have been doing Science Day in Sandy Hook for many years.
This year we decided to replicate our part of it for the 4th through
6th graders in Lakeside and Isonville.
In Sandy Hook
Nancy had classes with the younger kids and they learned about how the
eye works and some of the ways it can be fooled.
Here is a diagram of the eye with the names of its parts.
Optical illusions and hidden pictures show how the eye can be
The kids here are looking for a baby in this picture.
Some found it immediately others had to have it pointed out to
Here is a copy for you to try your powers of observation.
Perception of light and dark areas
depends strongly on what is around them..
Two gray areas (A and B) are the same. If you don't believe me make 2 holes
in a sheet of paper so that you can only see those 2 areas. When you cover the rest you will see
that they are the same.
Sometimes your eyes will tire of
seeing some colors and will surprise you when you look at a blank white
area. Here this strangely colored flag can
be used to demonstrate the effect.
To see the effect stare at the lower
right corner of the yellow part of the flag for 30 seconds or more. Try to keep your eyes focused on
exactly the same spot. Now look at a blank sheet of paper or
wall to see what colors you see.
I think this fellow was surprised.
The older kids investigated spectra. I aimed three laser pointers at the
same spot on the left of this picture then used a diffraction grating
to separate their colors. The first cluster of three spots show
that blue (which has the shortest wavelength) isn't deflected as far as
the green and red with the longest wavelength is deflected the most. The same pattern is repeated with a
wider spread in the second order spots on the right of the picture..
Each photon of the shorter
wavelengths (blue and ultraviolet) carry more energy than those with
longer wavelengths (other visible colors and infrared) This video shows the effect of three
different colors of laser light on beads that react when sufficiently
energetic photons hit them. Even though the green laser is much
brighter photons from it don't deposit enough energy in the beads to
have any effect on them.
We can see the colors that are
produced by elements when they are excited by fire. Here we have the chlorides of strontium, potassium,
copper, calcium, and sodium,
Here you can see the spectra of the copper (cupric chloride) flame. The central flame is a bright green so it is overexposed and looks nearly white except around the edges. The diffraction grating separates the colors in the eight images around it. They are most easily seen at sharp edges of the flame.
Spectra can also be produced when high
voltage electric current is passed through gaseous elements in
Here are what the unexcited tubes look
And here is the spectra
produced by two of the tubes The nearly white line on the left of
this picture is what you see before the lines have been separated and
those to the right are the spectra of helium.
Xenon discharge tube
The kids used defraction gratings to
make spectroscopes. Here are the spectra of several
different lights. By comparing what they see looking
through their spectroscope they can figure out what kind of light they
are looking at.
Spectra can be used to identify
elements in distant light sources.
Individual elements can be identified
in mixtures. Here the dark lines show what you see
if an incandescent light such as the sun or the filament of an old
style light bulb passes through a gas.
Here is a solar spectrum. In order to show all the lines it has
been broken into parts. Each horizontal band should be joined
to the right end of the one above it to make a single very long
This is what it looks like in the room when the neon tube is
Some of the kids are using the spectroscopes that they made to
check its spectrum.
Here are pictures of the classes
checking the spectra
of various other light sources in their classrooms.
Science can be amazing and I love it
when the kids react like this to one of our demonstrations.