After attending CU Teach Engineering's PD over the summer, I was psyched to participate in another training with this group. On Thursday, a small group of us met and built two different apparati to possibly use in class. First, we each received a lens to use with a smart phone or tablet in order to use the device as a microscope. We just taped these on for the afternoon, but you could set up a small contraption with a variable stage--similar to the one pictured here (check out
Instructables for basic instructions).
We had fun exploring textures around the room and checking out skin cells!
The other apparatus that we built was a lego colorimeter (check out the
ACS article for specific instructions).
You can saw off the tops of legos to create perfectly-fit cuvette
holders, use two small blocks with holes as LED holders, and then use
the bricks to create a dark box for measuring light
absorption/transmission . Two cuvettes are used to provide a longer
path length for the device. Then, LEDs are used as both a light source
(hooked up in series with a battery and a small resistor (35-65 ohms). A
second LED is set up on the other side of the cuvettes to serve as a
light sensor (did you know they could act as a light sensor? This was
news to me!), attached to a multimeter to measure voltage. While this
was intended as an engineering activity for chemistry, I can see this as
a fantastic activity for physics as well--it takes away the "black box"
nature of many devices (specs, etc) and shows students how light and
and electricity can be used to create tools for measuring a variety of
things. This is a nice step toward understanding how waves are used in
many medical devices. Also, because different colored LEDs can be
used, it provides a nice discussion for light and color
absorption/transmission.
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| Side View: Left side shows the leads for the light-detecting LED--these connect to a basic multimeter or voltmeter. | |
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| Note butt-end/base of LED stuck in hole of a small/thin block with leads protruding outward--identical LED insertion on other side of apparatus. |
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| View of the LED light source--you can see the leads coming out of the LED, connected to a 65 ohm resistor and a small watch battery. |
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| LED light source illuminating sample. |
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| View of the LED light detector (note: there is no sample between light source and the light detector) |
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| View from above of cuvette holders, light source (on Right) and light detector (left). |
