Building Young's Double-Slit Interference Experiment?

TucsonTed asks: "I am a student teacher, preapring for life as a middle or high school teacher. I'd like to build a working model of Young's Double-Slit experiment to show light's wave behavior. Anyone have info on where I can find some blueprints (size of slits, spacing, etc.?) I don't yet have access to a real lab, so I need the DIY approach. I can use monochromatic light or a laser. If you haven't come across this experiment, and its freakish implications at the quantum level, take a look. You may not sleep tonight." For those interested in the math behind this experiment, you might want to check this site.

Comments

simple physics

[zoombah]

We performed this experiment last year in my sophomore physics class. All you really need is a laser (one of my classmates had one of those pointing devices), and a few plastic sheets. Arrange them according to the diagram given in any high-school physics textbook. You will see clear patters of wave interference on the screen. This is a crude form of the experiment, if you seek to conduct this in a more professional manner you can upgrade the materials accordingly.

I did this today

[nomis80]

This is some weird kind of coincidence! I just did this experiment in school today!

What we used was a laser and a small metal sheet which had two very tiny slits in it. I forget the spacing and the width of the slits, but I have it somewhere in my papers if you still want it. Since it was a simple sheet of metal, I suppose you'd be able to make those slits using an exacto. You don't need to be precise, as it will only create a different kind of pattern.

What is also easy to make is to team people in pairs and have them use the laser to determine who has the thickest hair. Don't tell them if the pattern has to be wider or thinner depending on the width of the hair, let them figure it out by themselves. We had some pretty weird theories going. ;)

A couple ideas...

[coyote-san]

A couple ideas....

1) Bolt two single-edge razor blades together, use them the draw parallel slits on smoked glass. It would probably not be wise to give middle-school students access to the blades... :-)

2) Bolt two single-edge razors blade-to-blade. One side can be fixed, the other adjusted by a screw. Instant variable size single slits, and you should be able to make this middle-school student safe.

3) Take out your trusty laser printer and print two vertical lines on a sheet of bright white paper. Photograph it with true B&W film (not that new "color process" junk), cut the film with your handly single-edge razor and install it in a 35mm slide holder.

4) Use the same technique to produce other fun patterns. E.g., besides single and double slits, gratings, etc., there's the starburst pattern where you alternate white and black wedges. Each wedge is 1/2 to 5 degrees wide. You *will* see weird printer artifacts, but you can minimize this by explicitly setting both black and white pixels. (Easy with postscript, I don't know about other tools.)