly used scales are the Celsius Celsius scale, denoted in °C (informally, degrees centigrade), the Fahrenheit scale Fahrenheit scale (°F), and the Kelvin Kelvin scale. The kelvin (K) is the unit of temperature in the International System of Units (SI), in which temperature is one of the seven fundamental base quantities. The coldest theoretical temperature is absolute zero, at which the thermal motion of all fundamental particles in matter reaches a minimum. Although classically described as motionless, particles still possess a finite zeropoint energy in the quantum mechanical description [...More...]  "Temperature" on: Wikipedia Yahoo 

Absolute Zero Absolute zero Absolute zero is the lower limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reaches its minimum value, taken as 0. Absolute zero Absolute zero is the point at which the fundamental particles of nature have minimal vibrational motion, retaining only quantum mechanical, zeropoint energyinduced particle motion [...More...]  "Absolute Zero" on: Wikipedia Yahoo 

Spontaneous Process A spontaneous process is the timeevolution of a system in which it releases free energy and it moves to a lower, more thermodynamically stable energy state.[1][2] The sign convention for free energy follows the general convention for thermodynamic measurements, in which a release of free energy from the system corresponds to a negative change in the free energy of the system and a positive change in the free energy of the surroundings. Depending on the nature of the process, the free energy is determined differently [...More...]  "Spontaneous Process" on: Wikipedia Yahoo 

Entropy In statistical mechanics, entropy (usual symbol S) is related to the number of microscopic configurations Ω that a thermodynamic system can have when in a state as specified by some macroscopic variables. Specifically, assuming for simplicity that each of the microscopic configurations is equally probable, the entropy of the system is the natural logarithm of that number of configurations, multiplied by the Boltzmann constant Boltzmann constant kB. Formally, S = k B ln Ω (assuming equiprobable states) . displaystyle S=k_ mathrm B ln Omega text (assuming equiprobable states) . This is consistent with 19thcentury formulas for entropy in terms of heat and temperature, as discussed below [...More...]  "Entropy" on: Wikipedia Yahoo 

Wavelength In physics, the wavelength is the spatial period of a wave—the distance over which the wave's shape repeats,[1][2] and thus the inverse of the spatial frequency. It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns.[3][4] Wavelength Wavelength is commonly designated by the Greek letter Greek letter lambda (λ) [...More...]  "Wavelength" on: Wikipedia Yahoo 

Graphite Graphite Graphite ( /ˈɡræfaɪt/), archaically referred to as plumbago, is a crystalline allotrope of carbon, a semimetal, a native element mineral, and a form of coal.[5] Graphite Graphite is the most stable form of carbon under standard conditions [...More...]  "Graphite" on: Wikipedia Yahoo 

Carbon Black Carbon black Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, with the addition of a small amount of vegetable oil.[citation needed] Carbon black Carbon black is a form of paracrystalline carbon that has a high surfaceareatovolume ratio, albeit lower than that of activated carbon. It is dissimilar to soot in its much higher surfaceareatovolume ratio and significantly lower (negligible and nonbioavailable) PAH (polycyclic aromatic hydrocarbon) content. However, carbon black is widely used as a model compound for diesel soot for diesel oxidation experiments.[1] Carbon black is mainly used as a reinforcing filler in tires and other rubber products [...More...]  "Carbon Black" on: Wikipedia Yahoo 

Draper Point The Draper point is the approximate temperature above which almost all solid materials visibly glow as a result of blackbody radiation. It was established at 977 °F (525 °C, 798 K) by John William Draper in 1847.[1][2][3] Bodies at temperatures just below the Draper point radiate primarily in the infrared range and emit negligible visible light [...More...]  "Draper Point" on: Wikipedia Yahoo 

Radiative Equilibrium Radiative equilibrium is one of the several requirements for thermodynamic equilibrium, but it can occur in the absence of thermodynamic equilibrium [...More...]  "Radiative Equilibrium" on: Wikipedia Yahoo 

Detailed Balance The principle of detailed balance is formulated for kinetic systems which are decomposed into elementary processes (collisions, or steps, or elementary reactions): At equilibrium, each elementary process should be equilibrated by its reverse process.Contents1 History 2 Microscopic background 3 Reversible Markov chains 4 Detailed balance and entropy increase 5 Wegscheider's conditions for the generalized mass action law 6 Dissipation in systems with detailed balance 7 Onsager reciprocal relations Onsager reciprocal relations and detailed balance 8 Semidetailed balance 9 Dissipation in systems with semidetailed balance 10 Detailed balance for systems with irreversible reactions 11 See also 12 ReferencesHistory[edit] The principle of detailed balance was explicitly introduced for collisions by Ludwig Boltzmann [...More...]  "Detailed Balance" on: Wikipedia Yahoo 

Kirchhoff's Law Of Thermal Radiation In heat transfer, Kirchhoff's law of thermal radiation Kirchhoff's law of thermal radiation refers to wavelengthspecific radiative emission and absorption by a material body in thermodynamic equilibrium, including radiative exchange equilibrium. A body at temperature T radiates electromagnetic energy. A perfect black body in thermodynamic equilibrium absorbs all light that strikes it, and radiates energy according to a unique law of radiative emissive power for temperature T, universal for all perfect black bodies. Kirchhoff's law states that:For a body of any arbitrary material emitting and absorbing thermal electromagnetic radiation at every wavelength in thermodynamic equilibrium, the ratio of its emissive power to its dimensionless coefficient of absorption is equal to a universal function only of radiative wavelength and temperature [...More...]  "Kirchhoff's Law Of Thermal Radiation" on: Wikipedia Yahoo 

Hohlraum In radiation thermodynamics, a hohlraum (a nonspecific German word for a "hollow space" or "cavity") is a cavity whose walls are in radiative equilibrium with the radiant energy within the cavity. This idealized cavity can be approximated in practice by making a small perforation in the wall of a hollow container of any opaque material. The radiation escaping through such a perforation will be a good approximation to blackbody radiation at the temperature of the interior of the container.Contents1 Inertial confinement fusion 2 Nuclear weapon design 3 Notes and references 4 External linksInertial confinement fusion[edit]Mockup of a goldplated hohlraum designed for use in the National Ignition FacilityThe indirect drive approach to inertial confinement fusion is as follows; the fusion fuel capsule is held inside a cylindrical hohlraum. The radiation source (e.g., laser) is pointed at the interior of the hohlraum rather than at the capsule itself [...More...]  "Hohlraum" on: Wikipedia Yahoo 

Power Spectral Density The power spectrum S x x ( f ) displaystyle S_ xx (f) of a time series x ( t ) displaystyle x(t) describes the distribution of power into frequency components composing that signal.[1] According to Fourier analysis Fourier analysis any physical signal can be decomposed into a number of discrete frequencies, or a spectrum of frequencies over a continuous range. The statistical average of a certain signal or sort of signal (including noise) as analyzed in terms of its frequency content, is called its spectrum. When the energy of the signal is concentrated around a finite time interval, especially if its total energy is finite, one may compute the energy spectral density [...More...]  "Power Spectral Density" on: Wikipedia Yahoo 