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: Two loudspeakers, finding amplitude.

  1. Nov 27, 2007 #1
    1. The problem statement, all variables and given/known data
    Two in-phase loudspeakers emit identical 1000 Hz sound waves along the x-axis. What distance should one speaker be placed behind the other for the sound to have an amplitude 1.60 times that of each speaker alone?

    2. Relevant equations
    None given, but I assume:
    A = 2asin(kx)

    3. The attempt at a solution

    1.6a = 2asin(kx)

    Found k=(2pi)/wavelength = (2pi/0.343)
    using v = 343 m/s


    x = 0.0506m

    But this answer is wrong. Help?
    Last edited: Nov 27, 2007
  2. jcsd
  3. Nov 27, 2007 #2


    User Avatar
    Homework Helper

    You have to add the amplitudes as vectors.
    (1.6*a)^2 = a^2 + a^2 + 2*a*a*cos(phi) where phi is the phase difference = 2*pi*x/wavelength
  4. Nov 27, 2007 #3
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook