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

  1. Oct 19, 2011 #1
    1. The problem statement, all variables and given/known data
    Sources A and B emit long-range radio waves of wavelength 550 m, with the phase of the emission from A ahead of that from source B by 90°. The distance rA from A to a detector is greater than the corresponding distance rB from B by 140 m. What is the magnitude of the phase difference at the detector?

    2. Relevant equations

    3. The attempt at a solution

    Initially, source A leads source B by 90°, which is equivalent to \frac{1}{4} wavelength.
    However, source A also lags behind source B since rA is longer than rB by 140 m, which is \frac{140}{550}=0.2545 wavelength. So the net phase difference between A and B at the
    detector is -0.732 Rad.

    This is wrong though, can someone help me =D
    Last edited: Oct 19, 2011
  2. jcsd
  3. Oct 19, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    How'd you come up with -0.732 rad? It looks like you completely ignored one of the terms.
  4. Oct 19, 2011 #3
    To be honest I'm not sure.
    I have tried everything I can think off but all my answers are wrong.
  5. Oct 19, 2011 #4
    Thank you for your time but I asked a friend and he showed me. It was just a stupid mistake that I missed thank yiu
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook