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Thread: making a dual slit experiment

  1. #1 making a dual slit experiment 
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    First off... Happy New Years everyone!

    I decided I want to TRY to make the dual slit experiment at home. The way I see it, I am going to need 3 things; something to project some form of light, something with slits for the light to pass through and something for the light to display on.

    The problem is that I have limited knowledge on the subject. Kinda a big problem but I hope to overcome it. I'm hoping that in the process of trying to make this, I will learn a lot more about waves and quantum mechanics. So I hope that you guys will give me suggestions and help guide me. Please point out any flaw no matter how stupid it may be. Thanks.

    I first started thinking about what I can use to make the slits in and how big the slits would have to be. I quickly realized just how stupid that is because depending on the wavelength of the light I need a different sized slit. So I turned to first figuring out what kind of light to use.

    First, I looked at visible light. It has a wavelength of roughly 400nm-700nm, 0.0004mm-0.0007mm. I know the slit has to be narrower than the wavelength and there is no way I can make anything that small. Second, I looked at infrared and had a similar problem.

    So I decided to work backwards. I have 2 options; microwaves, about 1cm wavelength and radio waves, about 1m. I am a bit hesitant on microwaves because I don't think it's safe. I have therefore decided on using radio waves because it has a usable scale and I can very easily get a hold of a walkie talkie or something to generate them. I think I would also need a prism to diffract the wave so I only get one wavelength, as radio waves have a fairly large range in wave lengths.

    I am not sure about the dimensions of the slits. I know the slit has to be narrower than the wavelength. I assume that the distance between slits also has to be shorter than the wavelength, so that the wave can pass through both slits. I don't know how tall the slit should be, but I don't think it would matter, right? I'd appreciate any info on this part of the experiment.

    Radio waves do have some problems that light and infrared lack. First, they can penetrate many materials. I think I can get around this by using steel. But how thick would this steel need to be? The other problem I can think of is radio waves are not visible to our eyes, how should I go about detecting them?

    Hmm... this post came out to a lot longer than I expected ... Sorry about that! Any help would be appreciated.


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  3. #2  
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    Here are a couple of ways to do it

    http://www.altair.org/TwoSlit.html
    http://www.juliantrubin.com/bigten/youngdoubleslit.html


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  4. #3  
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    You can probably try and get a slit for light from your local secondary school.
    Also if you use light you will need a single slit to make it a monochromatic source.
    Microwaves are perfectly safe as long as you handle it correctly.
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  5. #4  
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    Thanks Harold, I'll give those a try. They seem pretty easy.
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  6. #5  
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    While you are at it, you might want to try single slit diffraction as well.
    http://chem.lapeer.org/PhysicsDocs/G...00/Laser2.html
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  7. #6  
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    Is it possible to change the frequency of laser light in realtime and if so, how would this affect the interference pattern?
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  8. #7  
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    You can't change a laser's color, but you could just substitute a different color laser. The website below has a java applet that shows the effect of changing the light color or slit spacing.
    http://www.walter-fendt.de/ph14e/doubleslit.htm
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  9. #8  
    Forum Freshman IrishStu's Avatar
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    Quote Originally Posted by Harold14370
    You can't change a laser's color, but you could just substitute a different color laser. The website below has a java applet that shows the effect of changing the light color or slit spacing.
    http://www.walter-fendt.de/ph14e/doubleslit.htm
    Cheers for that Harold!
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