Magnification, determination from

Conversely the separation can be determined from the primary focal length, the magnification of the secondary and the back focal length. 

Trophic magnification TMF The increase in concentration of a chemical in relation to the position of the organism in the food web. The position in the food web is determined from the change in ratio of I5N to 14N in the food web... 

Arteries are punctured with a hypodermic needle (25 gauge 16 x 5/10 mm). The bleeding time of the mesenteric blood vessels is observed through a microscope at a magnification of 40 x. The time in seconds is determined from the puncturing until the bleeding is arrested by a hemostatic plug. 

R /f is the numerical aperture (N.A.) and is marked on all objective lenses, together with the magnification. For example, a x25 objective with N.A. = 0.5 is expected to resolve detail of the order of 2X 1 m, ideally. Equation (2.1) has been derived by considering diffraction by a coherently illuminated periodic object. Rayleigh s well-known criterion of resolution, derived for a nonperiodic object incoherently illuminated, gives nearly the same limit of resolution as that determined from the Abbe approach and need not be considered here (see, e.g., Giancoli 1984). 

Figure 2. Scanning electron micrographs (at three magnifications) of a fire flood emulsion illustrating a case in which, although the water-oil ratio is 2.5 1, water is the dispersed phase. The composition of this emulsion is 63% water, 11% solids, and 26% oil. The compositions of the dispersed and continuous phases were determined from the X-ray signal excited in the electron microscope. The size of the dispersed water phase ranges from less than 0.1 pm up to about 10 pm. The large features labeled O are regions of oil phase that can be described as oil emulsified in a continuous phase of a water-in-oil emulsion. These complex systems are difficult to characterize with anything but microscopic methods.

Crystals For crystals, or pressed materials with a very low porosity, the effective surface area can be readily determined from the known sample geometry. It is convenient to use for this purpose an optical microscope with a scale and magnification of 20-30. The absolute rate of decomposition is evaluated by dividing the change in sample mass per unit time. Am/At, measured under isothermal conditions, by the area of the external surface of the crystal at the instant of the measurement Sn... 

Optical interferometry can be used to measure surface features without contact. Light reflected from the surface of interest interferes with light from an optically flat reference surface. Deviations in the fnnge pattern produced by the interference are related to differences in surface height. The interferometer can be moved to quantify the deviations. Lateral resolution is determined by the resolution of the magnification optics. If an imaging array is used, three-dimensional (3D) information can be provided. 

An ocular micrometer is a disk on which is etched a scale in units from 0 to 50 or 100. To determine the micrometer value of each unit in a particular eyepiece and at a specific magnification, the unit must be calibrated with a stage micrometer. A stage micrometer has a scale 2 mm long ruled in fine intervals of 0.01 mm (10 finl). 

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