Exploring colored filters Here are some things to think about and do as we start the unit on
colored filters. These questions can be answered by simple experiments
that will only take a few minutes. Do most of them, and for the rest discuss
with your group how you might do the experiment. You also may be
able to discuss what you predict will be observed (if it is a situation
with which you are already familiar).
In a darkened room, shine a white light on an object (a desk light works
well for this), and place a colored filter between the light and object
- blocking all of the white light and only letting one color reach the
object at a time. By doing this you are effectively making colored
light - red, blue, or green. (You could also accomplish the same thing
by illuminating an object with a single colored light bulb.) What
does a red object look like, when illuminated wtih red light, and how different
does it look when viewed in only green light? And what about green
objects - how do they look in red or green light?
Can you find objects which don't look red (or black) when illuminated with
red light?
Is there any difference between viewing an object illuminated with red
light, and what you see if you hold the filter up to your eye and look
at the object through the red filter?
What color light do you get when you combine two colored filters, or even
all three?
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? On
to the first activity!