1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Interference pattern problem

  1. Mar 4, 2006 #1
    Anyone can help me on this one.

    A plane wave of wavelength [tex]\lambda[/tex]= 550 nm is incident normally on an opaque screen with three narrow parallel slits separated by distance a= 2.3 mm. An interference pattern is observed on the other side of the screen at a large distance from it.
    (a)At what angles are the first principal maxima adjacent to the central maximum?
    (b)How does intensity, Imax, at the principal maxima compare to that from a single slit, I1?

    in (a) can I use asin[tex]\theta[/tex]=m[tex]\lambda[/tex] to get the angle?
  2. jcsd
  3. Mar 4, 2006 #2
    from my notes (as im studying this aswell) i believe your answer from (b) should lie.... or could possibly be I= N^2 * Io

    for a i would use asin[tex]\theta[/tex]=m[tex]\lambda[/tex] aswell but im not so sure on this one, optics isn't exactly my best subject at the moment
  4. Mar 5, 2006 #3
    For a maximum, the amplitudes will add in phase when a.sin(theta) = lambda, if a is the slit-to-slit spacing. For a minimum, you have to figure out when 3 waves will add to zero. The intensity is proportional to the square of the sum of the amplitudes.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook