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: 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


    User Avatar
    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


    User Avatar
    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 !
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook