# A Simple Telescope: Worksheet

 Fall 2005 ASTR 110L, Sec. 2 Name: ________________

1. Using only the objective lens and some tissue paper fastened to the other end of the tube, form an image of the three colored lights. Then sketch the following:

 Real-life object orientation. Projected image orientation.

2. Using a distant light source, measure the focal length, F, of the large objective lens. Include units! Then, estimate the error in your measurement, and convert it to a percentage.

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3. Using a distant light source, measure the focal length, f, of the small eyepiece lens. Include units! Then, estimate the error in your measurement, and convert it to a percentage.

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4. Calculate the magnification, M, of the simple telescope. Show your formula and your work. Round off your final answer to an appropriate number of significant digits. This is the theoretical magnification that we expect the simple telescope to deliver.

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5. Measure the magnification of the simple telescope by observing the 1-meter target set up in the hallway. This is the experimental magnification the telescope actually delivers.

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6. Do your two magnifications (theoretical end experimental) agree with each other, given the possible errors in your measurements? If not, can you think of other sources of uncertainty?

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 Joshua E. Barnes (barnes@ifa.hawaii.edu) Last modified: September 14, 2005 http://www.ifa.hawaii.edu/~barnes/ASTR110L_F05/simplescope_WS.html