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Single slit double slit and diffraction grating

  1. Dec 11, 2013 #1
    1. The problem statement, all variables and given/known data
    1. From conservation of energy point of view if single and double slits, and diffraction grating had slits of same width, how should their overall light intestines compare
    2. under what conditions can we consider double-slits intensities as approximately constant?
    3.Describe the similarities and difference between double slit and diffraction grating patterns? explains reasons for them, (i can get the similarities and difference but i cant explain them)


    2. Relevant equations
    none

    3. The attempt at a solution
    5.
    The similarities between double slit and diffraction grating pattern are that they both have the same location for their bright and dark bands, as well as they have the same distance in between dark and bright bands. The differences are that grating pattern has more intense bright bands, and the bright bands are narrower and more sharply peaked. While the double slit have bright bands with less intensity and wider peaks at the bright bands. This is because for diffraction grating at angles between maxima, the waves from each slit differ in phase, and interfere to produce relatively wide dark areas on the screen; the overall result is a pattern of extremely narrow maxima.

    6.
    The light intensities of the double-slit bands did not stay constant, instead one saw as the wave diffracted further away from the center, the light intensities decreased, this is because in real life the width of the slits causes each slit to act like a single slit, and the non uniform single-slit pattern combines with the ideal double-slit pattern, therefore dimming occurs as it moves away from the center. The double-slit intensities will stay constant if the width of the slits is very small.

    7.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 11, 2013 #2

    Simon Bridge

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    Welcome to PF;
    All that is very good so far - but did you have a question?

    What happened to "4." ?
    Have you attempted 1. 2. and 3. yet?
     
  4. Dec 11, 2013 #3
    Yea srry i made it very unclear as i copied and pasted my answer from my lab
    The answer to 2 is 5 and answer
    To 3 is 6 and i cant seem to get an answer for 1 but i think that since theyre all same width double slit will have double the light go through so double the photons so double the energy so more energy is conserved
     
  5. Dec 12, 2013 #4

    Simon Bridge

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    You are right about 1. but it asks for a "conservation of energy" POV.

    5 does not answer 2, it seems to answer 3.
    also 6 looks like the answer to 2.

    I think you have the idea - it's just some details that need mopping up to get all the marks.
    For 3 you need to look at how the pattern gets formed... you do kinda explain it though.
     
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