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Thread: I am so lost with "nodal points",wavelengths HELP!

  1. #1 I am so lost with "nodal points",wavelengths HELP! 
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    My teacher goes through this physics work so quick, we're into the 2nd day of "The nature of the wavelength and Im completely lost.
    Nobody understands it, and neither do I!

    The things I do not understand:
    What are nodal points? Is this where the trough and crest meet? When they say that 2 nodal points are say, 6cm apart, does that mean they are completely beside eachother, or can they be anywhere?

    What is S1,S2, etc.? Is this where the light comes OUT of? Or is this the BEAMS of light? Are these the "slits" the light comes out of? So therefore there could also be an S3.S4 etc meaning more slits??

    What is "Xn"? What is this? A length or a point??... What does it connect?

    When it says "nodal lines" are these the lines that usually appear "blurry"? Meaning there is a destructive interference??

    Lambda is the wavelength, I know this.

    Delta d is the distance between S1, and S2, right?

    What is the "screen"??

    What is L?

    When we're trying to find Beda/or Theta, where is that angle? I know that you are supposed to create a new angle because the orginal angle is too small, but i have NO idea where that is, or how you create the new, more clearer angle?

    PLEASE HELP!
    Sorry if there are so many questions, I just want to understand thoroughly.
    Please use pictures if you can! If not, any help is already greatly appreciated!
    Please do not use the terms I already don't know to describe other terms I dont know
    Thank you so much! :-D


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  3. #2  
    Forum Ph.D. Leszek Luchowski's Avatar
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    Hello;

    I would love to help, and I am sure many others would, but most of your questions lack context. "What is S1 and S2", for example, can only be answered by someone who has (or at least has seen) the same textbook as you have.

    Please calm down and try to rewrite your questions in a way that more people can understand.

    Looking forward, Leszek.


    Leszek. Pronounced [LEH-sheck]. The wondering Slav.
    History teaches us that we don't learn from history.
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  4. #3  
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    Oops! Sorry...
    I thought it was just like, universal...Like I said I have no concept of this stuff, so
    I just thought it was considered like "lamba" or something!

    I really wish I had a picture to explain....
    There are 2 points they are usually named S1 and S2. Im unsure as to what they are, that's why i was asking, but i dont have a diagram to help me out....

    The concept is that a light, with a constant frequency, and wavelength ends up splitting into 2, as you put a "slide" that has 2 slits ontop of it. It ends up creating a bunch of little dots that are of equal distant apart when they hit a surface.
    Does that help at all?
    Sorry i dont really grasp all of the concepts yet, so Im not sure if i make total sense. haha
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  5. #4  
    Moderator Moderator Dishmaster's Avatar
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    Ah, it sounds like a diffraction pattern of monochromatic light caused by a double slit experiment. This pattern is caused by constructive interference. This means that maxima of the emitted light wave meet at the screen after they have passed the double slit. Such interference can only happen at points, where the path lengths between the light source and the screen are identical or only differ by an integer number of wavelengths. Destructive interference (dark ranges on the screen) are produced, when maxima and minima of the light wave meet. You might try to draw a simple graph and verify this fact. Here are a few websites that might help:
    http://www.colorado.edu/physics/2000...two-slit2.html
    http://theory.uwinnipeg.ca/physics/light/node9.html
    http://farside.ph.utexas.edu/teachin...s/node151.html
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  6. #5  
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    Take a look at this Wikipedia article on standing waves to help you understand the concept of a node.
    http://en.wikipedia.org/wiki/Standing_wave
    It seems you are studying the double slit experiment. Here is a web site that might help.
    http://hyperphysics.phy-astr.gsu.edu...opt/slits.html
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  7. #6  
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    wow, thanks guys!!
    I have a stronger grasp on this now
    Thank you!
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