hi i am a mom with a kid whos into physics
just wanted to say im doing the double slit experiment just now, planning to use a mirror to concentrate the light then put it through a red gel filter then through a small hole then through the slits into the wall hoping that is all i will need to do. having huge trouble getting the slits parallell and close enough togehter. anyone have any tricks for slicing the foil? that would be great. also not sure a red gel will actually filter to red, some blue gels filter to red weirdly so will have to try a few, will it work with only white light or will i end up with a rainbow? i suppose we will find out. if i dont get through this entire roll of foil before i get a slit pair!
In the old days, when I was at school, we used a glass slide, coated with soot from a candle flame ('lamp black'). I seem to remember using two needles, pushed through a cork - sloping slightly towards each other and dragged across the black surface using a ruler. It's a better natured medium than foil, which distorts as you cut it and the slits were good enough to produce good fringes. (We didn't have kitchen foil and our source would have had to be second hand chocolate wrappers - which would actually be a lot thinner an better behaved than Baco Foil. A laser pointer would be pretty cheap and a better source than a filtered lamp.
It's worth googling "Young's slits home experiment" to get plenty of other ideas. Using two human hairs and spray paint on the glass could work well.
With a laser pointer and a human hair you get a clear diffraction pattern, without anything else required.
Of course, this is not double slit. But using a laser pointer is a good idea, at least as a first step. It will be so much easier than using "natural" light.
This video shows a very simple way to do it at home using a laser pointer and a DVD disk. The "slits" in the disk are only 700 nanometers apart.
A laser pointer, or a red LED light, is a much easier way to get monochromatic light than using a filter.
The pattern from a grating is not the same as the pattern for two slits, though. It's a good experiment to do but you are dealing with a cheap and cheerful Diffraction Grating (many sources), rather than the (two) slits.
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