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Homework Help: Phase difference between waves

  1. Mar 23, 2010 #1
    1. The problem statement, all variables and given/known data

    The diagram attached shows two coherent sources P and Q which produce waves of the same phase with wavelength , labda . If the two waves meet at the point R , the phase difference between waves at R is ??

    2. Relevant equations

    y=a sin (omega t + kx)

    3. The attempt at a solution

    i have problems obtaining the equation for wave p and q respectively , i know i have to find the superposition of the wave ?

    Attached Files:

  2. jcsd
  3. Mar 23, 2010 #2


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    Homework Helper

    Re: waves

    If P and Q are equidistant from R, then the phase difference between the waves at R is equal to zero.
  4. Mar 23, 2010 #3
    Re: waves

    but PR is not equal to QR , which part of the question says they are equal ?
  5. Mar 23, 2010 #4


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    Homework Helper

    Re: waves

    If PR = x1 and QR = x2, then
    y1 = a*sin(ωt + kx1)
    Y2 = a*sin(ωt + kx2)
    y1 + y2 = a*[sin(ωt+kx1) + sin(ωt+kx2)]
    = a*2*sin[ωt + k(x1+x2)/2]*cos[(x1-x2)/2]
    = 2*a*cos[(x1-x2)/2]*sin[ωt + k(x1+x2)/2]
    Now find the phase difference.
  6. Mar 24, 2010 #5
    Re: waves

    thanks !
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