Optics Discovery Kit
Experiment #3 : GALILEAN TELESCOPE


EQUIPMENT: Lenses A and C and Two Clothes pins

CAUTION! DO NOT LOOK AT THE SUN!

MAGNIFY IMAGES Hold lens C very close to one eye so that it almost touches your eyebrow. Put lens A directly behind and very close to lens C so that you can look through C at A. For the next step, close your other eye. Aim the lenses toward some distant object and very slowly move lens A away from lens C (keep lens C right at your eye). At some point you should see a sharp (focused) image of the distant object appear. If the image is too shaky, you can set the lenses on a table using clothespins to make them stand up.
1) Describe the image compared to the object.
2) Draw the image on paper so that your drawing seems the same size as the image you see. Also draw on the paper the object the size it appears when you look at it without using the lenses.
3) Measure the length of your two drawings to find out how much the TELESCOPE you made magnifies the distant object.

HOW IS THIS USEFUL? BINOCULARS are two telescopes mounted side by side. They enlarge the image of distant objects. TV cameras with long lenses act as telescopes that allow us to view close up pictures of objects distant from the cameraman.

List of Other Experiments


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Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1504
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Optics Discovery Kit © the Optical Society of America

URL: http://acept.la.asu.edu/PiN/opticskit/expt/experiment3.shtml