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Planck's Relation
The Planck relationFrench & Taylor (1978), pp. 24, 55.Cohen-Tannoudji, Diu & Laloë (1973/1977), pp. 10–11. (referred to as Planck's energy–frequency relation,Schwinger (2001), p. 203. the Planck relation, Planck equation, and Planck formula, though the latter might also refer to Planck's law) is a fundamental equation in quantum mechanics which states that the energy of a photon, , known as photon energy, is proportional to its frequency, : E = h \nu The constant of proportionality, , is known as the Planck constant. Several equivalent forms of the relation exist, including in terms of angular frequency, : E = \hbar \omega where \hbar = h / 2 \pi. The relation accounts for the quantized nature of light and plays a key role in understanding phenomena such as the photoelectric effect and black-body radiation (where the related Planck postulate can be used to derive Planck's law). Spectral forms Light can be characterized using several spectral quantities, such as frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planck's Law
In physics, Planck's law describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature , when there is no net flow of matter or energy between the body and its environment. At the end of the 19th century, physicists were unable to explain why the observed spectrum of black-body radiation, which by then had been accurately measured, diverged significantly at higher frequencies from that predicted by existing theories. In 1900, German physicist Max Planck heuristically derived a formula for the observed spectrum by assuming that a hypothetical electrically charged oscillator in a cavity that contained black-body radiation could only change its energy in a minimal increment, , that was proportional to the frequency of its associated electromagnetic wave. This resolved the problem of the ultraviolet catastrophe predicted by classical physics. This discovery was a pioneering insight of modern physics and is of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reduced Planck Constant
The Planck constant, or Planck's constant, is a fundamental physical constant of foundational importance in quantum mechanics. The constant gives the relationship between the energy of a photon and its frequency, and by the mass-energy equivalence, the relationship between mass and frequency. Specifically, a photon's energy is equal to its frequency multiplied by the Planck constant. The constant is generally denoted by h. The reduced Planck constant, or Dirac constant, equal to the constant divided by 2 \pi, is denoted by \hbar. In metrology it is used, together with other constants, to define the kilogram, the SI unit of mass. The SI units are defined in such a way that, when the Planck constant is expressed in SI units, it has the exact value The constant was first postulated by Max Planck in 1900 as part of a solution to the ultraviolet catastrophe. At the end of the 19th century, accurate measurements of the spectrum of black body radiation existed, but the distribu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alfred Landé
Alfred Landé (13 December 1888 – 30 October 1976) was a German-American physicist known for his contributions to quantum theory. He is responsible for the Landé g-factor and an explanation of the Zeeman effect. Life and achievements Alfred Landé was born on 13 December 1888 in Elberfeld, Rhineland, Germany, today part of the city of Wuppertal. In 1913 Landé was sent by Arnold Sommerfeld, his thesis advisor at the University of Munich, to be a special assistant for physics to David Hilbert at the University of Göttingen, to replace Paul Peter Ewald, whom Sommerfeld had sent to the same position in 1912. There, Landé also came in close contact with Max Born. In physics, it was the era of the Bohr atom model. The leaders of Göttingen science included many greats that Landé was to come in contact with including Hilbert, Edmund Landau, Carl Runge and Ludwig Prandtl (the noted aerodynamics theoreticist). Also Niels Bohr and Hendrik Lorentz visited Göttingen frequ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edwin F
The name Edwin means "rich friend". It comes from the Old English elements "ead" (rich, blessed) and "ƿine" (friend). The original Anglo-Saxon form is Eadƿine, which is also found for Anglo-Saxon figures. People * Edwin of Northumbria (died 632 or 633), King of Northumbria and Christian saint * Edwin (son of Edward the Elder) (died 933) * Eadwine of Sussex (died 982), King of Sussex * Eadwine of Abingdon (died 990), Abbot of Abingdon * Edwin, Earl of Mercia (died 1071), brother-in-law of Harold Godwinson (Harold II) *Edwin (director) (born 1978), Indonesian filmmaker * Edwin (musician) (born 1968), Canadian musician * Edwin Abeygunasekera, Sri Lankan Sinhala politician, member of the 1st and 2nd State Council of Ceylon * Edwin Ariyadasa (1922-2021), Sri Lankan Sinhala journalist * Edwin Austin Abbey (1852–1911) British artist * Edwin Eugene Aldrin (born 1930), although he changed it to Buzz Aldrin, American astronaut * Edwin Howard Armstrong (1890–1954), American in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anthony French
Anthony Philip French (November 19, 1920 – February 3, 2017) was a British professor of physics at the Massachusetts Institute of Technology. He was born in Brighton, England. French was a graduate of Cambridge University, receiving his B.A. in 1942 and Ph.D. in 1948, both in physics. In 1942, he began working on the British effort to build an atomic bomb (codenamed Tube Alloys) at the Cavendish Laboratory. By 1944, Tube Alloys had been merged with the American Manhattan Project and he was sent to Los Alamos. When the war ended, he returned to the United Kingdom, where he spent a couple of years at the newly formed Atomic Energy Research Establishment. He later joined the faculty at Cambridge, where he conducted his research at Cavendish and became a Fellow and Director of Studies in Natural Sciences at Pembroke College, Cambridge. In 1955, French arrived at the University of South Carolina, where he was made chairman of the physics department. He left South Caroli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Claude Cohen-Tannoudji
