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Dear Jorge,
There are dozens of experiments!
1. Angle of incidence = angle of reflection using a pinhole in a
piece of card placed over a flashlight to see the beam (using a
little chalk dust on an eraser to accentuate), bounced off a
mirror Also, discuss specular vs. diffuse reflection using a
smooth pond vs. a wavy pond
2. Polarization on reflection using a lens from a polarizing sunglass
and looking at the reflection from water "sitting up" versus "lying
on your side" (Polarized sun glasses only work when you are
vertical... always surprising to students). Also, how polarized
light "removes" surface reflection
3. Refraction using a glass stirring rod in a glass of water
(interesting follow-up question: if you are standing in a river and
trying to catch a fish which is about to swim through your legs,
where would you reach to catch the fish?)
4. "Red resists refraction" (basis for rainbows) using a simple prism
5. Double refraction of minerals using a simple calcite crystal
placed on writing on a paper
6. Diffraction, Constructive and Destructive interference looking at
a light source (lamp) through very narrow slits between your fingers)
7. Stress/strain patterns in nearly all molded plastic pieces (look
at them between crossed polars, such as 2 lenses from polarized sunglasses)
9. Refractive index: "Disappearing" glass - put a glass or plastic
stirring rod (refractive index ~1.5) into a glass of silicon oil
(refractive index 1.5) (refractive index of air is 1.0). Great for
discussing why we "see" things (differences in refractive index)
10. Looking at a fried egg with different colored filters (egg yolk
will "disappear" with red and, often, green filters; will appear
black with blue filter.. great for discussing what filters are and
why we see the colors we do)
11. Whole series of experiments with simple hand lens... (a) Find
the focal point (b) Front and back focal planes (c) 4 cases of
lenses using your finger as the object (placed inside the focal
point, at the focal point, beyond the focal point and, via
discussion, a very long distance from the focal point) [this one is
great fun because their fingers appear upright and magnified INSIDE
the focal point; disappear AT the focal point; and flip upside down
OUTSIDE of the focal point... and you can say "at no time did your
finger leave your hand" .. which always makes students laugh] (d)
Real versus virtual images.
12. How a drop of water can act as a lens (lessons: refractive
index; image formation, Leuwenhook's early microscopes - which used a
glass bead as a lens)
13. Use a simple black light to discuss fluorescence. (An
interesting experiment is to use grass or a leaf which appears green
in sunlight but fluoresces red. Grass, leaves, etc. are always
fluorescing red, but we never see it... ask them why not?)
Any simple microscope is also an amazing lesson in optics. Focus on
a simple stained specimen then remove the eyepiece. Discuss
"conjugate optical planes" and the two sets of planes that exist in
the microscope; the one that carries the illumination information
(and the Fourier transform of the image... another great experiment,
which can be demonstrated using a simple grating as a specimen) and
the other that carries the image information. Also can demonstrate
that "Blue resists Diffraction" ... basis for why shorter wavelengths
produce higher resolution images).
Once they understand conjugate focal planes, "play" with light by
opening the aperture iris (condenser) sliding a piece of card stock
flat across the bottom of the condenser to create oblique
illumination; Use a simple darkfield patch stop (you can even make
them using India ink on a piece of plastic like an overhead foil) to
create darkfield; Create Rheinberg illlumination used a colored
patch stop. You can demonstrate the physics by removing the sample,
dropping the stage, rotating the objective out of the way and using
either a piece of card stock standing vertically on the stage or a
piece of plastic (like screwdriver handle stock) on a glass slide and
watch what happens to the beam when you (a) open and close the
aperture iris (condenser) (b)open and close the field iris;
(c) create oblique illumination (d) create darkfield
illumination. Then there are a whole series of discussion you can
get into relating to numerical aperture, resolution, etc.
I hope that these are helpful. "Playing with Light" has always been
a joy for me. I hope you are able to share that with the people in
your program.
Good hunting!
Barbara Foster, President & Chief Consultant
Microscopy/Microscopy Education*
7101 Royal Glen Trail, Suite A - McKinney, TX 75070 - P: 972-924-5310
www.MicroscopyEducation.com
"Education, not Training"
MME is currently scheduling courses for now and through the end of
2015. We can customize a course on nearly any topic, from
fluorescence to confocal to image analysis to SEM/TEM. Call us today
for a free training evaluation.
*A subsidiary of The Microscopy & Imaging Place, Inc.
At 07:16 PM 4/2/2015, Jorge Toledo wrote:
>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>Post images on http://www.imgur.com and include the link in your posting.
>*****
>
>Dear
>Thanks to the information submitted by you a few months ago we in Chile
>(Latin America), we organized a series of activities around "light year".
>For this the most important organization of scientific education in our
>country has undertaken several activities around this topic. (
>http://www.explora.cl/conocer-ilumina)
>
>The reason for this email is to ask your help in one of these activities,
>We need different educational experiments related to the light, that can be
>performed at home or in schools with affordable materials.
>
>Any ideas will be very grateful
>from already thank you very much
>best regards
>Jorge
>
>
>--
>Jorge Toledo H
>PhD(c)
>Microscope Facility Manager
>Facility for Advanced Imaging and Microscopy (FAIM)
>Faculty of Medicine
>University of Chile
>www.faim.cl | www.scian.cl
>
>
>
>--
>Jorge Toledo H
>PhD(c)
>Microscope Facility Manager
>Facility for Advanced Imaging and Microscopy (FAIM)
>Faculty of Medicine
>University of Chile
>www.faim.cl | www.scian.cl
|
