Hannah's+Telescope+Lab

=Telescope Spyglass Lab= March 25, 2010
 * Participants**: Hannah Mollmark
 * Purpose**: The purpose of this lab is to understand the refraction of light through lenses in order to create an image of an object. Using the correct placement of the lenses (based on the measurements of the different lenses' focal points) we were able to build a telescope that magnified the image of an object that was an infinite distance away. By doing this, we learned how the lenses create this image: the first lens flips the image upside down, the second lens flips the image back the right way around, and the third magnifies the image of the right-side-up image.

A.Full telescope (built by Marissa and Hannah); B.Along the telescope looking at the the image we were trying to magnify; C.Magnified image through the telescope. D.Full lens/telescope diagram. (The diagram is scaled down to 25% the size of the actual telescope.) E.Close-up of the three lenses; F.Close-up of the last two lenses (object is to the right): 1:Point where the image should appear flipped. 2.Point where the rays actually met in the diagram; this difference is due to the fact that the object was drawn a distance of only three focal lengths away when in reality, the object was much further away. This results in a slight difference in where the image appears. 3.Point where the rays intersect and second image appears flipped right side up. (The closer the image is to the focus, the greater the magnfication will be.) 4.Point where the rays intersect and the third image appears magnified.
 * Brief Description of Experiment**: To begin the experiment, we did a series of drawings and measurements in order to understand and get used to how light rays refract when they go through a lens. We started by placing one lens on the yard stick and using the light from the back window to determine the focal length. We did this by placing an index card on the yard stick and finding the point where the image of the window through the lens is most in focus. The distance betwen the lens and image is the focal length. We then added a second lens which was the distance of the two focal lengths added together. We were then able to use it as a telescope but the image was upside down. We then determined where to add a third lens, but the image was still upside down. From here we learned that the light that came from the outside affected the image that we saw through the lenses. So we created a tube of rolled up poster board to block outside light; this prevented excess light to change what we were supposed to see. The tube allowed for us to see an image that was both magnified and right side up.
 * Data**: Create a table (when appropriate) including all data collected or calculated during the lab. Be sure to include a heading for each column that includes the units of each measurement.

focal length = (object distance x image distance) / (object distance + image distance) || magnification = focal length of the objective / focal length of the eyepiece || Our favorite combination of lenses for the telescope was the objective with a focus of 41.7cm and the eyepiece with a focus of 9.7cm. These two lenses were placed a distance of 51.4cm apart (the sum of the two focal lengths). The magnification, which was calculated by dividing the focal length of the objective by the focal length of the eyepiece, was 4.299. Graph: Magnification vs focal lengths. As the focal length decrerases, the magnification increases.
 * Sample Calculations:**
 * //Focal length calculation// || The focal length in centimeters was calculated by taking the object distance in centimeters and multiplying it by the image distance in centimeters and then dividing that product by the sum of the object distance (in cm) and the image distance (in cm).
 * //Magnification calculation// || The magnification was calculated by dividing the focal length of the objective, in centimeters, by the focal length of the eyepiece, in centimeters.
 * Results**: A basic telescope was built and the understanding of its workings were understood. This allowed for the knowledge of focal points and lenses to be acquired and applied to a real-life invention. Focal lengths were calculated and we had to use problem-solving skills in order to better our telescope and make it work effectively.
 * Choose your favorite combination of lenses for the telescope and describe its properties.**


 * Conclusion**: I believe that the experiment produces a valid and reproducible result because we were able to actually see how it worked and the differences that resulted from making changes to the telescope itself. The specific lenses we used had certain focal lengths which secures the same necessary set-up when creating a working telescope. This results in a reproducible structure. A simple improvement to the experiment would be to secure the placements of the lenses so that they don't shift when inserting the tube or checking measurements. In addition, we had to have two separate tubes, one between the first and second lenses and another between the second and third. If we could have used one tube that reached from the first to the third lens, it may have resulted in a better and more accurate image.

//Don't forget to link to your lab report from the lab reports page and to include a link to your lab report in your reflection.//