Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Do you see what I see?



Here are three somewhat related questions:

1. Draw a vertical chalk line on the blackboard and then step back a few
meters. With your index finger a few inches in front of your eye,
slowly push it across the line. Just before your finger eclipses the
line, the line will seem to bow ahead of your finger. Is this due to
diffraction, the width of the pupil, or ????

2. Why do so called "flourescent" colors (hot pink, day glo orange) seem
so bright. Nothing can reflect more light than white, and any dye only
produces a color other than white by absorbing wavelengths. So why do
these colors seem to leap out at me?

3. In all my years of teaching physics, I have never seen an explanation
of how surfaces produce their characteristic color. I know well enough
that matte red paper is red because it absorbs all colors but red (and
most likely some orange), but how are all the all other colors
absorbed? How can the molecules absorb a tremendous range of
frequencies at once? And how can one group of frequencies reflect off
this surface? Is it reflected or reemitted? What's the actual
mechanism involved?

Thanks for the expertise of those who repond.

Ken Kiehlbauch
Faith Academy
Manila, Philippines