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BCS Theory of Superconductivity

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  Introduction: Bardeen-Cooper-Schrieffer theory (BCS theory) is the first microscopic theory of superconductivity. Cooper had discovered that electrons are in pairs in a superconductor and named as Cooper pairs. The theory describes superconductivity as an effect caused by the condensation (I will talk briefly about condensation later in this article) of the Cooper pair. The motion of all the Cooper pairs within a single superconductor constitutes a system that functions as a single entity. Applying an electrical voltage to the superconductor causes all Cooper pairs to move, forming a current. Even in the absence of voltage, the current flow continues indefinitely. The reason is that the Cooper pairs encounter no opposition inside the conductor. We should stop all the cooper pairs simultaneously to cease the current flow. As the superconductor is warmed, its Cooper pairs separate into individual electrons, and the material becomes normal or non-superconducting. Superconductors abrupt

Optical Fiber

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Optical fiber An optical fiber is a flexible glass or plastic fiber that can transmit light from one end to the other. Such fibers are used widely in fiber-optic communications. They permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables. Fibers are used instead of metal wires because signals travel along them with less loss and are immune to electromagnetic interference. [7] They can carry light into or images out of confined spaces, as in the case of a fiberscope. [8] Specially designed fibers have a variety of other applications, such as fiber optic sensors and fiber lasers. [9] Drawing is a process for making glass optical fibers. For plastic fibers, we can choose either drawing or extrusion . [10][11] Optical fibers typically include a core surrounded by a transparent cladding material with a lower index of refraction. The core keeps the light in the core by total internal reflection, which causes the fiber to act as a wave