LENS IMAGES: A Virtual Activity
Go to the web site http://www.schulphysik.de/suren/Applets.html. From the “Applet Menu” pull-down menu, choose “Optics” and “Spherical Mirrors and Lenses.” After you click on the box, you will see a window open that allows you to choose either a convex (converging) lens or a concave (diverging) lens.
Part I - Images in a Converging Lens
With the simulation set on “convex lens,” move the object to various distances to the left of the lens. Make sketches or use a screen capture program (http://www.etrusoft.com/) to show rays forming the image and the location of the image when the object distance is:
1) more than twice the focal length away,
2) exactly twice the focal length away,
3) between one and two focal lengths away,
4) exactly one focal length away, and
5) less than one focal length away.
On each sketch or captured image, state whether the image is:
a) real, virtual, or no image formed,
b) upright or inverted, and
c) reduced, enlarged, or the same size.
Part II - Images in a Diverging Lens
Now set the simulation to “concave lens” and repeat this procedure.
Part III - Object and Image Location Relationship in a Converging Lens
By moving the object to varying distances to the left of the converging (convex) lens, use this simulation to make a data table of object distance and image distance for a set focal length. You can move the focal point by clicking on it and dragging it to a new position.
Graph I / Graph IIFocal length / Object distance / Image distance / Focal length / Object distance / Image distance
100 / 25 / 150 / 25
100 / 50 / 150 / 50
100 / 75 / 150 / 75
100 / 100 / 150 / 100
100 / 125 / 150 / 125
100 / 150 / 150 / 150
100 / 175 / 150 / 175
100 / 200 / 150 / 200
100 / 250 / 150 / 225
100 / 300 / 150 / 250
100 / 350 / 150 / 275
100 / 400 / 150 / 300
100 / 450 / 150 / 325
100 / 500 / 150 / 350
Make graphs of “Image Distance vs Object Distance” for each of these constant focal length values. Place both of these graphs on the same coordinate axes and compare them.