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2.9: Microscopes and Telescopes

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  • Figure shows from left to right: an object with height h, a bi-convex lens labeled objective lens at a distance d subscript o from the object, an inverted image with height h subscript i labeled first image at a distance d subscript i from the objective lens, a bi-convex lens labeled eyepiece at a distance d subscript o prime from the first image and finally the eye of the observer. Rays originate from the top of the object and pass through the objective lens to converge at the top of the inverted image. They travel further and enter the eyepiece, from where they deviate to reach the eye. The back extensions of the deviated rays converge at the tip of a much larger inverted image to the far left of the figure. The height of this image is h subscript i prime and its distance from the eyepiece is d subscript i prime.
    Figure \(\PageIndex{8}\):The Hubble space telescope as seen from the Space Shuttle Discovery. (credit: modification of work by NASA)

    The angular magnification \(M\) of a reflecting telescope is also given by Equation \ref{eq2.36}. For a spherical mirror, the focal length is half the radius of curvature, so making a large objective mirror not only helps the telescope collect more light, but also increases the magnification of the image.


    • Samuel J. Ling (Truman State University), Jeff Sanny (Loyola Marymount University), and Bill Moebs with many contributing authors. This work is licensed by OpenStax University Physics under a Creative Commons Attribution License (by 4.0).