Author: Tru Physics
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Unruh Effect
Introduction The Unruh effect is a theoretical prediction in quantum field theory and is one of the results showing the deep connections between quantum physics, thermodynamics, and relativity. Proposed by William G. Unruh in 1976, it suggests that an accelerating observer will be in a thermal state – in other words, they will observe a…
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Neutrons
Introduction Neutrons are subatomic particles that, along with protons, make up atomic nuclei. Neutrons are neutral, carrying no net electric charge. Basic Properties Neutrons are slightly more massive than protons. The mass of a neutron is approximately: Since neutrons carry no net electric charge, their electric charge is 0. Structure and Composition Neutrons are also…
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Protons
Introduction Protons are subatomic particles with positive electric charge. They reside with neutrons within the atomic nucleus, with electrons “orbiting” around them. Basic Properties The proton carries a positive charge, denoted as , where is the elementary charge. The value of the elementary charge is: The mass of a proton is significantly greater than that…
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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…