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Homework Help: Wave constructive and/or destructive interference question

  1. Oct 16, 2014 #1
    1. The problem statement, all variables and given/known data

    The figure shows two sets of water waves, created by two sources labeled "A" and "B." The solid half-circles represent wave crests from A, and the dashed half-circles represent wave crests from B. Suppose that individual wave crests from either source A or source B alone are 5 mm above the level of the undisturbed water. Then the displacement of the water [above or below the level of the undisturbed water] at the point marked "x" [with the arrow pointing toward it] is

    A.) -10 mm.
    B.) 0 mm.
    C.) +5 mm.
    D.) +10 mm.
    E.) -5 mm.

    2. Relevant equations


    3. The attempt at a solution
    I think it would be E.) -5mm because if we are just taking one wave set alone (either A or B) then there would be no interference from the other wave set and if the displacement from rest is 5mm then the opposite displacement must be equal in magnitude...? But I don't actually know...I'm just thinking it out....would you please correct me if I'm wrong? Thanks in advance!
  2. jcsd
  3. Oct 16, 2014 #2


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    Homework Helper

    I cannot see your figure. Could you check to see that it was attached properly?
  4. Oct 16, 2014 #3


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    Although I cannot see the picture, here is a hint. You can add the wave effects together. So, if x lies on a wave crest from A, (+5mm), and the midpoint between crests from B (-5mm), then the total displacement at x would be 0.
  5. Oct 20, 2014 #4

    Yes, unfortunately there was no way to upload the image but thank you for your help...it actually helped me get the answer! :)
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