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Standing wave

Standing wave
Two opposing waves combine to form a standing wave. For waves of equal amplitude traveling in opposing directions, there is on average no net propagation of energy. Moving medium[edit] As an example of the first type, under certain meteorological conditions standing waves form in the atmosphere in the lee of mountain ranges. Such waves are often exploited by glider pilots. Standing waves and hydraulic jumps also form on fast flowing river rapids and tidal currents such as the Saltstraumen maelstrom. Opposing waves[edit] In practice, losses in the transmission line and other components mean that a perfect reflection and a pure standing wave are never achieved. Another example is standing waves in the open ocean formed by waves with the same wave period moving in opposite directions. Mathematical description[edit] In one dimension, two waves with the same frequency, wavelength and amplitude traveling in opposite directions will interfere and produce a standing wave or stationary wave. and

Optics on the Web Links to optics-related applets, tutorials and web sites of interest. NOTE: Some applets no longer work with the most recent Java. If possible, try running on an earlier version. In some cases, I've found alternate applets that are similar and that will run on most browsers (I use Chrome, Safari and Firefox). If you find a link that doesn't work, please email me. Applications of Optics in Communications (Fiber Optics), Manufacturing, Medicine (including the eye) and More Societies, Organizations and Online Magazines This site contains a huge collection of tutorials and applets covering most of an introductory optics course. This is an optics tutorial for chemistry students. optics tutorial with an ophthalmic slant, including how corrective lenses work

The Physics Classroom Interference (wave propagation) Swimming Pool Interference[1] Interference of waves from two point sources. Magnified-image of coloured interference-pattern in soap-film. The black "holes" are areas where the film is very thin and there is a nearly total destructive interference. Consider, for example, what happens when two identical stones are dropped into a still pool of water at different locations. Geometrical arrangement for two plane wave interference Interference fringes in overlapping plane waves A simple form of interference pattern is obtained if two plane waves of the same frequency intersect at an angle. It can be seen that the two waves are in phase when and are half a cycle out of phase when Constructive interference occurs when the waves are in phase, and destructive interference when they are half a cycle out of phase. and df is known as the fringe spacing. The fringes are observed wherever the two waves overlap and the fringe spacing is uniform throughout. A point source produces a spherical wave. for to where

String theory String theory was first studied in the late 1960s[3] as a theory of the strong nuclear force before being abandoned in favor of the theory of quantum chromodynamics. Subsequently, it was realized that the very properties that made string theory unsuitable as a theory of nuclear physics made it a promising candidate for a quantum theory of gravity. Five consistent versions of string theory were developed until it was realized in the mid-1990s that they were different limits of a conjectured single 11-dimensional theory now known as M-theory.[4] Many theoretical physicists, including Stephen Hawking, Edward Witten and Juan Maldacena, believe that string theory is a step towards the correct fundamental description of nature: it accommodates a consistent combination of quantum field theory and general relativity, agrees with insights in quantum gravity (such as the holographic principle and black hole thermodynamics) and has passed many non-trivial checks of its internal consistency.

Numerical aperture The numerical aperture with respect to a point P depends on the half-angle θ of the maximum cone of light that can enter or exit the lens. General optics[edit] In most areas of optics, and especially in microscopy, the numerical aperture of an optical system such as an objective lens is defined by is constant across an interface. In air, the angular aperture of the lens is approximately twice this value (within the paraxial approximation). In microscopy, NA is important because it indicates the resolving power of a lens. Numerical aperture is used to define the "pit size" in optical disc formats.[2] Numerical aperture versus f-number[edit] Numerical aperture is not typically used in photography. , which is defined as the ratio of the focal length to the diameter of the entrance pupil: This ratio is related to the image-space numerical aperture when the lens is focused at infinity.[3] Based on the diagram at the right, the image-space numerical aperture of the lens is: thus , and not where

Quantum information In physics and computer science, quantum information is information that is held in the state of a quantum system. Quantum information is the basic entity that is studied in the growing field of quantum information theory, and manipulated using the engineering techniques of quantum information processing. Much like classical information can be processed with digital computers, transmitted from place to place, manipulated with algorithms, and analyzed with the mathematics of computer science, so also analogous concepts apply to quantum information. Quantum information[edit] Quantum information differs strongly from classical information, epitomized by the bit, in many striking and unfamiliar ways. Among these are the following: A unit of quantum information is the qubit. The study of all of the above topics and differences comprises quantum information theory. Quantum information theory[edit] How is information stored in a state of a quantum system? Journals[edit] See also[edit]

Optical fiber cable A TOSLINK optical fiber cable with a clear jacket. These cables are used mainly for digital audio connections between devices. An optical fiber cable is a cable containing one or more optical fibers. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed. Design[edit] A multi-fiber cable Left: LC/PC connectors Right: SC/PC connectors All four connectors have white caps covering the ferrules. For indoor applications, the jacketed fiber is generally enclosed, with a bundle of flexible fibrous polymer strength members like aramid (e.g. Fibre-optic cable in a Telstra pit An optical fiber breakout cable For use in more strenuous environments, a much more robust cable construction is required. A critical concern in outdoor cabling is to protect the fiber from contamination by water. Capacity and market[edit] Reliability and quality[edit] Cable types[edit] Jacket material[edit]

John C. Lilly John Cunningham Lilly (January 6, 1915 – September 30, 2001) was a American physician, neuroscientist, psychoanalyst, psychonaut, philosopher, writer and inventor. He was a researcher of the nature of consciousness using mainly isolation tanks,[1] dolphin communication, and psychedelic drugs, sometimes in combination. Early life and education[edit] John Lilly was born to a wealthy family on January 6, 1915, in Saint Paul, Minnesota. His father was Richard Coyle Lilly, president of the First National Bank of St. Lilly showed an interest in science at an early age. While at St. Despite his father's wishes for him to go to an eastern Ivy-league college to become a banker, Lilly accepted a scholarship at the California Institute of Technology to study science. In 1934, Lilly read Aldous Huxley's Brave New World. Lilly became engaged to his first wife, Mary Crouch, at the beginning of his junior year at Caltech. At the University of Pennsylvania, Lilly met a professor named H. Research[edit]

Diffraction Diffraction pattern of red laser beam made on a plate after passing a small circular hole in another plate Diffraction refers to various phenomena which occur when a wave encounters an obstacle or a slit. In classical physics, the diffraction phenomenon is described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings. These characteristic behaviors are exhibited when a wave encounters an obstacle or a slit that is comparable in size to its wavelength. Similar effects occur when a light wave travels through a medium with a varying refractive index, or when a sound wave travels through a medium with varying acoustic impedance. Diffraction occurs with all waves, including sound waves, water waves, and electromagnetic waves such as visible light, X-rays and radio waves. Richard Feynman[3] wrote: The formalism of diffraction can also describe the way in which waves of finite extent propagate in free space. Examples[edit] History[edit] where