Telescope Making with Troop 1223 Brownies
January 25, 2007
First we measured the focal lengths of the lenses, and tried them out individually as magnifying glasses.
Then we assembled the telescopes. It wasn't too hard. We wondered about the cardboard donuts though. Mr. Brown says that's a homework assignment.
We couldn't wait to try them out. We went into the school hallway to get a nice long view.
And finally we decorated our scopes with markers.
Other things we learned:
Never look at the Sun.
We can look at the Moon with these telescopes! In fact, we can look at practically anything, except one.
The small lens is called the eyepiece. The big lens is called the objective.
The focal length of the objective is about 17 inches, the eyepiece is about 1 inch. (our measurements are a little coarse.)
The focal length of the objective divided by the focal length of the eyepiece equals the magnification. 17/1 = 17 times magnification. That means things look 17 times bigger!
The image is upside-down! The same thing happens in our eyes.
What is the cardboard donut all about?
Try this: Take out the donut and reassemble the telescope. Now hold the donut just in front of the objective lens and look at a far away street light. Now remove the donut. What happens? Does the image change in any way? Send me an email telling me what you find.
mailto:mcculloch-brown@comcast.net
Thank you to Learning Technologies, Inc. for generously providing the telescopes!
http://www.starlab.com/index.html