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J. C. Maxwell
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish physicist and mathematician who was responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and light as different manifestations of the same phenomenon. Maxwell's equations for electromagnetism achieved the second great unification in physics, where the first one had been realised by Isaac Newton. Maxwell was also key in the creation of statistical mechanics. With the publication of "A Dynamical Theory of the Electromagnetic Field" in 1865, Maxwell demonstrated that electric and magnetic fields travel through space as waves moving at the speed of light. He proposed that light is an undulation in the same medium that is the cause of electric and magnetic phenomena. (This article accompanied an 8 December 1864 presentation by Maxwell to the Royal Society. His statement that "light and magnetism are affections of the same substanc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edinburgh
Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh had a population of in , making it the List of towns and cities in Scotland by population, second-most populous city in Scotland and the List of cities in the United Kingdom, seventh-most populous in the United Kingdom. The Functional urban area, wider metropolitan area had a population of 912,490 in the same year. Recognised as the capital of Scotland since at least the 15th century, Edinburgh is the seat of the Scottish Government, the Scottish Parliament, the Courts of Scotland, highest courts in Scotland, and the Palace of Holyroodhouse, the official residence of the Monarchy of the United Kingdom, British monarch in Scotland. It is also the annual venue of the General Assembly of the Church of Scotland. The city has long been a cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinetic Theory Of Gases
The kinetic theory of gases is a simple classical model of the thermodynamic behavior of gases. Its introduction allowed many principal concepts of thermodynamics to be established. It treats a gas as composed of numerous particles, too small to be seen with a microscope, in constant, random motion. These particles are now known to be the atoms or molecules of the gas. The kinetic theory of gases uses their collisions with each other and with the walls of their container to explain the relationship between the macroscopic properties of gases, such as volume, pressure, and temperature, as well as transport properties such as viscosity, thermal conductivity and mass diffusivity. The basic version of the model describes an ideal gas. It treats the collisions as perfectly elastic and as the only interaction between the particles, which are additionally assumed to be much smaller than their average distance apart. Due to the time reversibility of microscopic dynamics ( microsco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Additive Color
Additive color or additive mixing is a property of a color model that predicts the appearance of colors made by coincident component lights, i.e. the perceived color can be predicted by summing the numeric representations of the component colors. Modern formulations of Grassmann's laws describe the additivity in the color perception of light mixtures in terms of algebraic equations. Additive color predicts perception and not any sort of change in the photons of light themselves. These predictions are only applicable in the limited scope of color matching experiments where viewers match small patches of uniform color isolated against a gray or black background. Additive color models are applied in the design and testing of electronic displays that are used to render realistic images containing diverse sets of color using phosphors that emit light of a limited set of primary colors. Examination with a sufficiently powerful magnifying lens will reveal that each pixel in CRT, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fovea Centralis
The ''fovea centralis'' is a small, central pit composed of closely packed Cone cell, cones in the eye. It is located in the center of the ''macula lutea'' of the retina. The ''fovea'' is responsible for sharp central visual perception, vision (also called foveal vision), which is necessary in humans for activities for which visual detail is of primary importance, such as reading (activity), reading and driving. The fovea is surrounded by the ''parafovea'' belt and the ''perifovea'' outer region. The ''parafovea'' is the intermediate belt, where the Retinal ganglion cell, ganglion cell layer is composed of more than five layers of cells, as well as the highest density of cones; the ''perifovea'' is the outermost region where the ganglion cell layer contains two to four layers of cells, and is where visual acuity is below the optimum. The ''perifovea'' contains an even more diminished density of cones, having 12 per 100 micrometres versus 50 per 100 micrometres in the most centra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luneburg Lens
A Luneburg lens (original German ''Lüneburg-Linse'') is a spherically symmetric gradient-index lens. A typical Luneburg lens's refractive index ''n'' decreases radially from the center to the outer surface. They can be made for use with electromagnetic radiation from visible light to radio waves. For certain index profiles, the lens will form perfect geometrical images of two given concentric spheres onto each other. There are an infinite number of refractive-index profiles that can produce this effect. The simplest such solution was proposed by Rudolf Luneburg in 1944. Luneburg's solution for the refractive index creates two conjugate foci outside the lens. The solution takes a simple and explicit form if one focal point lies at infinity, and the other on the opposite surface of the lens. J. Brown and A. S. Gutman subsequently proposed solutions which generate one internal focal point and one external focal point. These solutions are not unique; the set of solutions are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell Coil
A Maxwell coil is a device for producing a large volume of almost constant (or constant-gradient) magnetic field. It is named in honour of the Scottish physicist James Clerk Maxwell. A Maxwell coil is an improvement of a Helmholtz coil: in operation it provides an even more uniform magnetic field (than a Helmholtz coil), but at the expense of more material and complexity. Description A constant-field Maxwell coil set consists of three coils oriented on the surface of a virtual sphere. According to Maxwell's original 1873 design: each of the outer coils should be of radius \textstyle \sqrtR , and distance \textstyle \sqrtR from the plane of the central coil of radius R. Maxwell specified the number of windings as 64 for the central coil and 49 for the outer coils. Though Maxwell did not specifically state that current for the coils came from the same source, his work was specifically describing the construction of a sensitive galvanometer designed to detect a single cur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell Bridge
