Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Double slit Problem

  1. Sep 23, 2008 #1
    Two lasers are shining on a double slit, with slit separation . Laser 1 has a wavelength of , whereas laser 2 has a wavelength of . The lasers produce separate interference patterns on a screen a distance 5.80 away from the slits.

    Part A
    Which laser has its first maximum closer to the central maximum?

    Part B
    What is the distance between the first maxima (on the same side of the central maximum) of the two patterns?
    Express your answer in meters.

    Part C
    What is the distance between the second maximum of laser 1 and the third minimum of laser 2, on the same side of the central maximum?
    Express your answer in meters.

    Not sure where to start .......

    currently working with wavelength = (Y*D)/(mR)
     
  2. jcsd
  3. Sep 25, 2008 #2
    Have you tried to use LaTeX or something there? You appear to be missing your wavelengths.
     
  4. Jan 30, 2011 #3
    if you are using the text book: "physics for scientists and engineers" second edition by KNIGHT, you should check out page 675 there are two formulas that is help for. I will list them below in case you are using another texbook.
    First one: y_m(y subscrip m) = [m*(lambda)*L]/d where m can be interger.-> position of bright fringes (maximum
    second one: y'_m(y' sbscrop m) = [(m+1/2)*(lambda)*L]/d where m can be interger.-> position of dark fringes (minimum)

    To help you approach the question, you should compare the change in y by formula one list above. where for laser one, lambda = d/20 ,and laser two, lambda = d/15.
    just plug the number in and calculate, the one with lower is closer to central maximum.
    (use 1 for m for both, since 0 is central maximum)

    part B: use the calculation above to help you solve this one out, subtract both.(watch the signs, keep it positive)

    Part C: similar like Part A calculation, where you should be careful with the "m" you use.
    For maximum count from 1 because 0 is central max, thus second maximum of l aser 1 use m=2. For minimum count from 0, since there is actully no central min. so the third minimum of laser 2 is still m=2. and then just plug in the number and calculate. keep the result positive.

    If you have any further question just take a look of the text book, or you can post it and i will tried to answer.

    If there is anything incorrect people find from my message please that me know..thanks
     
  5. Jan 30, 2011 #4
    i think it's the question from mastering physics..but i could be wrong.. the wavelengths for laser 1 is d/20 and laser 2 is d/15..
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook