MIP 300 Lecture Notes - Bright-Field Microscopy, Tuberculosis, Flagellum
28 Jun 2014
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Document Summary
When rays of light pass from one medium to another (i. e. air to h2o) the rays bend refraction. Refractive index measure of how greatly a substance slows the velocity of light. Amount and direction of bending are determined by the refractive indices of the interfacing substances. Magnification = (objective) (eyepiece) (40x objective) (10x eyepiece) = 400x magnification. Ability of lens to distinguish between objects is resolution or resolving power. Only used to see shape, size and arrangement. Viruses = ~0. 01 0. 1 m, too small to see with light microscope. Background appears light, bacteria are color of stain. Good for looking at things that are still alive. Phase contrast converts slight differences in refractive indices into easily detected variations in light intensity. Fluorescent microscopy uses a uv light to excite fluorescent molecules such as green. Before staining microbes must be fixed to slide. Simple stain: 1 stain used to increased microbes" visibility.
