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Homework Help: Wave question

  1. Sep 18, 2007 #1
    1. The problem statement, all variables and given/known data
    set t=pi/50 and find the points where the wave interferes constructively and destructively

    3. The attempt at a solution

    So I tried to take the derivative of y1 and y2 added together and set it equal to zero.

    [tex] 120*sin(\frac{2 \pi}{5}-30x) = 120*sin(\frac{2 \pi}{5}+30x)[/tex]

    then I took out the 120 on both sides, but I am not sure what to do from their exactly. I tried to take the arcsin a few different ways but I couldn't get anything concrete.

    I know the answer is [tex] x= \frac{\pi}{60}+\frac{2 \pi n}{30} [/tex] for constructive
    and [tex] x= \frac{n \pi}{30} [/tex] for destructive

    this makes sense to me since the period would be 2pi/30 but I don't get how they actually got there. Could someone point me in the right direction
  2. jcsd
  3. Sep 19, 2007 #2
    Since both of these waves have the same amplitude and the same angular frequency when they interfere they will give 0 for destructive interference and wave*2 for constructive.

    wave1 + wave2 = 0 happens when?

    how does the constructive go?

    think about what a phase really means
    Last edited: Sep 19, 2007
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