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GCSE Bitesize was launched in January 1998, covering seven subjects. For each subject, a one- or two-hour long TV programme would be broadcast overnight in the BBC Learning Zone block, and supporting material was available in books and on the BBC website. At the time, only around 9% of UK households had access to the internet at home.
An LCD screen used as a notification panel for travellers. Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes called alignment layers, [citation needed] often made of indium tin oxide (ITO), and two polarizing filters (parallel and perpendicular polarizers), the axes of transmission of which are (in most of the cases) perpendicular to ...
Convergent beam electron diffraction (CBED) is an electron diffraction technique where a convergent or divergent beam (conical electron beam) of electrons is used to study materials. CBED scheme, adapted from W. Kossel and G. Möllenstedt, Elektroneninterferenzen im konvergenten Bündel, Annalen der Physik 36, 113 (1939).
Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials. [2] An instrument dedicated to performing such powder measurements is called a powder diffractometer .
Because diffraction is the result of addition of all waves (of given wavelength) along all unobstructed paths, the usual procedure is to consider the contribution of an infinitesimally small neighborhood around a certain path (this contribution is usually called a wavelet) and then integrate over all paths (= add all wavelets) from the source to the detector (or given point on a screen).
X-ray diffraction is a generic term for phenomena associated with changes in the direction of X-ray beams due to interactions with the electrons around atoms. It occurs due to elastic scattering, when there is no change in the energy of the waves. The resulting map of the directions of the X-rays far from the sample is called a diffraction pattern.
Kinematic diffraction is an approximation for diffraction of waves. It assumes that the waves are only scattered once, neglecting multiple scattering . For linear wave equations , it i volves summing the contribution of the partial waves emanating from different scatterers, where only the incident field drives the scattering.
A geometrical arrangement used in deriving the Kirchhoff's diffraction formula. The area designated by A 1 is the aperture (opening), the areas marked by A 2 are opaque areas, and A 3 is the hemisphere as a part of the closed integral surface (consisted of the areas A 1, A 2, and A 3) for the Kirchhoff's integral theorem.