Discussion of the section
on diffraction gratings and the spectrum Here are some things to do to finish this section.
Did you think of a question that could be studied, or make an observation
that was interesting or unexpected? You should send it to the Question
board!
Discuss these questions with the people in your group:
What does the spectrum of a very red light look like? How does it
differ from the spectrum of a blue light or a green light?
Suppose you had black-and-white photographs of these spectra --
would you be able to identify which was which?
(We will assume that
the film records any bright light as if it were white).
How many different spectra can you find around the school, your house, or
outside at night? It isn't very easy to record them, but try at least to classify them in some way. When is the spectroscope useful, and when is it easier to use just a diffraction grating?
A compact disk makes colored light from white light. Study a CD as
follow: on a sunny day, find a way to prop up the CD so that it makes
a mirror reflection that you can see 20 or 30 feet away.
Starting from the place where you
see the sun's reflection as a brilliant white glare, walk to the right or
left. After you have travelled a small distance, you will note that now
the CD is reflecting a color. Observe what colors you see in what order.
Compare
this to what you see looking at the light bulb through a diffraction
grating.
How are the CD and the diffraction grating alike, and how are they different?
These discussion questions are a bit open-ended, and some people find them
very confusing. We have provided
some examples of good and bad discussionss on a
separate page.
Please send
us your discussion of two of these questions -- the one you are most sure
about and the one you are least sure about (and tell us which is which!).
Don't forget to tell us who is in the group.
If there is something that you don't understand about light and shadows,
Ask
us!
This is the end of this section.
The
next section is about color You should go there
next if this is your first time through. There are several other pages
to look at sometime:
The activities are also written up (in a slightly different form) in the
manual (in the Color section).
Starting from the place where you
see the sun's reflection as a brilliant white glare, walk to the right or
left. After you have travelled a small distance, you will note that now
the CD is reflecting a color. Observe what colors you see in what order.
Compare
this to what you see looking at the light bulb through a diffraction
grating.
How are the CD and the diffraction grating alike, and how are they different?