Claude Cohen-Tannoudji (; born 1 April 1933) is a French physicist. He shared the 1997 Nobel Prize in Physics with Steven Chu and William Daniel Phillips for research in methods of laser cooling and trapping atoms. Currently he is still an active researcher, working at the École normale supérieure (Paris). Early life Cohen-Tannoudji was born in Constantine, French Algeria, to Algerian Jewish parents Abraham Cohen-Tannoudji and Sarah Sebbah. When describing his origins Cohen-Tannoudji said: "My family, originally from Tangier, settled in Tunisia and then in Algeria in the 16th century after having fled Spain during the Inquisition. In fact, our name, Cohen-Tannoudji, means simply the Cohen family from Tangiers. The Algerian Jews obtained the French citizenship in 1870 after Algeria became a French colony in 1830." After finishing secondary school in Algiers in 1953, Cohen-Tannoudji left for Paris to attend the École Normale Supérieure. His professors included Henri Cartan, L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compton Wavelength
The Compton wavelength is a quantum mechanical property of a particle. The Compton wavelength of a particle is equal to the wavelength of a photon whose energy is the same as the rest energy of that particle (see mass–energy equivalence). It was introduced by Arthur Compton in 1923 in his explanation of the scattering of photons by electrons (a process known as Compton scattering). The standard Compton wavelength of a particle is given by \lambda = \frac, while its frequency is given by f = \frac, where is the Planck constant, is the particle's proper mass, and is the speed of light. The significance of this formula is shown in the derivation of the Compton shift formula. It is equivalent to the de Broglie wavelength with v = \frac . The CODATA 2018 value for the Compton wavelength of the electron is . Other particles have different Compton wavelengths. Reduced Compton wavelength The reduced Compton wavelength (barred lambda) is defined as the Compton wavelength di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy Level
A quantum mechanical system or particle that is bound—that is, confined spatially—can only take on certain discrete values of energy, called energy levels. This contrasts with classical particles, which can have any amount of energy. The term is commonly used for the energy levels of the electrons in atoms, ions, or molecules, which are bound by the electric field of the nucleus, but can also refer to energy levels of nuclei or vibrational or rotational energy levels in molecules. The energy spectrum of a system with such discrete energy levels is said to be quantized. In chemistry and atomic physics, an electron shell, or principal energy level, may be thought of as the orbit of one or more electrons around an atom's nucleus. The closest shell to the nucleus is called the " shell" (also called "K shell"), followed by the " shell" (or "L shell"), then the " shell" (or "M shell"), and so on farther and farther from the nucleus. The shells correspond with the principal qu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Transition
A quantum jump is the abrupt transition of a quantum system (atom, molecule, atomic nucleus) from one quantum state to another, from one energy level to another. When the system absorbs energy, there is a transition to a higher energy level (excitation); when the system loses energy, there is a transition to a lower energy level. The concept was introduced by Niels Bohr, in his 1913 Bohr model. A quantum jump is a phenomenon that is peculiar to quantum systems and distinguishes them from classical systems, where any transitions are performed gradually. In quantum mechanics, such jumps are associated with the non-unitary evolution of a quantum-mechanical system during measurement. A quantum jump can be accompanied by the emission or absorption of photons; energy transfer during a quantum jump can also occur by non-radiative resonant energy transfer or in collisions with other particles. In modern physics, the concept of a quantum jump is rarely used; as a rule scientists spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Wave Vector
In physics, a wave vector (or wavevector) is a vector used in describing a wave, with a typical unit being cycle per metre. It has a magnitude and direction. Its magnitude is the wavenumber of the wave (inversely proportional to the wavelength), and its direction is perpendicular to the wavefront. In isotropic media, this is also the direction of wave propagation. A closely related vector is the angular wave vector (or angular wavevector), with a typical unit being radian per metre. The wave vector and angular wave vector are related by a fixed constant of proportionality, 2π radians per cycle. It is common in several fields of physics to refer to the angular wave vector simply as the ''wave vector'', in contrast to, for example, crystallography. It is also common to use the symbol ''k'' for whichever is in use. In the context of special relativity, ''wave vector'' can refer to a four-vector, in which the (angular) wave vector and (angular) frequency are combined. Def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vector (physics)
In mathematics, physics, and engineering, a Euclidean vector or simply a vector (sometimes called a geometric vector or spatial vector) is a geometric object that has magnitude (or length) and direction. Vectors can be added to other vectors according to vector algebra. A Euclidean vector is frequently represented by a '' directed line segment'', or graphically as an arrow connecting an ''initial point'' ''A'' with a ''terminal point'' ''B'', and denoted by \overrightarrow . A vector is what is needed to "carry" the point ''A'' to the point ''B''; the Latin word ''vector'' means "carrier". It was first used by 18th century astronomers investigating planetary revolution around the Sun. The magnitude of the vector is the distance between the two points, and the direction refers to the direction of displacement from ''A'' to ''B''. Many algebraic operations on real numbers such as addition, subtraction, multiplication, and negation have close analogues for vectors, operations w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wave–particle Duality
Wave–particle duality is the concept in quantum mechanics that every particle or quantum entity may be described as either a particle or a wave. It expresses the inability of the classical concepts "particle" or "wave" to fully describe the behaviour of quantum-scale objects. As Albert Einstein wrote: Through the work of Max Planck, Albert Einstein, Louis de Broglie, Arthur Compton, Niels Bohr, Erwin Schrödinger and many others, current scientific theory holds that all particles exhibit a wave nature and vice versa. This phenomenon has been verified not only for elementary particles, but also for compound particles like atoms and even molecules. For macroscopic particles, because of their extremely short wavelengths, wave properties usually cannot be detected. Although the use of the wave–particle duality has worked well in physics, the meaning or interpretation has not been satisfactorily resolved; see interpretations of quantum mechanics. Bohr regarded the "duality ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
