Exploring light energy
Light plays several different roles in our lives. It delivers information (that's what vision is all about), but it also delivers energy, which causes chemical change and warming. This latter aspect of light is the subject of this section.

Here are some things to think about and do as we start the unit on light energy.

  1. Give examples of light delivering information, and examples of light doing other things.
  2. The discussion of light in the preceding sections has tended to be stated in terms of the information content of light: we were interested in images. Give examples of the use of shadows, colored filters, mirrors, and lenses, where it is the energy aspects of light that are of interest.
  3. Here are some pictures showing a lens at various distances from a screen that is being illuminated by a distant light bulb. The effect of the lens is to make a dark ring and a bright disk. Discuss these pictures from the point of view of the energy carried by the light. (You should do this for yourself -- the pictures don't quite capture the way it really looks).
    The lens is too far from the screen. The light has passed its point of convergence and is diverging again
    Still too far
    Just right
    Too close

As part of your discussion, write something in your notebook about your answers to some of these questions -- what you decided, which questions you were sure of, which ones don't seem to make sense.
All done?  Luminescent paper