A Maxwell bridge is a modification to a Wheatstone bridge used to measure an unknown inductance (usually of low Q value) in terms of calibrated resistance and inductance or resistance and capacitance. When the calibrated components are a parallel resistor and capacitor, the bridge is known as a Maxwell bridge. It is named for James C. Maxwell, who first described it in 1873. It uses the principle that the positive phase angle of an inductive impedance can be compensated by the negative phase angle of a capacitive impedance when put in the opposite arm and the circuit is at resonance; i.e., no potential difference across the detector (an AC voltmeter or ammeter)) and hence no current flowing through it. The unknown inductance then becomes known in terms of this capacitance. With reference to the picture, in a typical application R_1 and R_4 are known fixed entities, and R_2 and C_2 are known variable entities. R_2 and C_2 are adjusted until the bridge is balanced. R_3 and L_3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell–Wagner–Sillars Polarization
In dielectric spectroscopy, large frequency dependent contributions to the dielectric response, especially at low frequencies, may come from build-ups of charge. This Maxwell–Wagner–Sillars polarization (or often just Maxwell–Wagner polarization), occurs either at inner dielectric boundary layers on a mesoscopic scale, or at the external electrode-sample interface on a macroscopic scale. In both cases this leads to a separation of charges (such as through a depletion layer). The charges are often separated over a considerable distance (relative to the atomic and molecular sizes), and the contribution to dielectric loss can therefore be orders of magnitude larger than the dielectric response due to molecular fluctuations. It is named after the works of James Clerk Maxwell (1891), Karl Willy Wagner (1914) and R. W. Sillars (1937). Occurrences Maxwell-Wagner polarization processes should be taken into account during the investigation of inhomogeneous materials like suspen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Von Mises Yield Criterion
In continuum mechanics, the maximum distortion energy criterion (also von Mises yield criterion) states that yielding of a ductile material begins when the second invariant of deviatoric stress J_2 reaches a critical value. It is a part of plasticity theory that mostly applies to ductile materials, such as some metals. Prior to yield, material response can be assumed to be of a linear elastic, nonlinear elastic, or viscoelastic In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both Viscosity, viscous and Elasticity (physics), elastic characteristics when undergoing deformation (engineering), deformation. Viscous mate ... behavior. In materials science and engineering, the von Mises yield criterion is also formulated in terms of the von Mises stress or equivalent tensile stress, \sigma_\text. This is a scalar value of stress that can be computed from the Cauchy stress tensor. In this case, a material is said to start y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell Material
A Maxwell model is the most simple model viscoelastic material showing properties of a typical liquid. It shows viscous flow on the long timescale, but additional elastic resistance to fast deformations. It is named for James Clerk Maxwell who proposed the model in 1867. It is also known as a Maxwell fluid. A generalization of the scalar relation to a tensor equation lacks motivation from more microscopic models and does not comply with the concept of material objectivity. However, these criteria are fulfilled by the Upper-convected Maxwell model. Definition The Maxwell model is represented by a purely viscosity, viscous damper and a purely Elasticity (physics), elastic spring connected in series, as shown in the diagram. If, instead, we connect these two elements in parallel, we get the generalized model of a solid Kelvin–Voigt material. In Maxwell configuration, under an applied axial stress, the total stress, \sigma_\mathrm and the total strain, \varepsilon_\mathrm ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell's Theorem (geometry)
Maxwell's theorem is the following statement about triangles in the plane. The theorem is named after the physicist James Clerk Maxwell (1831–1879), who proved it in his work on reciprocal figures, which are of importance in statics. References * Daniel Pedoe: ''Geometry: A Comprehensive Course''. Dover, 1970, pp. 35–36, 114–115 * Daniel Pedoe: "On (what should be) a Well-Known Theorem in Geometry." ''The American Mathematical Monthly'', Vol. 74, No. 7 (August – September, 1967), pp. 839–841JSTOR *Dao Thanh Oai, Cao Mai Doai, Quang Trung, Kien Xuong, Thai Binh"Generalizations of some famous classical Euclidean geometry theorems."''International Journal of Computer Discovered Mathematics'', Vol. 1, No. 3, pp. 13–20 External links {{commonscat, Maxwell's theorem ''Maxwell's Theorem'' at cut-the-knot.org Elementary geometry Theorems about triangles James Clerk Maxwell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxwell's Theorem
In probability theory, Maxwell's theorem (known also as Herschel-Maxwell's theorem and Herschel-Maxwell's derivation) states that if the probability distribution of a random vector in \R^n is unchanged by rotations, and if the components are independent, then the components are identically distributed and normally distributed. Equivalent statements If the probability distribution of a vector space, vector-valued random variable ''X'' = ( ''X''1, ..., ''X''''n'' )''T'' is the same as the distribution of ''GX'' for every ''n''×''n'' orthogonal matrix ''G'' and the components are statistical independence, independent, then the components ''X''1, ..., ''X''''n'' are normal distribution, normally distributed with expected value 0 and all have the same variance. This theorem is one of many characterization (mathematics), characterizations of the normal distribution. The only rotationally invariant probability distributions on R''n'' that have independent components are multivariate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
