Wednesday, February 4, 2015

Homemade Microscope

My husband recently cashed in some credit card rewards and got my sons a microscope. Before they really got into using it, I thought it would be fun to make our own so they could begin to understand how it works.

Our simple recreation teaches the principles of light reflection, surface tension, and magnification. And it uses simple household objects you're likely to find in your recycle bin.

Empty wide-mouthed glass jar with a smooth bottom
Lid for the jar
Clear hard plastic from food packaging
Aluminum foil
Chipboard (think empty cereal box)
Fine-grain salt
Toothpick or medicine dropper

How to Make It
1. Poke a hole in the middle of the jar lid. We hammered a nail through ours with a cutting board underneath. You'll want your hole to be big enough to see through (think half the size of a paper punch hole). Ours was a little small.

2. Cut a small rectangular piece of plastic from food packaging (we used a plastic strawberry container).

3. Tape it over the hole in your lid. Set aside.

4. Cut a strip (say 1 1/2-inch wide) out of chipboard. Glue the aluminum foil to the cardboard shiny side up. You'll want to fold the strip at 1/3rd its length so it fits inside the upside down jar; cut, if necessary. It will look like short ramp.

5. Put the foil ramp on top of your sheet of paper and put the upside down jar on top of it.

6. Turn the paper to shift the foil ramp so that when you're looking down through the jar light is reflected up into your eye.

7. Put a few granules of salt onto the bottom of the jar. Make sure they are dispersed and not clumped together.

8. Now using the medicine dropper or toothpick dipped in water, add a droplet to the lid, on top of the clear plastic directly over the hole. If you're using the toothpick to pick up and dispense water, you'll have to build this droplet.

9. Now hold the lid over the salt and peer through the droplet hole. You'll be able to see how the flecks of salt suddenly look like geometric shapes. You can move the lid closer or farther away from the salt to see if that increases the magnification.

This great idea came from Mr. Wizard, who I remember fondly from my childhood. This video clip walks you through all the steps and an explanation of the science behind why this works.

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