CELL201- Final Exam Guide - Comprehensive Notes for the exam ( 42 pages long!)
29 Mar 2018
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Document Summary
Three elements needed to form an image: source of illumination, system of lenses, a specimen. Wavelength of the source limits the size of the object that can be seen through the microscope. Smaller the wavelength, smaller the objects that can be seen. Angular aperture is the measure of how much of illumination that leaves the specimen passes the lens. Angular aperture determines sharpness and is an important factor that influences resolution. Three factors that influence resolution: the wavelength of light, angular aperture, refractive index of the medium. Refractive index is the measure of the change in velocity of the light as it passes from one medium to another. r= resolution (how close two points can be and still be distinguished) 0. 61 defines the degree to which images can overlap but still be recognised as separate points. nsin = na= numerical aperture of the objective lens: resolution for light microscope= 200nm, resolution of electron microscope= 2nm.
