Tag: Index
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Permittivity of Free Space
Introduction The permittivity of free space, commonly denoted as , is a fundamental physical constant that measures the ability of a vacuum to permit electric field lines. It is a crucial parameter in the study of electromagnetism. Definition and Value The permittivity of free space is defined as the ratio of the electric flux density…
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Permeability of Free Space
Introduction The permeability of free space, often denoted as , is a physical constant that describes the amount of magnetic field produced per unit of magnetic current in a vacuum. It is one of the fundamental constants in physics and plays a vital role in the study of electromagnetism. Definition and Value The permeability of…
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Photomultiplier Tube
Introduction Photomultiplier tubes (PMTs) are a type of vacuum tube used to detect and amplify signals from individual photons. PMTs are known for their high sensitivity to light, fast response, and large amplification factors. Structure of a Photomultiplier Tube A PMT typically consists of three main components: Working Principle When a photon strikes the photocathode,…
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Dirac Sea
Introduction The Dirac Sea is a theoretical model of the vacuum as an infinite sea of particles with negative energy. It was first postulated by the British physicist Paul Dirac in 1930 to explain the behavior of electrons in relation to his relativistic quantum mechanical wave equation, known as the Dirac equation. The Dirac Equation…
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Hartman Effect
Introduction The Hartman Effect is a quantum mechanical phenomenon in which the tunneling time for a particle to pass through a potential barrier becomes independent of the barrier’s width when the width is sufficiently large. Named after Thomas Hartman, who first described it in 1962, this effect appears to violate the principle of causality because…
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Gouy Phase
Introduction The Gouy phase is a phase shift that occurs for a beam of light when it propagates through a focusing or defocusing element, like a lens. This phase shift, named after the French scientist Léon Gouy, is an essential aspect of Gaussian beams and wave optics. Gaussian Beams A Gaussian beam is a beam…
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Gluons
Introduction Gluons are elementary particles that mediate the strong interaction, one of the four fundamental forces of nature. They are the force carriers of the strong nuclear force, much like photons are for the electromagnetic force. Properties of Gluons Gluons are bosons, particles with integer spin, and they possess a property known as color charge.…
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Ginzburg-Landau Theory
Introduction The Ginzburg-Landau (GL) theory, named after physicists Vitaly Ginzburg and Lev Landau, is a phenomenological theory that describes superconductivity and superfluidity. It was originally developed to explain the behavior of superconductors near their critical temperature. Ginzburg-Landau Free Energy The GL theory is based on the concept of a complex order parameter , which characterizes…
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d’Alembert’s Principle
Introduction D’Alembert’s principle, named after French mathematician and physicist Jean le Rond d’Alembert, is a fundamental concept in classical mechanics. This principle extends the Newtonian mechanics to systems with constraints and allows the derivation of the equations of motion for complex systems in a generalized and systematic way. Basic Statement of d’Alembert’s Principle D’Alembert’s principle…