Definition noun (1) The measure of transmittance of an optical medium for a given wavelength. The higher the OD the lower the transmittance, the higher protection factor by a filter (e.g. goggles, viewing windows, etc.). (2) The measure of the amount of light absorbed by a suspension of bacterial cells or a solution of an organic molecule with the use of a colourimeter or spectrophotometer. Supplement In microbiology, the values can be used to measure turbidity, which in turn is used to estimate the number of bacteria (or concentration of molecules like proteins) in a solution. Abbreviation: OD Synonym: absorbance. See also: absorption.

Optical density definitionin spectroscopy

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Optical density definitionradiography

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where n is the refractive index of the material. It is simple to show that when light meets a surface at the polarising angle the reflected and refracted beams are at right angles to each other. Notice also that the reflected and refracted light has vibrations along the surface at the point of incidence. For glass with n = 1.54 the polarising angle = 57o. Since n varies with the colour of the light, white light can never be perfectly polarised by reflection. The front of a glass door in a cupboard can show excellent polarisation by reflection.The following diagram shows how we can use two mirrors as a polariser and analyser arrangement.

Optical densityformula

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Optical density definitionchemistry

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Polaroid sunglasses will cut out the reflected glare from roads because the reflected beam is partly or totally polarised. This polarisation occurs when light is reflected from any non-conductor of electricity. Whether the polarisation is total depends on the surface and the angle of incidence. [Note: Vibrations in the plane of the paper are shown as lines and ones at right angles to the paper are shown as dots.] For a particular angle p, the beam is completely plane-polarised, the reflected light being polarised as shown in Figure 5; p is known as the polarising angle for that material.Brewster found that:

In this tutorial, the works of Carl Gustav Jung and Sigmund Freud are described. Both of them actively pursued the way h..

Definition noun (1) The measure of transmittance of an optical medium for a given wavelength. The higher the OD the lower the transmittance, the higher protection factor by a filter (e.g. goggles, viewing windows, etc.). (2) The measure of the amount of light absorbed by a suspension of bacterial cells or a solution of an..Read More