What Do You Know about Lenses?

  1. Assessing prior Knowledge:
    Choose a picture and as many descriptions as you can for each question.
    Do not talk to your neighbor until you are told to do so.

      c. converging   d. diverging   e. concave   f. convex

    1. ________ Which lens is used for people who can see very well up close, but not distances?
    2. ________ Which lens is used to magnify small print?
    3. ________ Which lens is used for a peep hole in a front door?
    4. ________ Which lens makes distant objects upside down?
    5. ________ Which lens would you use to start a fire with sunlight?

  2. Exploration (Conceptual):
    With partners, discuss your answers. Put question marks by any that have disagreement.

    1. With a distant object (sun, trees) try to focus its image on paper. If you can get an image on paper, it is called a real image.
      2. Describe the lens and the image that you got.

    2. With which lens do you see the image only by looking through the lens (not on paper)?
      That is a virtual image.
      Describe lens(es) and images that you got.

    3. For the convex lens (one that is fat in the middle) decide if it converges light or diverges light. Tell what you did.

    4. For the same lens find and describe the images when the object (light) is far from the lens, closer, still closer.
      Did you always get real (on paper) images?
      Draw diagrams or take notes.

    5. For the concave (skinny in middle) lens do #4.

    6. For the concave (skinny in middle) lens do #5.

    7. Summarize on white board what you discovered for both lenses.
      1. Draw diagrams of the lens, object, and image.
      2. Use stick figures for the object and image (rather than the light).
      3. Label them O (object) and I (image).

      4. Now, go back and see if you can answer any more of the questions in I.
      5. Relate those answers to your summary on the white board.

    Lenses Lab.
    Index for lenses.

    Andria Erzberger
    2/1/01